Uroptychus, Henderson, 1888

Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), Tropical Deep-Sea Benthos (Mémoires du Muséum national d'Histoire naturelle 212), pp. 1-612 : 19-37

Genus UROPTYCHUS Henderson, 1888

Diptychus A. Milne Edwards, 1880:63.

Uroptychus Henderson, 1888: 173 [replacement name for Diptychus (junior homonym of Diptychus Steindachner, 1866 , Pisces)]. — Alcock 1901: 281. — Baba 1988: 17; 2005: 26, 216. — Baba et al. 2009: 32. — Macpherson & Baba 2011: 49.

DIAGNOSIS„ Carapace dorsally smooth, granulose, with scaly ridges or spines, lateral margin smooth or spinose, anterolateral spine distinct, rarely obsolete. Rostrum narrowly or broadly triangular, flattish, laterally smooth or with small spines. Lateral limit of orbit acuminate, rounded or with small spine. Pterygostomian flap proportionately high from anterior to posterior, rarely very low on posterior half. Anterior margin of sternal plastron distinctly concave, with or without submedian spines and median notch or sinus. Excavated sternum anteriorly ending between bases of Mxp1, with or without median spine or ridge. Antennal scale articulated with or fused to article 2, flagellum of no great length, directed anteriorly, never overreaching tip of P1. Left and right Mxps3 broadly separated from each other, with distal parts accommodated in excavated sternum when folded. P1 spinose or unarmed, ischium with distodorsal spine. P2-4 dactyli with flexor marginal spines of various sizes and arrangements, P4 carpus subequal to, somewhat shorter than, or rarely longer than P3 carpus.

REMARKS„ With the description of 100 new species in this paper, the Indo-West and Central Pacific species of the genus are now 219 in number, 125 of which are recorded for the first time from New Caledonia and vicinity, the major region surveyed by the French cruises (see Materials and Methods). Prior to this study, only one species, Uroptychus amabilis Baba, 1977 , which occurs in shallow water, was known from New Caledonia.

Chirostylus ciliatus Van Dam, 1933 and Gastroptychus spinirostris Ahyong & Poore, 2004 have been transferred to Uroptychus ( Baba 2005) . These two species are grouped together with U. chacei ( Baba, 1986b) and three new species described in this paper, all characterized by the spinose body and appendages, especially maxilliped 3 bearing a strong distomesial spine on the ischium, a feature not observed in other species of Uroptychus . These species would better be placed in a different genus, as suggested by molecular data that showed that U. spinirostris is placed in a different clade than other species of Uroptychus ( Bracken-Grissom et al. 2013) . However, they remain in Uroptychus , pending extensive studies.

Uroptychus scambus Benedict, 1902 is now placed in the new genus Heteroptychus , together with eight other species including six new species and one western Atlantic species (see below under Heteroptychus ).

Uroptychus also contains the following aberrant species or species groups, each of which may be shifted to a different genus, but they are retained in the genus until extensive studies have been done, reviewing other related species using molecular data. These include U. naso Van Dam, 1933 and two related species; U. scandens Benedict, 1902 and three related new species; U. ctenodes n. sp.; U. diaphorus n. sp.; and U. inaequalis n. sp., U. pilosus Baba, 1981 and U. plautus n. sp. Uroptychus naso Van Dam (1933) has recently been reviewed by Poore & Andreakis (2011), with descriptions of two related new species based upon morphological and molecular data. Apparently these species are unusual among the Uroptychus species in having very narrow dorsal orbital margin and elongate rostrum, with the mesial half of the eyes concealed beneath the rostrum. Uroptychus scandens Benedict, 1902 as defined earlier by having truncate dactyli of P2-4 proved to contain four species as suggested by molecular data (L. Corbari, pers. comm.). Uroptychus ctenodes n. sp. is also unique in the genus in having the carapace dorsal surface crested along the lateral margin, with a strong anterolateral spine directly lateral to the rounded lateral limit of the orbit, and the pterygostomian flap very low in the posterior half as in Heteroptychus n. gen. Uroptychus diaphorus n. sp. shows a different spination between P2 and P4 dactyli (P3 is missing in the sole specimen), the fact suggesting a possible shifting of the species to a different genus as has been applied to Uroptychodes Baba, 2004 (see Baba 2004). Uroptychus inaequalis n. sp., U. plautus n. sp. and U. pilosus Baba, 1981 are different from the other species of Uroptychus in having only two terminal spines instead of a row of flexor marginal spines.

There still remain problematic species because of their brief accounts: Uroptychus bacillimanus Alcock & Anderson, 1899 , U. cavirostris Alcock & Anderson, 1899 , U. fusimanus Alcock & Anderson, 1899 , U. indicus Alcock, 1901 , and U. nigricapillis Alcock, 1901 , all from the Investigator collection and now housed in the Zoological Survey of India, Calcutta. Examination of the types of these species is required to elaborate on their specific status, but for now the material is inaccessible. The relationships between U. cavirostris and U. latirostris Yokoya, 1933 still have not been settled. The western Indian Ocean material reported under U. cavirostris by Tirmizi (1964) is an undescribed species (see under the remarks of U. latirostris ). Uroptychus nigricapillis as appeared in the literature appears to represent a complex of species (see below under this species).

The following species are not included in the key to species from the Indo-West and Central Pacific, because of lack of sufficient morphological details to secure their identity: Uroptychus nitidus (A. Milne Edwards, 1880) from off East London ( Barnard 1950), off Durban ( Kensley 1977), Laccadive Sea [13°47’49”N, 73°7’E ( Anonymous 1914)] ( Alcock & Anderson 1894), Bay of Bengal [8°44’40”N, 81°20’15”E ( Anonymous 1914)] ( Anderson 1896). One female specimen of U. nitidus collected by the R/V Meiring Naude at Station 121 south of Durban in 900- 625 m and identified by B. Kensley, now in the collection of the Smithsonian Institution (USNM 1101919), was examined. It looks identical to the material reported by Kensley (1977) from off Durban but is clearly different from U. nitidus sensu stricto in having the P2-4 propodi with the terminal spine single, not paired as in the typical form of U. nitidus defined by Chace (1942) ( Baba & Wicksten 2017a). This is identical to the material reported under U. gracilimanus from Madagascar by Baba (1990), as well as the specimens reported under U. australis var. indicus from Zanzibar by Tirmizi (1964), the identification verified by examination of the material of both (see below under the remarks of U. psilus n. sp.). It is apparently an undescribed species and will be described later elsewhere. Actually, true Uroptychus nitidus is a western Atlantic element ( Baba & Wicksten 2017a), so the Investigator material ( Alcock & Anderson 1894; Anderson 1896) will in all probability prove to be a different species.

The taxonomic status of U. gracilimanus var. bidentatus Doflein & Balss, 1913 from off the east coast of the Somali Republic has not yet been fixed, pending examination of the syntype, ZMB 17483, now in the collection of the Zoologisches Museum, Zentralinstitut der Humboldt-Universität, Berlin.

Uroptychus inclinis Baba, 2005 from the Kai Islands is synonymized with U. tridentatus ( Henderson, 1885) in this paper.

KEY TO SPECIES FROM THE INDO- WEST AND CENTRAL PACIFIC

1. Dorsal margin of orbit extremely narrow; mesial half of cornea concealed beneath rostrum, not visible in dorsal view ............................................................................................................................................................................... 2

– Dorsal margin of orbit relatively broad; entire cornea visible in dorsal view ....................................................... 4

2. Sternal plastron 1.1-1.2 × longer than broad. P2 propodus lacking dense tufts of short setae on lateral and mesial faces .................................................................................................................................... U. naso Van Dam, 1933

– Sternal plastron at least 1.4 × as long as broad. P2 propodus with dense tufts of short setae in 2 rows on each of lateral and mesial faces ..................................................................................................................................................... 3

3. Rostrum with lateral spines on distal half. Posterior branchial margin with 6-7 strong spines widely spaced anteriorly, closely spaced posteriorly ............................................................ U. pinocchio Poore & Andreakis, 2011

– Rostrum with lateral spines on distal two-thirds. Posterior branchial margin with 9 strong spines evenly spaced by narrow U-shape ................................................................................... U. cyrano Poore & Andreakis, 2011

4. Rostrum very broad, basal breadth at least two-thirds carapace breadth measured at posterior carapace margin........................................................................................................................................................................................ 5

– Rostrum basal breadth usually half or less than half, rarely slightly more than half carapace breadth measured at posterior carapace margin ..................................................................................................................................... 10

5. Anterior margin of sternite 3 with pair of submedian spines .................................................................................. 6

– Anterior margin of sternite 3 without pair of submedian spines (obsolescent spines may be present) ......... 8

6. Rostrum distally narrowed, lateral margin somewhat concave. Epigastric region with tubercles behind each eye. Posterior plate of telson laterally and posteriorly convex, not semicircular ........ U. mauritius Baba, 2005

– Rostrum equilateral broad triangular, lateral margin straight. Epigastric region smooth. Posterior plate of telson semicircular ................................................................................................................................................................. 7

7. Rostrum half as long as broad, not reaching end of cornea ........................................... U. simiae Kensley, 1977

– Rostrum about as long as broad, overreaching cornea .................................. U. alcocki Ahyong & Poore, 2004

8. P1 merus proximally strongly narrowed, distally less so, shaped like a bowling pin. Posterior plate of telson long trianguloid, ending in rounded margin ...................................................... U. yokoyai Ahyong & Poore, 2004

– P1 merus not narrowed distally. Posterior plate of telson subsemicircular or with emarginate posterior margin [Differences in the following couplet are so slight that examination of the type material of U. cavirostris is recommended] ....................................................................................................................................................................... 9

9. Sternite 3 without distinct submedian spines on anterior margin. Telson distinctly emarginate on posterior margin ............................................................................................................... U. cavirostris Alcock & Anderson, 1899

– Sternite 3 with obsolescent submedian spines on anterior margin. Telson slightly or barely emarginate on posterior margin ..................................................................................................................... U. latirostris Yokoya, 1933

10. P2-4 dactyli truncate ..................................................................................................................................................... 11

– P2-4 dactyli distally narrowed ........................................................................................................................................ 14

11. Antennal scale fused with article 2 ............................................................................................................................ 12

– Antennal scale articulated ............................................................................................................................................... 13

12. Eyes distally narrowed (cornea narrower than remaining eyestalk) ................... U. scandens Benedict, 1902

– Eyes subequally broad proximally and distally (cornea as broad as remaining eyestalk) ....... U. parisus n. sp.

13. Eyes distally narrowed (cornea narrower than remaining eyestalk) ................................. U. articulatus n. sp.

– Eyes subequally broad proximally and distally (cornea slightly broader than remaining eyestalk) ................... ..................................................................................................................................................................... U. imparilis n. sp.

14. Carapace dorsal surface crested laterally, anterolateral spine strong, reaching apex of rostrum. Pterygostomian flap with comb-like row of spines .............................................................................................. U. ctenodes n. sp.

– Carapace dorsal surface not crested laterally, anterolateral spine far falling short of apex of rostrum. Pterygostomian flap without comb-like row of spines ...................................................................................................... 15

15. P2-4 dactyli with 2 terminal (ultimate and antepenultimate) spines only ........................................................ 16

– P2-4 dactyli with flexor marginal spines (arranged in regular row or separated into distal and proximal groups) .................................................................................................................................................................................... 18

16. P2-4 dactyli with ultimate spine subequal to antepenultimate spine ............................ U. pilosus Baba, 1981

– P2-4 dactyli with ultimate spine more slender than antepenultimate spine ....................................................... 17

17. Anterolateral corner of carapace rounded, without anterolateral spine. P2-4 dactyli longer than carpi ...... .................................................................................................................................................................... U. inaequalis n. sp.

– Anterolateral corner of carapace angular, produced to small spine. P2-4 dactyli shorter than carpi. .............. ........................................................................................................................................................................ U. plautus n. sp.

18. Spines present on dorsal surface of cardiac and/or branchial region ................................................................ 19

– No spine on dorsal surface of cardiac and branchial regions ................................................................................. 33

19. P2-4 dactyli with penultimate spine prominent, much greater than (usually>2 ×, rarely>1.5 ×) antepenultimate ...................................................................................................................................................................................... 20

- P2-4 dactyli with penultimate spine subequal to or slightly larger than antepenultimate ............................... 25

20. Abdomen with spines on somites 1 and 2 ............................................................................ U. abdominalis n. sp.

– Abdomen unarmed .......................................................................................................................................................... 21

21. Dorsal spines of carapace strong, especially those on epigastric and anterior cardiac regions ....................... ................................................................................................................................................................ U. anoploetron n. sp.

– Dorsal spines of carapace small ..................................................................................................................................... 22

22. Posteriormost of carapace lateral spines largest ............................................................. U. paku Schnabel, 2009

– Posteriormost of carapace lateral spines distinctly smaller than preceding spine ............................................. 23

23. P2-4 propodi with no flexor marginal spine [it is most likely that a terminal pair of spines may have been overlooked] ............................................................................................................................. U. sexspinosus Balss, 1913a

– P2-4 propodi with row of flexor marginal spines, terminal paired ....................................................................... 24

24. Carapace with 3 spines on epigastric region, median one followed behind by 2 spines (1 on posterior gastric, 1 on cardiac region). Antennal article 5 with strong distomesial spine, antennal scale terminating in distal end of article 5 excluding terminal spine. P2-4 dactyli with 7-9 flexor marginal spines ........ U. angustus n. sp.

– Carapace with numerous small spines on entire dorsal surface. Antennal article 5 unarmed, antennal scale overreaching article 5. P2-4 dactyli with 21 flexor marginal spines ............................................................................. ......................................................................................................................... U. tracey Ahyong, Schnabel & Baba, 2015

25. Abdomen unarmed ........................................................................................................................................................ 26

– Abdomen with spine(s) at least on somite 1 .............................................................................................................. 28

26. P2-4 meri and carpi spinous [characters confirmed by examination of the syntypes, 2 males, 2 ovigerous females, BMNH 1966.2.3.23-26] ..................................................................................... U. spinimanus Tirmizi, 1964

– P2-4 meri and carpi without row of spines on dorsal or extensor crest .............................................................. 27

27. Carapace and P1 very spinous. P2-4 propodi with single terminal spine only on flexor margin [original description; but it may be a pair of spines] .............................................. U. fusimanus Alcock & Anderson, 1899

– Carapace and P1 with sparse spines. P2-4 propodi with pair of terminal spines preceded by row of single spines on flexor margin .............................................................................................................................. U. setifer n. sp.

28. Anterior margin of sternite 3 without median notch and submedian spines .......... U. chacei ( Baba, 1986b)

– Anterior margin of sternite 3 with median notch flanked by spine ..................................................................... 29

29. Rostrum proportionately broad distally, with 9 lateral spines ............................................ U. numerosus n. sp.

– Rostrum triangularly narrowed distally, with 1-5 lateral spines ............................................................................ 30

30. Rostrum much more than half (0.7-0.8) as long as carapace ........... U. spinirostris ( Ahyong & Poore, 2004)

– Rostrum at most half as long as carapace ................................................................................................................... 31

31. Sternal plastron broadest on sternite 4, subequally broad between sternites 5 and 7 ... U. quartanus n. sp.

– Sternal plastron successively broader posteriorly ...................................................................................................... 32

32. Small spines on abdomen, somite 3 with a few small spines. P2-4 dactyli with ultimate spine subequal to or slightly larger than penultimate spine ........................................................................ U. ciliatus ( Van Dam, 1933)

– Pronounced spines on abdomen, somite 3 with 2 transverse rows of strong spines. P2-4 dactyli with ulti- mate spine more slender than penultimate spine.............................................................................. U. senarius n. sp.

33. P2 dactylus with flexor marginal spines separated into proximal and distal groups by considerable dis- tance ........................................................................................................................................................................................ 34

– P2 dactylus with flexor marginal spines equidistant from one another or somewhat broadly interspaced distally, not remotely separated into proximal and distal groups ............................................................................. 40

34. Pair of strong epigastric spines ................................................................................................................................... 35

– No epigastric spines ......................................................................................................................................................... 37

35. P2-4 propodi with concave prehensile edge along distal part of flexor margin, distalmost of flexor marginal spines situated near juncture with dactylus, remarkably remote from distal second. Sternite 4 with strong lateral process [characters confirmed by examination of the syntypes, 1 male, 1 ovigerous female, BMNH 1966.2.3.21-22] ............................................................................................................... U. sternospinosus Tirmizi, 1964

– P2-4 propodi with straight prehensile edge along distal part of flexor margin, flexor marginal spines equidis- tantly arranged in regular row. Sternite 4 without strong lateral process ............................................................... 36

36. Antennal scale articulated with article 2 ................................................................ U. jiaolongae Dong & Li, 2015

– Antennal scale fused with article 2 ................................................................................................... U. adnatus n. sp.

37. P2-4 propodi with concave prehensile edge (distal part of flexor margin), distal-most of flexor marginal spines located near juncture with dactylus .................................................................................................................... 38

– P2-4 propodi with straight prehensile edge (distal part of flexor margin), distal-most of flexor marginal spines remote from juncture with dactylus ................................................................................................................... 39

38. Epigastric region without elevated ridges. P2 carpus as long as P2 propodus. P1 merus with 1 median spine on distodorsal margin ............................................................................ U. thermalis Baba & de Saint Laurent, 1992

– Epigastric region with pair of elevated ridges behind eyes. P2 carpus 0.8 × as long as P2 propodus. P1 merus unarmed on distodorsal margin ........................................................................... U. albus McCallum & Poore, 2013

39. P2-4 propodi with distalmost flexor marginal spine much more remote from juncture with dactyli than from distal second spine. Sternite 4 having anterolateral margin as long as posterolateral margin .................... ............................................................................................................................. U. remotispinatus Baba & Tirmizi, 1979

– P2-4 propodi with distalmost flexor marginal spine more remote from distal second spine than from junc- ture with dactyli. Sternite 4 having anterolateral margin much longer than posterolateral margin .................... ........................................................................................................................................................ U. vandamae Baba, 1988

40. P2 and P4 dactyli different in spination (P2 dactylus with small, loosely arranged spines oriented parallel to flexor margin on P2, P4 dactylus with closely arranged, obliquely directed spines) [P3 not known] ............. ................................................................................................................................................................... U. diaphorus n. sp.

– P2-4 dactyli with similar spination (flexor marginal spines obliquely or perpendicularly directed, or oriented parallel to margin) ................................................................................................................................................................ 41

41. P2-4 dactyli with spines oriented parallel to flexor margin (spines may be very small so as to be hardly identified as “oriented parallel”) ........................................................................................................................................ 42

– P2-4 dactyli with obliquely or perpendicularly directed spines ............................................................................. 50

42. P2-4 propodi with distalmost of flexor marginal spines remote from juncture with dactyli ....................... 43

– P2-4 propodi with distalmost of flexor marginal spines close to juncture with dactyli .................................... 44

43. Anterolateral margin of sternite 4 as long as or slightly shorter than posterolateral margin .......................... ......................................................................................................................................................... U. bispinatus Baba, 1988

– Anterolateral margin of sternite 4 much longer (>1.5 ×) than posterolateral margin ........... U. marcosi n. sp.

44. Distalmost of flexor marginal spines of P2-4 propodi single, not paired .......................................................... 45

– Distalmost of flexor marginal spines of P2-4 propodi paired ................................................................................. 46

45. Carapace as long as broad; anterolateral spine strong, overreaching lateral orbital spine. No spine on epi- gastric region .................................................................................................................... U. brevisquamatus Baba, 1988

– Carapace longer than broad; anterolateral spine small, not overreaching lateral orbital spine. Pair of spines on epigastric region ........................................................................................................ U. singularis Baba & Lin, 2008

46. Branchial margins subparallel. P1 ischium with subterminal spine on ventromesial margin ......................... ...................................................................................................................................................... U. webberi Schnabel, 2009

– Branchial margins convex. P1 ischium without distinct subterminal spine on ventromesial margin .......... 47

47. Lateral limit of orbit unarmed. Antennal scale proportionately broad distally, ending in blunt or rounded tip ........................................................................................................................................................ U. disangulatus n. sp.

– Lateral limit of orbit with small distinct spine. Antennal scale distally tapering ............................................... 48

48. Anterolateral spine of carapace situated directly lateral to lateral orbital spine .................................................. ............................................................................................................................................... U. brevirostris Van Dam, 1933

– Anterolateral spine of carapace situated posterior to position of lateral orbital spine ..................................... 49

49. Branchial margin ridged along entire length. Antennal article 2 with very small distolateral spine .............. ............................................................................................................................................................ U. setosipes Baba, 1981

– Branchial margin ridged along posterior third of length. Antennal article 2 with distinct distolateral spine ............................................................................................................................................. U. australis ( Henderson, 1885)

50. P2-4 dactyli with penultimate spine much broader than (usually>2 ×, rarely>1.5 ×) antepenultimate .. 51

– P2-4 dactyli with penultimate spine subequal to or somewhat broader than antepenultimate ................... 104

51. Antennal article 5 broadened distally, much broader than antennal scale ................ U. buantennatus n. sp.

– Antennal article 5 not broadened distally, narrower than antennal scale ........................................................... 52

52. Anterolateral spine of carapace smaller than or subequal to lateral orbital spine .......................................... 53

– Anterolateral spine of carapace distinctly larger than lateral orbital spine ......................................................... 63

53. Flexor marginal spines of P2-4 dactyli perpendicularly directed (proximal small spines may be oblique) .. ................................................................................................................................................................................................... 54

– Flexor marginal spines of P2-4 dactyli obliquely directed ....................................................................................... 58

54. Abdominal somite 2 covered with denticle-like small spines. P2-4 meri with row of spines on dorsal crest ............................................................................................................................................. U. kaitara Schnabel, 2009

– Abdominal somite 2 smooth on surface. P2-4 meri unarmed or with a few small proximal spines on dorsal crest ......................................................................................................................................................................................... 55

55. Posterior branchial region inflated, with a few distinct spines on posterior lateral portion ............................ ........................................................................................................................................................................ U. turgidus n. sp.

– Posterior branchial region not inflated, with or without denticle-like small spines on posterior lateral portion ........................................................................................................................................................................................... 56

56. Anterolateral spine of carapace and lateral orbital spine separated from each other by U-shape in dorsal view .............................................................................................................................................................. U. sarahae n. sp.

– Anterolateral spine of carapace and lateral orbital spine close to each other, separated by V-shape in dorsal view ......................................................................................................................................................................................... 57

57. Carapace dorsal surface with denticle-like small spines on anterior portion (on hepatic and often on epigastric region). Lateral orbital spine of carapace larger than anterolateral spine .......... U. toka Schnabel, 2009

– Carapace dorsal surface without denticle-like small spines on anterior portion. Lateral orbital spine of carapace subequal to anterolateral spine .................................................................................................... U. volsmar n. sp.

58. Carapace and anterior part of abdominal somites covered with denticles ..................... U. denticulifer n. sp.

– Carapace and abdomen not covered with denticles ................................................................................................. 59

59. Flexor marginal spines of P2-4 dactyli closely arranged and nearly contiguous to one another ..................... ................................................................................................................................................................ U. pronus Baba, 2005

– Flexor marginal spines of P2-4 dactyli loosely arranged .......................................................................................... 60

60. Ultimate spine of P2-4 dactyli distinctly broader than antepenultimate .......................... U. altus Baba, 2005

– Ultimate spine of P2-4 dactyli as slender as or more slender than antepenultimate ........................................ 61

61. Antennal article 4 unarmed .......................................................................................................... U. laurentae n. sp.

– Antennal article 4 with distomesial spine ................................................................................................................... 62

62. Posterior branchial region with dorsolateral projection ...................... U. longicheles Ahyong & Poore, 2004

– Posterior branchial region smooth ................................................................................ U. paenultimus Baba, 2005

63. P2-4 dactyli with flexor marginal spines perpendicularly directed .................................................................... 64

– P2-4 dactyli with flexor marginal spines obliquely directed ................................................................................... 66

64. Branchial lateral margin of carapace with row of small spines ........................... U. yaldwyni Schnabel, 2009

– Branchial lateral margin of carapace smooth and unarmed ................................................................................... 65

65. Anterolateral spine of carapace very close to lateral orbital spine (nearly contiguous at base in dorsal view). Eyes distally narrowed. Antennal article 2 with distinct distolateral spine .................................... U. poorei n. sp.

– Anterolateral spine of carapace distinctly separated from lateral orbital spine in dorsal view. Eyes slightly swollen distally. Antennal article 2 without distolateral spine [characters of the type material (ZSIC 2340- 2350/10) confirmed by K. K. Tiwari, personal comm.] ................... U. bacillimanus Alcock & Anderson, 1899

66. Carapace lateral margin with anterolateral spine only, no additional spine (tubercle-like small spines may be present) ............................................................................................................................................................................. 67

– Carapace lateral margin with distinct spine(s) in addition to anterolateral spine ............................................. 72

67. Carapace distinctly longer than broad. Rostrum not reaching cornea ...................................... U. minor n. sp.

– Carapace as long as or shorter than broad. Rostrum overreaching cornea ........................................................ 68

68. Carapace dorsal surface with tubercle-like very small spines along lateral margin. Pereopods 1-4 spinous, especially P1 carpus covered with small spines; P2-4 meri and carpi with row of dorsal/extensor spines ........ ........................................................................................................................................................................ U. obtusus n. sp.

– Carapace dorsal surface smooth. P1 carpus with distal spines only; P2-4 meri and carpi unarmed ............ 69

69. P2-4 dactyli with at most 4 loosely arranged spines proximal to prominent penultimate spine .................... ....................................................................................................................................................... U. tomentosus Baba, 1974

– P2-4 dactyli with more than 9 closely arranged spines proximal to prominent penultimate spine .............. 70

70. Rostrum as long as broad. P1 merus much shorter than carapace (0.7 ×) ................. U. brevipes Baba, 1990

– Rostrum longer than broad. P1 merus about as long as or longer than carapace ............................................. 71

71. Sternite 4 with anterolateral angle rounded or produced to small spine not reaching anterior end of ster- nite 3. Carapace pinkish red on anterior part, whitish on remaining carapace, pale on rostrum; abdomen whitish; P1 pale pinkish red, other pereopods much paler ................................ U. babai Ahyong & Poore, 2004

– Sternite 4 with anterolateral angle produced to spine reaching anterior end of sternite 3. Body and appen- dages reddish ........................................................................................................ U. parilis Cabezas, Lin & Chan, 2011

72. Carapace lateral margin with 1 spine (may be followed by 1 or 2 very small spines) in addition to antero- lateral spine ............................................................................................................................................................................ 73

– Carapace lateral margin with more than 1 spine in addition to anterolateral spine ......................................... 77

73. Carapace lateral spine situated at anterior end of branchial margin ................................................................. 74

– Carapace lateral spine situated at midlength of carapace lateral margin ............................................................. 75

74. Branchial lateral margins subparallel. Antennal articles 4 and 5 unarmed .................... U. adiastaltus n. sp.

– Branchial lateral margins convex. Antennal articles 4 and 5 each with distomesial spine .................................. ................................................................................................................................................................... U. alius Baba, 2005

75. Midlateral spine of carapace small. P2-4 dactyli with 5 loosely arranged spines proximal to prominent penultimate spine, ultimate much broader than antepenultimate [characters confirmed by examination of the syntypes, ZMA De 101.693] .............................................................................................. U. suluensis Van Dam, 1933

– Midlateral spine of carapace prominent. P2-4 dactyli with more than 10 closely arranged spines, ultimate subequally slender as antepenultimate ........................................................................................................................... 76

76. Antennal flagellum extending far beyond end of P1 merus ...................................... U. valdiviae Balss, 1913a

– Antennal flagellum barely reaching end of P1 merus ...................................................... U. raymondi Baba, 2000

77. Sternite 3 without median notch on anterior margin (very small or ill-defined notch may be present) .. 78

– Sternite 3 with median notch separating distinct or obsolescent submedian spines on anterior margin ... 81

78. Carapace 1.7 × broader than long, lateral margin with prominent spine at anterior two-fifths of length, preceded by a few small spines and followed by more than 10 very small spines. Lateral orbital spine well developed but smaller than anterolateral spine. Sternite 3 with shallowly concave anterior margin with tiny median notch ........................................................................................................................................... U. vulcanus n. sp.

– Carapace 1.1-1.2 × broader than long, lateral margin with 4 or 5 acute, posteriorly diminishing spines along branchial region. Lateral orbital spine much smaller than anterolateral spine. Sternite 3 with V-shaped ante- rior margin ............................................................................................................................................................................. 79

79. Carapace dorsal surface with scale-like striae ............................................................................ U. strigosus n. sp.

– Carapace dorsal surface with no scale-like striae on posterior half (small scales may be present on anterior half) ......................................................................................................................................................................................... 80

80. Anterolateral margin of sternite 4 about as long as posterolateral margin. Mxp3 merus unarmed .............. ......................................................................................................................................................... U. dentatus Balss, 1913a

– Anterolateral margin of sternite 4 1.5 × longer than posterolateral margin. Mxp3 merus with distolateral spine and a few small flexor marginal spines .............................................................. U. occultispinatus Baba, 1988

81. P2 carpus with more than 1 spine on extensor margin ......................................................................................... 82

– P2 carpus unarmed or with at most 1 small distal spine on extensor margin .................................................... 89

82. Carapace lateral margin with 5 spines (including anterolateral spine) .............................................................. 83

– Carapace lateral margin with 6 or more spines (including anterolateral spine) ................................................ 84

83. Carapace dorsal surface smooth but transverse row of small epigastric spines. P1 merus with field of oblique row of 3 closely arranged spines on mesial proximal surface ...................................... U. quinarius n. sp.

– Carapace dorsal surface granulose, without epigastric spines. P1 merus without field of oblique row of 3 closely arranged spines on mesial proximal surface ...................................................................... U. vegrandis n. sp.

84. P2-4 dactyli with 6 loosely arranged flexor marginal spines proximal to pronounced penultimate spine ... .................................................................................................................................................. U. japonicus Ortmann, 1892

– P2-4 dactyli with more than 10 closely arranged (nearly contiguous) flexor marginal spines proximal to pronounced penultimate spine ......................................................................................................................................... 85

85. Antennal scale terminating in distal end of antennal article 5. P2 merus with row of spines along ven- tromesial margin ................................................................................................................ U. nanophyes McArdle, 1901

– Antennal scale overreaching antennal article 5. P2 merus without row of spines along ventromesial mar- gin ............................................................................................................................................................................................ 86

86. Carapace dorsal surface thickly covered with setae; lateral marginal spines small .......... U. echinatus n. sp.

– Carapace dorsal surface barely or sparsely setose; lateral marginal spines well-developed ............................. 87

87. Row of epigastric spines. Mxp3 ischium with small spine near distal end of flexor margin ............................ ....................................................................................................................................................................... U. karubar n. sp.

– Row of epigastric spines absent. Mxp3 ischium without spine near distal end of flexor margin .................. 88

88. Carapace lateral spines directed anteriorly. Abdominal somite 1 convex from anterior to posterior. Mxp3 ischium not rounded on distal end of flexor margin ........................................................................ U. alophus n. sp.

– Carapace lateral spines directed anterolaterally. Abdominal somite 1 with transverse ridge. Mxp3 ischium rounded on distal end of flexor margin ...................................................................................... U. longior Baba, 2005

89. Sternite 4 with posterolateral margin as long as or longer than anterolateral margin .................................. 90

– Sternal 4 with posterolateral margin shorter than anterolateral margin ............................................................. 96

90. Carapace dorsal surface with tubercles and small spines on anterior and lateral portions .............................. ............................................................................................................................................................... U. tuberculatus n. sp.

– Carapace dorsal surface unarmed or with row of epigastric spines ..................................................................... 91

91. P2-4 dactyli with 4 or 5 loosely arranged spines proximal to prominent penultimate spine ........................... ...................................................................................................................................................................... U. grandior n. sp.

– P2-4 dactyli with 12-18 closely arranged spines proximal to prominent penultimate spine .......................... 92

92. Branchial lateral margin with 4 strong spines. P1 merus with oblique row of 3 closely arranged spines on mesioproximal surface ........................................................................................................................................................ 93

– Branchial lateral margin with 5-7 posteriorly diminishing spines. P1 merus lacking oblique row of 3 closely arranged spines on mesioproximal surface .................................................................................................................... 94

93. Pterygostomian flap with spine below linea anomurica between second and third lateral spines of cara- pace. P1 merus with 4 strong ventromesial spines .............................................................................. U. floccus n. sp.

– Pterygostomian flap without spine below linea anomurica between second and third lateral spines of cara- pace. P1 merus with 2 strong ventromesial spines (occasionally 1 or 2 additional small spines) ......................... ........................................................................................................................................................................... U. dualis n. sp.

94. Antennal article 5 with distomesial spine. Antepenultimate spine of P2-4 dactyli long relative to breadth (length-breadth ratio, 3.9-4.8) .............................................................................................................. U. kareenae n. sp.

– Antennal article 5 unarmed. Antepenultimate spines of P2-4 dactyli short relative to breadth (length- breadth ratio, 2.0-2.9) .......................................................................................................................................................... 95

95. Gastric region anteriorly sloping down on to rostrum. Antennal scale terminating in distal quarter of article 5. Ultimate spines of P2-4 dactyli as slender as antepenultimate ...................... U. levicrustus Baba, 1988

– Gastric region preceded by depressed rostrum. Antennal scale reaching first or second segment of flagel- lum. Ultimate spines of P2-4 dactyli more slender than antepenultimate ............................... U. depressus n. sp.

96. P2-4 dactyli with 5-7 slender, loosely arranged spines proximal to pronounced penultimate spine ......... 97

– P2-4 dactyli with more than 10 slender, closely arranged spines proximal to pronounced penultimate spine .................................................................................................................................................................................................. 99

97. Transverse row of spines across epigastric region ..................................... U. undecimspinosus Kensley, 1977

– No spine on epigastric region ........................................................................................................................................ 98

98. P2-4 dactyli with ultimate flexor marginal spine much broader than antepenultimate .................................... ......................................................................................................................................................................... U. wolffi Baba, 2005

– P2-4 dactyli with ultimate flexor marginal spine more slender than antepenultimate ........................................ ............................................................................................................................................. U. belos Ahyong & Poore, 2004

99. Eyes strongly narrowed distally ............................................................................................ U. micrommatus n. sp.

– Eyes equally broad or somewhat narrowed proximally and distally ................................................................... 100

100. Field of more than 10 spines across epigastric region ................................ U. cardus Ahyong & Poore, 2004

– No distinct spine on epigastric region ....................................................................................................................... 101

101. Pterygostomian flap anteriorly roundish with small spine. P2 propodus with 15 single spines proximal to pair of terminal spines ............................................................................................................................ U. spinulus n. sp.

– Pterygostomian flap anteriorly angular, produced to spine. P2 propodus with 1-5 single spines proximal to pair of terminal spines ...................................................................................................................................................... 102

102. Branchial lateral margin with 5 small spines; no spine on hepatic margin. Antennal scale terminating in distal end of article 5 ................................................................................................................................ U. dissitus n. sp.

– Branchial lateral margin with 4 or 5 well-developed, acute spines. Antennal scale overreaching distal end of article 5 ................................................................................................................................................................................. 103

103. Branchial lateral margin with 5 well-developed spines. P2 merus with row of small spines on dorsal mar- gin ......................................................................................................................... U. worrorra McCallum & Poore, 2013

– Branchial lateral margin with 4 well-developed spines. P2 merus unarmed on dorsal margin ......................... ................................................................................................................................................... U. crassipes Van Dam, 1939

104. Eyes 3 × longer than broad ........................................................................... U. novaezelandiae Borradaile, 1916

– Eyes relatively short, at most 2 × longer than broad ............................................................................................... 105

105. P2-4 dactyli with ultimate spine more slender than penultimate ................................................................... 106

– P2-4 dactyli with ultimate spine subequal to or larger than penultimate .......................................................... 153

106. P2-4 propodi without flexor marginal spines ............................................. U. patulus Ahyong & Poore, 2004

– P2-4 propodi with flexor marginal spines ................................................................................................................. 107

107. P4 propodi with pair of terminal spines only (P2 and P3 may have a few single spines proximal to terminal pair) ....................................................................................................................................................................................... 108

– P2-4 propodi with row of flexor marginal spines, terminal single or paired .................................................... 127

108. Epigastric spines present. Ultimate spine of P2-4 dactyli slightly more slender than penultimate ........ 109

– Epigastric spines absent. Ultimate spine of P2-4 dactyli much more slender than penultimate ................. 114

109. Three well-developed spines on anterior third of carapace lateral margin. Antennal scale overreaching midlength of article 5. Article 4 with distomesial spine ............................................................................................ 110

– Two well-developed spines (and 0-2 small spines between) on anterior third of carapace lateral margin. Antennal scale not reaching midlength of article 5. Article 4 unarmed ............................................................... 112

110. Epigastric region with 2 pairs of spines, median pair small ................................................. U. mesodme n. sp.

– Epigastric region with pair of spines .......................................................................................................................... 111

111. Carapace lateral spines directed distinctly anterolaterally. Antennal scale barely reaching end of article 5, article 5 unarmed ................................................................................................................................ U. trispinatus n. sp.

– Carapace lateral spines directed slightly anterolaterally. Antennal scale overreaching article 5, article 5 with distomesial spine ................................................................................................................................ U. paraplesius n. sp.

112. Epigastric region with pair of spines flanked by 2 small spines. Two small but distinct spines between 2 strong anterior spines of carapace lateral margin. Female pleuron of abdominal somite 3 strongly tapering laterally ............................................................................................................................................................ U. clarki n. sp.

– Epigastric region with pair of spines only. One or two tiny or obsolescent (or obsolete) spines between 2 strong anterior spines of carapace lateral margin. Female pleuron of abdominal somite 3 moderately tapering laterally ................................................................................................................................................................................. 113

113. Antennal article 2 with strong distolateral spine. Posterior branchial margin with 4 or 5 spines ................ ...................................................................................................................................................................... U. defayeae n. sp.

– Antennal article 2 with small distolateral spine. Posterior branchial margin with 1 spine at anterior end ..... ..................................................................................................................................................................... U. corbariae n. sp.

114. Carapace with rounded anterolateral corner, lacking anterolateral spine. P4 merus longer than P3 merus ................................................................................................................................................................. U. cylindropus n. sp.

– Carapace with anterolateral spine. P4 merus shorter than or subequal to P3 merus ..................................... 115

115. Carapace lateral margin without spine other than anterolateral spine .......................................................... 116

– Carapace lateral margin with spines in addition to anterolateral spine ............................................................. 121

116. Anterolateral spine of carapace reduced to acuminate angle or very small short spine. Antennal article 2 laterally unarmed ..................................................................................................................................... U. enriquei n. sp.

– Anterolateral spine of carapace distinct. Antennal article 2 with distinct distolateral spine ........................ 117

117. Sternite 3 without median notch on anterior margin. Antennal article 4 unarmed ............ U. eratus n. sp.

– Sternite 3 with median notch on anterior margin. Antennal article 4 with distomesial spine ..................... 118

118. Anterolateral spine of carapace distinctly larger than lateral orbital spine ................................................... 119

– Anterolateral spine of carapace small, subequal to lateral orbital spine ............................................................ 120

119. P2-4 dactyli with 6 perpendicularly directed spine on flexor margin. Mxp3 merus with distinct distolate- ral spine ........................................................................................................................................... U. amabilis Baba, 1977

– P2-4 dactyli with 9 or 10 obliquely directed spines on flexor margin. Mxp3 merus without distolateral spine .................................................................................................................................................. U. brachycarpus n. sp.

120. Gastric region with 2 broad prominences. P2-4 dactyli longer than carpi. P4 merus as long as P3 merus ......................................................................................................................................................... U. rutua Schnabel, 2009

– Gastric region without prominences. P2-4 dactyli as long as carpi. P4 merus 0.8 × as long as P3 merus ...... ...................................................................................................................................................................... U. philippei n. sp.

121. No spine on posterior half of carapace lateral margin ....................................................................................... 122

– Spines present on posterior half of carapace lateral margin ................................................................................. 123

122. Carapace lateral margin with 4 spines behind anterolateral spine, anterior 2 small. Antennal scale over- reaching antennal article 5 .......................................................................................................... U. zezuensis Kim, 1972

– Carapace lateral margin with 2 spines behind anterolateral spine, anterior spine occasionally obsolete. An- tennal scale barely reaching end of antennal article 5 .................................................. U. joloensis Van Dam, 1939

123. Anterolateral spine of carapace smaller than lateral orbital spine ...................................... U. bertrandi n. sp.

– Anterolateral spine of carapace larger than lateral orbital spine ......................................................................... 124

124. Antennal article 2 unarmed. Flexor marginal spines of P2-4 dactyli somewhat obliquely directed ............ ........................................................................................................................................................... U. convexus Baba, 1988

– Antennal article 2 with distinct distolateral spine. Flexor marginal spines of P2-4 dactyli perpendicularly directed ................................................................................................................................................................................. 125

125. Carapace lateral margin with 12-18 small but distinct spines behind anterolateral spine .............................. ...................................................................................................................................................................... U. spinosior n. sp.

– Carapace lateral margin with 5 or 6 spines behind anterolateral spine (2 small hepatic marginal, 3 or 4 rela- tively large branchial marginal) ....................................................................................................................................... 126

126. Branchial lateral margin with 4 spines. P1 merus with a few spines on ventral surface. Antennal article 5 with distomesial spine only ........................................................................................................................ U. annae n. sp.

– Branchial lateral margin with 3 spines. P1 merus with row of 5 spines on ventromesial margin and 3 spines on proximal ventral surface. Antennal article 5 with 2 ventromesial spines in addition to distomesial spine .. ...................................................................................................................................... U. oxymerus Ahyong & Baba, 2004

127. Terminal spines of P2-4 propodi single, not paired ............................... U. gracilimanus ( Henderson, 1885)

– Terminal spines of P2-4 propodi paired .................................................................................................................... 128

128. Carapace lateral margin without distinct spine except for anterolateral spine ........................................... 129

– Carapace lateral margin spinous ................................................................................................................................. 132

129. Sternite 3 without median notch on anterior margin ............................................................. U. tafeanus n. sp.

– Sternite 3 with median notch ....................................................................................................................................... 130

130. P1 ischium with subterminal spine on ventromesial margin. P2 merus with row of small spines along ventromesial margin ................................................................................................................ U. denticulisquama n. sp.

– P1 ischium unarmed on ventromesial margin. P2 merus with smooth ventromesial margin ..................... 131

131. Antennal scale extending far beyond eye, reaching second segment of flagellum. Antennal article 5 with distomesial spine ................................................................................................. U. taylorae McCallum & Poore, 2013

– Antennal scale not overreaching eye, terminating in distal third of article 5. Antennal article 5 unarmed ... .......................................................................................................................................................... U. indicus Alcock, 1901

132. Lateral limit of orbit rounded, lacking lateral orbital spine ........................................................... U. smib n. sp.

– Lateral orbital spine distinct ......................................................................................................................................... 133

133. Anterior margin of sternite 3 without distinct median notch and pair of spines (very small or obsolescent notch may be present) ...................................................................................................................................................... 134

– Anterior margin of sternite 3 with distinct median notch and/or pair of spines ............................................ 141

134. Lateral marginal spines of carapace small (other than anterolateral spine) ................................................. 135

– Lateral marginal spines of carapace well-developed (at least one of spines well developed) ....................... 136

135. Rostrum with subapical spine on each side. Antennal articles 4 and 5 each with strong distomesial spine ........................................................................................................................................................ U. perpendicularis n. sp.

– Rostrum without subapical spine. Antennal articles 4 and 5 each with obsolescent distomesial spine .......... ........................................................................................................................................................................ U. lanatus n. sp.

136. Branchial margin with 4 spines. Antennal articles 4 and 5 each with strong distomesial spine. P2-4 dactyli with 18-21 spines on flexor margin ..................................................................................................... U. modicus n. sp.

– Branchial margin with 6 or more spines. Antennal articles 4 and 5 each unarmed or with obsolescent dis- tomesial spine. P2-4 dactyli with 10-14 spines on flexor margin ........................................................................... 137

137. No spine on hepatic lateral margin between anterolateral and anteriormost branchial spine. Antennal scale falling short of apex of rostrum ........................................................................................................................... 138

– Spines present on hepatic lateral margin between anterolateral and anteriormost branchial spines. Antennal scale reaching or overreaching apex of rostrum ......................................................................................................... 139

138. Dorsal surface of carapace with small spine directly behind rostrum and directly behind anterolateral spine. Sternite 3 with deeply V-shaped anterior margin. P2-4 dactyli shorter than carpi ...... U. posticus n. sp.

– No spine behind rostrum and anterolateral spine. Sternite 3 with shallowly V-shaped anterior margin with very small median notch. P2-4 dactyli longer than carpi ..................................................................... U. exilis n. sp.

139. Anterior margin of sternite 3 transverse along median third, not V-shaped. Sternal plastron strongly broadened posteriorly, sternite 7 broadest ............................................................................................ U. duplex n. sp.

– Anterior margin of sternite 3 widely V-shaped with very small median notch. Sternal plastron gently broa- dened posteriorly, sternite 6 broadest ........................................................................................................................... 140

140. Carapace lateral margin with 8 or 9 spines, those on posterior branchial margin narrow at base. Antero- lateral spine slightly larger than lateral orbital spine .................................................................. U. macrolepis n. sp.

– Carapace lateral margin with 12 spines, those on posterior branchial margin broad at base (distally laciniate or bifurcate). Anterolateral spine much larger than lateral orbital spine ....................................... U. zigzag n. sp.

141. Anterior margin of sternite 3 with pair of small median spines contiguously placed side by side ......... 142

– Anterior margin of sternite 3 with distinct median notch separating distinct or obsolescent submedian spines .................................................................................................................................................................................... 143

142. Carapace subtriangular in dorsal view (greatest breadth measured at posterior third, 2.2 × distance between anterolateral spines). Branchial marginal spines short and broad at base (broad triangular). P2-4 meri with spines on dorsal margin ............................................................................ U. triangularis Miyake & Baba, 1967

– Carapace moderately broadened posteriorly (greatest breadth measured at posterior third, 1.8 × distance between anterolateral spines). Branchial marginal spines small. P2-4 meri unarmed on dorsal margin ........... ...................................................................................................................................................................... U. palmaris n. sp.

143. Lateral margin of carapace with small spines (other than anterolateral spine) ........................................... 144

– Lateral margin of carapace with well-developed or distinct spine(s) (at most one of spines distinct in low magnification) ..................................................................................................................................................................... 145

144. Anterolateral spine of carapace small, subequal to lateral orbital spine. Rostrum with subapical spine on each side. P1 ischium without subterminal spine on ventromesial margin ............................................................... ............................................................................................................................ U. multispinosus Ahyong & Poore, 2004

– Anterolateral spine of carapace distinctly larger than lateral orbital spine. Rostrum without subapical spine. P1 ischium with subterminal spine on ventromesial margin ......................................... U. murrayi Tirmizi, 1964

145. Lateral orbital spine of carapace relatively large, subequal to or slightly smaller than anterolateral spine. ................................................................................................................................................................................................. 146

– Lateral orbital spine of carapace much smaller than anterolateral spine .......................................................... 147

146. Last lateral marginal spine of carapace closer to posterior end than to preceding spine. Antennal scale barely reaching distal end of article 5, article 5 unarmed. P2-4 dactyli with 9 or 10 closely arranged, perpen- dicularly directed spines proximal to slender ultimate spine ............................................................. U. beryx n. sp.

– Last lateral marginal spine of carapace much closer to preceding spine than to posterior end. Antennal scale overreaching article 5, article 5 with strong distomesial spine. P2-4 dactyli with 5-7 loosely arranged, obliquely directed spines proximal to slender ultimate spine ......................................................... U. vicinus n. sp.

147. Antennal scale terminating at most in distal end of article 5 (excluding distal spine); article 5 unarmed or without distinct spine ....................................................................................................................................................... 148

– Antennal scale overreaching article 5 (excluding distal spine); article 5 with strong distomesial spine .... 149

148. Anterolateral margin of sternite 4 with rounded anterior end. P1 ischium smooth on ventromesial mar- gin ............................................................................................................................................................. U. baeomma n. sp.

– Anterolateral margin of sternite 4 with a few small spines on anterior end. P1 ischium with well-developed subterminal spine on ventromesial margin ..................................................................................... U. elongatus n. sp.

149. One of lateral spines of carapace distinct (recognizable under low magnification), other spines small. P1 ischium without subterminal spine on ventromesial margin .............................................. U. magnipedalis n. sp.

– Most of lateral spines of carapace well-developed. P1 ischium with subterminal spine on ventromesial margin ................................................................................................................................................................................... 150

150. Hepatic margin (between anterolateral and anteriormost branchial marginal spines) unarmed. Pterygos- tomian flap with distinct spine between anteriorly produced spine and anterior end of linea anomurica ........ .............................................................................................................................................................. U. crassior Baba, 1990

– Hepatic margin (between anterolateral and anteriormost branchial marginal spines) spinous. Pterygosto- mian flap without spine between anteriorly produced spine and anterior end of linea anomurica .............. 151

151. A few small spines on dorsal surface of hepatic region. P1 merus strongly spiny, with row of 3 obliquely arranged spine on proximal mesial face. P2 merus with row of spines along ventromesial margin .................... ..................................................................................................................................................................... U. lumarius n. sp.

– No spine on dorsal surface of hepatic region. P1 merus weakly spiny, without row of 3 closely arranged spines on proximal mesial face. P2 merus smooth along ventromesial margin .................................................. 152

152. P2-4 dactyli strongly narrowed distally, with 6-7 flexor marginal spines including slender terminal. An- tennal scale overreaching antennal peduncle by full length of article 5 .................................... U. seductus n. sp.

– P2-4 dactyli proportionately broad distally, with 9 flexor marginal spines including slender terminal. Anten- nal scale slightly overreaching antennal peduncle (reaching at most second segment of flagellum) .................. ......................................................................................................................................... U. tridentatus ( Henderson, 1885)

153. P2-4 propodi unarmed on flexor margin .............................................................................................................. 154

– P2-4 propodi with pair of terminal spines or row of spines on flexor margin ................................................. 158

154. Lateral margin of carapace with distinct spines in addition to anterolateral spine .................................... 155

– Lateral margin of carapace with anterolateral spine only ...................................................................................... 156

155. P2-4 dactyli with 8 long, obliquely directed spines ...................................................... U. foulisi Kensley, 1977

– P2-4 dactyli with 19-22 short, perpendicularly directed spines ..................................... U. crosnieri Baba, 1990

156. Anterolateral spine of carapace well developed, distinctly overreaching rounded lateral orbital angle ...... ........................................................................................................................................ U. longvae Ahyong & Poore, 2004

– Anterolateral spine of carapace small, not overreaching rounded, angular or spiniform lateral orbital angle ................................................................................................................................................................................................ 157

157. P2-4 dactyli strongly curving with angle of 90°. P1 fingers directed anterolaterally [Characters verified by examination of type material, 1966.2.3.41-42] ...................................................... U. onychodactylus Tirmizi, 1964

– P2-4 dactyli moderately curving with angle of 125°. P1 fingers directed straight forward ................................. ................................................................................................................................................... U. setosidigitalis Baba, 1977

158. P2-4 propodi with pair of terminal spines only on flexor margin ............. U. calcar Ahyong & Poore, 2004

– P2-4 propodi with row of spines on flexor margin, distalmost single or paired (in some species, P4 propodus with terminal pair only) .................................................................................................................................................... 159

159. Anterior margin of sternite 3 without distinct median notch and submedian spines (ill-defined median notch and obsolescent submedian spines may be present) ..................................................................................... 160

– Anterior margin of sternite 3 with pair of median spines or well-defined median notch separating distinct or obsolescent spines ........................................................................................................................................................ 179

160. Carapace lateral margin without distinct spine other than anterolateral spine (fine crenulations or serra- tions may be present) ........................................................................................................................................................ 161 – Carapace lateral margin with distinct spines in addition to anterolateral spine .............................................. 172

161. P2-4 propodi with straight flexor margin ............................................................................................................. 162

– P2-4 propodi with medially or distally convex flexor margin .............................................................................. 165

162. Antennal articles 4 and 5 each with well-developed distomesial spine ......................................................... 163

– Antennal article 4 unarmed, article 5 with obsolescent distomesial spine ....................................................... 164

163. Antennal article 2 unarmed .................................................................... U. laperousazi Ahyong & Poore, 2004

– Antennal article 2 with distinct distolateral spine ............................................... U. latus Ahyong & Poore, 2004

164. P2-4 dactyli with 11 or 12 spines on flexor margin. Anterolateral spine of carapace small, not reaching lateral orbital spine. Sternal plastron as long as broad ................................................................. U. pectoralis n. sp.

– P2-4 dactyli with 6 spines on flexor margin. Anterolateral spine of carapace large, distinctly overreaching lateral orbital spine. Sternal plastron much broader than long [characters confirmed by examination of the male holotype and female paratype, BMNH 1966.2.3.17-18] ...................................... U. gordonae Tirmizi, 1964

165. Sternite 3 with semicircular anterior margin ....................................................................................................... 166

– Sternite 3 with broadly V-shaped anterior margin ................................................................................................. 168

166. Antennal scale terminating in distal end of article 5 ........................... U. edisonicus Baba & Williams, 1996

– Antennal scale extending far beyond end of article 5 ............................................................................................ 167

167. Pterygostomian flap anteriorly produced to distinct spine. Anterolateral spine of carapace directed ante- riorly. Mxp3 crista dentata with denticles tiny on distal half, obsolescent on proximal half ................................. ................................................................................................................................................................ U. norfolkanus n. sp.

– Pterygostomian flap with tiny spine at anterior terminus. Anterolateral spine of carapace directed ante- romesially. Mxp3 crista dentata with denticles along entire length .................................................. U. latior n. sp.

168. P1 merus spinous mesially and distally. P2-4 meri with row of spines on dorsal margin ............................... ..................................................................................................................................... U. hesperius Ahyong & Poore, 2004

– P1 merus barely or very weakly spinous. P2-4 meri unarmed or irregular with obsolescent eminences on dorsal margin ...................................................................................................................................................................... 169

169. P2-4 dactyli with perpendicularly directed spines on flexor margin ................................................................... ........................................................................................................................................................ U. pedanomastigus n. sp.

– P2-4 dactyli with obliquely directed spines on flexor margin .............................................................................. 170

170. P2-4 dactyli with penultimate spine much more distant from ultimate than from antepenultimate. Anten- nal scale terminating at distal end of article 5 ...................................................................................... U. shanei n. sp.

– P2-4 dactyli with penultimate spine equidistant between ultimate and antepenultimate. Antennal scale extending beyond article 5 ............................................................................................................................................... 171

171. Anterolateral spine of carapace directed anterolaterally. Carapace with fine non-plumose setae. Rostrum with small distal spine(s) on lateral margin ................................................................................. U. senticarpus n. sp.

– Anterolateral spine of carapace directed anteriorly. Carapace covered with plumose setae. Rostrum smooth on lateral margin ..................................................................................................................................... U. plumella n. sp.

172. P2-4 propodi with straight flexor margin ............................................................ U. magnispinatus Baba, 1977

– P2-4 propodi with medially or distally convex flexor margin .............................................................................. 173

173. Epigastric region with transverse row of spines .................................................................................................. 174

– Epigastric region unarmed ............................................................................................................................................ 177

174. Antennal articles 4 and 5 unarmed ............................................................................... U. ensirostris Parisi, 1917

– Antennal articles 4 and 5 each with distomesial spine ........................................................................................... 175

175. Branchial marginal spines regularly arranged, subequally spaced. Crista dentata of Mxp3 with distally diminishing denticles ............................................................................................... U. zeidleri Ahyong & Poore, 2004

– Branchial marginal spines irregularly arranged, widely spaced between anterior and posterior branchial margins. Crista dentata of Mxp3 with evenly minute denticles ............................................................................. 176

176. Hepatic lateral margin with spinules. Mesial margin of P1 merus with several strong spines. P2-4 propodi each with spines only on distal projection of flexor margin ................................... U. insignis ( Henderson, 1885)

– Hepatic lateral margin smooth and unarmed. Mesial margin of P1 merus with strong median spine other than distal spine. P2-4 propodi each with another spine distantly proximal to those on distal projection ....... .............................................................................................................................................. U. spinulosus Dong & Li, 2016

177. P2-3 meri with spines on dorsal margin. P1 carpus with row of dorsal spines ................................................. .................................................................................................. U. hamatus Khodkina, in Zarenkov & Khodkina, 1983

– P2-3 meri unarmed on dorsal margin. P1 carpus without row of dorsal spines .............................................. 178

178. Rostrum without lateral spines. Sternite 3 having anterior margin medially concave, without median sinus. Antennal articles 4 and 5 unarmed. P1 fingers directed anterolaterally [characters confirmed by exami- nation of male holotype, ZMA De. 101.666] ............................................................... U. xipholepis Van Dam, 1933

– Rostrum with a few small lateral spines. Sternite 3 having anterior margin V-shaped, with ill-defined me- dian sinus. Antennal articles 4 and 5 each with distomesial spine. P1 fingers directed straight forward ........... .................................................................................................................................. U. subsolanus Ahyong & Poore, 2004

179. Carapace broader than long ..................................................................................................................................... 180

– Carapace about as long as or longer than broad ...................................................................................................... 183

180. Carapace lateral margin with anterolateral spine only ...................................................................................... 181

- Carapace lateral margin spinous .................................................................................................................................. 182

181. Anterior margin of sternite 3 shallowly concave, with U-shaped median notch separating small subme- dian spines. Antennal articles 4 and 5 unarmed. P2 carpus as long as P2 dactylus [characters confirmed by examination of the male holotype, NSMT-Cr. 6177] ............................................................... U. glaber Baba, 1981

– Anterior margin of sternite 3 broadly V-shaped, with semicircular median notch separating obsolescent submedian spines. Antennal articles 4 and 5 each with small distomesial spine. P2 carpus 1.6 × longer than P2 dactylus [characters confirmed by examination of the ovigerous female holotype, BMNH 1966.2.3.43] .... .............................................................................................................................................................. U. siraji Tirmizi, 1964

182. Pterygostomian flap with 2 spines on dorsal margin between anterior terminal spine and anterior end of linea anomurica. Sternite 3 with distinct submedian spines. P2-4 dactyli with 9-11 flexor marginal spines .... ............................................................................................................................... U. paracrassior Ahyong & Poore, 2004

– Pterygostomian flap smooth on dorsal margin between anterior terminal spine and anterior end of linea anomurica. Sternite 3 without submedian spines. P2-4 dactyli with 6 or 7 flexor marginal spines. ................... ....................................................................................................................................................................... U. megistos n. sp.

183. Row of flexor marginal spines of P2-4 propodi distally ending in single spine ........................................... 184

– Row of flexor marginal spines of P2-4 propodi distally ending in pair of spines ............................................. 188

184. Carapace dorsal surface and P1 granulose ............................................................... U. soyomaruae Baba, 1981

– Carapace dorsal surface and P1 smooth (epigastric spines may be present) .................................................... 185

185. Pair of spines on epigastric region ......................................................................................................................... 186

– No spine on epigastric region (pair of tuberculate ridges may be present) ...................................................... 187

186. P2-4 relatively slender: P2 merus 5.2-6.5 × longer than broad. Flexor margins of P2-4 propodi having distalmost spine remote from juncture with dactylus (closer to distal second spine or equidistant between juncture and distal second spine) .................................................................................... U. nigricapillis Alcock, 1901

– P2-4 relatively broad: P2 merus 3.7-4.8 × longer than broad. Flexor margins of P2-4 propodi having distal- most spine very close to juncture with dactylus ........................................................................... U. terminalis n. sp.

187. Carapace longer than broad. Antennal article 2 with distinct distolateral spine .... U. stenorhynchus n. sp.

– Carapace as long as broad. Antennal article 2 distolaterally acuminate or with very tiny spine ....................... ................................................................................................................................................................ U. dejouanneti n. sp.

188. Sternite 5 with feebly convex or nearly straight anterolateral margin ........... U. politus ( Henderson, 1885)

– Sternite 5 with distinctly convex anterolateral margin .......................................................................................... 189

189. P4 carpus longer than P3 carpus ............................................................................................ U. longicarpus n. sp.

– P4 carpus as long as or shorter than P3 carpus ....................................................................................................... 190

190. Carapace lateral margin with well-developed spine(s) in addition to anterolateral spine ........................ 191

– Carapace lateral margin with anterolateral spine only, unarmed elsewhere (very small spine(s) or denticles may be present) .................................................................................................................................................................. 197

191. Sternite 4 having anterolateral margin about as long as posterolateral margin .............. U. squamifer n. sp.

– Sternite 4 having anterolateral margin distinctly longer than posterolateral margin ..................................... 192

192. Antennal article 4 with distomesial spine. P1 merus spinous .......................................... U. boisselierae n. sp.

– Antennal article 4 unarmed. P1 merus unarmed .................................................................................................... 193

193. Epigastric region with several small spines .......................................................................................................... 194

– Epigastric region unarmed ............................................................................................................................................ 195

194. Sternite 4 with anterior breadth (measured between left and right anteriorly produced spines) 0.55 × pos- terior breadth (greatest breadth between left and right posterolateral lobes); length of anterolateral margin 0.53-0.56 × distance between left and right anteriorly produced spines .................... U. longioculus Baba, 1990

– Sternite 4 with anterior breadth (measured between left and right anteriorly produced spines) 0.45-0.49 × posterior breadth (greatest breadth between left and right posterolateral lobes); length of anterolateral mar- gin 0.63-0.73 × distance between left and right anteriorly produced spines .............................. U. poupini n. sp.

195. Carapace longer than broad. P1 ischium with small subterminal spine on ventromesial margin ................ ....................................................................................................................................... U. flindersi Ahyong & Poore, 2004

– Carapace as long as broad. P1 ischium unarmed on ventromesial margin ....................................................... 196

196. Cornea slightly inflated. P2-4 meri relatively broad, length-breadth ratio, 3.7-3.9 on P2, 3.4-4.1 on P3, 3.6- 3.8 on P4. P2 merus longer than P3 merus, distinctly shorter than (0.8 × length of) carapace ............................ .................................................................................................................................................................... U. nebulosus n. sp.

– Cornea distinctly inflated. P2-4 meri relatively narrow, length-breadth ratio, 5.0-5.6 on P2, 5.0-5.3 on P3, 4.2-4.6 on P4. P2 merus as long as P3 merus, subequal to or very slightly shorter than carapace ....................... ...................................................................................................................................................... U. sibogae Van Dam, 1933

197. Pair of epigastric spines present .............................................................................................................................. 198

– Epigastric spines absent (pair of tuberculate ridges may be present) ................................................................. 201

198. P2-4 carpi at least slightly shorter than propodi [characters observed in male holotype and in a specimen taken at Lau Back-Arc Basin, 2668 m by Cruise TUIM-06-MV, Dive 140, now in the collection of MNHN]. .......................................................................................................................... U. bicavus Baba & de Saint Laurent, 1992

– P2-4 carpi less than two-thirds length of propodi ....................................................................................... 199

199. Pterygostomian flap with anterior margin sharp angular, ending in distinct spine ........ U. benthaus n. sp.

– Pterygostomian flap with anterior margin roundish, bearing tiny spine ........................................................... 200

200. Sternite 4 granulose on surface. P1 palm granulose on ventral surface. P2-4 dactyli with row of plumose setae along extensor margin ..................................................................................................... U. sagamiae Baba, 2005

– Sternite 4 not granulose on surface. P1 palm smooth on ventral surface. P2-4 dactyli without row of plumose setae along extensor margin ......................................................................... U. pollostadelphus n. sp.

201. P1 ischium with distinct subterminal spine on ventromesial margin ............................................................ 202

– P1 ischium unarmed or with obsolescent or very small subterminal spine on ventromesial margin ........ 205

202. Anterolateral spine of carapace not overreaching lateral orbital spine. P1 merus covered with small spines on ventral surface .......................................................................................................................................... U. psilus n. sp.

– Anterolateral spine of carapace overreaching lateral orbital spine. P1 merus smooth or granulated on ven- tral surface ........................................................................................................................................................................... 203

203. Carapace dorsal surface smooth ............................................................................................... U. granulipes n. sp.

– Carapace dorsal surface granulose .............................................................................................................................. 204

204. Antennal article 5 with distinct distomesial spine. Dactylus-carpus length ratio 0.6 on P2 and P3, 0.7 on P4 .................................................................................................................................................. U. brucei Baba, 1986a

– Antennal article 5 unarmed. Dactylus-carpus length ratio 0.7-0.8 on P2, 0.8-0.9 on P3, 0.9-1.0 on P4 .......... ...................................................................................................................................................... U. maori Borradaile, 1916

205. Sternite 4 with anterolateral angle strongly produced forward, reaching or overreaching anterior end of sternite 3 ............................................................................................................................................................................... 206

– Sternite 4 with anterolateral angle not reaching anterior end of sternite 3 ...................................................... 207

206. Carapace and abdominal somites 1-2 granulated. Submedian spines on anterior margin of sternite 3 contiguous at base ............................................................................................................ U. anatonus Baba & Lin, 2009

– Carapace and abdominal somites smooth. Submedian spines on anterior margin of sternite 3 separated by distinct notch [characters confirmed by reexamination of the male holotype, USNM 150312] .......................... ............................................................................................................................................................ U. acostalis Baba, 1988

207. Sternite 4 having anterolateral margin about as long as posterolateral margin ................ U. salomon n. sp.

– Sternite 4 having anterolateral margin distinctly longer than posterolateral margin ..................................... 208

208. P1 palm with sharply ridged mesial margin. P2-4 dactyli less than one-third length of propodi ................. ........................................................................................................................................... U. brachydactylus Tirmizi, 1994

– P1 palm with roundly ridged mesial margin. P2-4 dactyli distinctly more than one-third length of propodi ................................................................................................................................................................................................ 209

209. Carapace 1.2-1.3 × longer than broad ...................................................................................... U. lacunatus n. sp.

– Carapace nearly as long as broad (at most 1.1 × longer than broad) .................................................................. 210

210. Pterygostomian flap anteriorly produced to spine ............................................................................................. 211

– Pterygostomian flap anteriorly roundish or bluntly angular, with or without tiny spine at anterior terminus ................................................................................................................................................................................................ 215

211. Anterolateral spine of carapace short, not reaching lateral orbital spine ..................... U. similis Baba, 1977

– Anterolateral spine of carapace long, overreaching lateral orbital spine ........................................................... 212

212. Antennal article 2 acuminate at distolateral angle, lacking distinct spine ........................... U. inermis n. sp.

– Antennal article 2 with well-developed distolateral spine .................................................................................... 213

213. Carapace and pterygostomian flap granular on surface. Anterolateral margin of sternite 4 smooth. P2-4 dactyli subequally long as carpi ................................................................................... U. anacaena Baba & Lin, 2009

– Carapace and pterygostomian flap smooth on surface (pair of granulate ridges on epigastric region may be present in large specimens). Anterolateral margin of sternite 4 irregular. P2-4 dactyli much shorter than carpi ....................................................................................................................................................................................... 214

214. Sternite 4 with transverse row of granules on surface. Excavated sternum with angular anterior margin. P2 propodus with 7 or 8 spines along distal half of flexor margin, proximal to pair of terminal spines ............. .......................................................................................................................................... U. litosus Ahyong & Poore, 2004

– Sternite 4 with field of granules on surface. Excavated sternum with rounded anterior margin. P2 propodus with 10-12 spines along entire length of flexor margin, proximal to pair of terminal spines ................................ ....................................................................................................................................... U. bardi McCallum & Poore, 2013

215. P4 merus relatively short, 0.6 × length of P3 merus ........................................................................................... 216

– P4 merus relatively long, 0.8-0.9 × length of P3 merus .......................................................................................... 217

216. Carapace dorsal surface smooth (epigastric region with pair of granulate ridges in large specimens). No ridge along lateral margin of carapace .............................................................. U. empheres Ahyong & Poore, 2004

– Carapace dorsal surface sparsely granulated. Lateral margin of carapace ridged along posterior quarter of length [characters confirmed by reexamination of male holotype, USNM 150458] ............................................... ............................................................................................................................................................ U. comptus Baba, 1988

217. Antennal article 2 with acuminate distolateral angle, without distinct spine. P4 merus 0.9 × length of P3 merus. Pterygostomian flap without spine at anterior terminus ........................................... U. septimus n. sp.

– Antennal article 2 with well-developed distolateral spine. P4 merus 0.8 × length of P3 merus. Pterygosto- mian flap with small spine at anterior terminus ......................................................................................................... 218

218. Dorsal surface of carapace with scattered granules on hepatic and branchial regions; epigastric region with pair of granulate ridges. P1 merus with 2 rows of small, low spines on ventral surface ................................ ............................................................................................................................................... U. orientalis Baba & Lin, 2008

– Dorsal surface of carapace smooth. P1 merus smooth on ventral surface .............................................................. ......................................................................................................................................... U. jawi McCallum & Poore, 2013