Uroptychus paku Schnabel, 2009,

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: 369-371

publication ID




persistent identifier


treatment provided by


scientific name

Uroptychus paku Schnabel, 2009


Uroptychus paku Schnabel, 2009 

Figure 182View FIGURE 182

Uroptychus paku Schnabel, 2009: 562  View Cited Treatment , fig. 12.

TYPE MATERIAL — Holotype: New Zealand, Esperance Rock , Kermadec Ridge, 32°11.10’S, 179°05.20’W, 122-307 m, female ( NIWA 9805). [not examined].GoogleMaps 

MATERIAL EXAMINED — New Caledonia, Norfolk Ridge. BERYX 11 Stn CP52, 23°47.45’S, 168°17.05’E, 430-530 m, 21.X.1992: 1 ♀ 3.4 mm (MNHN-IU-2010-5477). 

DISTRIBUTION„ Kermadec Ridge, and now Norfolk Ridge; 122- 530 m.

DIAGNOSIS — Carapace very slightly shorter than broad, greatest breadth 1.3 × distance between anterolateral spines. Dorsal surface with row of 7 small epigastric spines, pair of small submedian spines on anterior cardiac region and 2 longer spines on posterior branchial region; lateral margins slightly divergent posteriorly, bearing 6 spines, first anterolateral, strong, slightly posterior to level of but overreaching much smaller lateral orbital spine; second small, placed on hepatic margin ventral to level of first and third, third to sixth strong, last (sixth) strongest, situated near posterior end. Rostrum relatively broad triangular, with interior angle of 23°, dorsal surface somewhat concave, length four-fifths that of remaining carapace, breadth about half carapace breadth at posterior carapace margin. Pterygostomian flap anteriorly angular, produced to strong spine, surface with several small spines. Excavated sternum bluntly produced anteriorly, surface strongly ridged in midline; sternal plastron 1.2 × longer than broad; lateral extremities somewhat divergent posteriorly; sternite 3 depressed well, anterior margin moderately excavated, with 2 obsolescent submedian spines flanking small median notch; sternite 4 having anterolateral margins relatively short, about as long as posterolateral margin; anterolateral margin of sternite 5 0.7 × as long as anterolateral margin of sternite 4. Abdominal somite 1 with distinct transverse ridge; somite 2 tergite 2.1 × broader than long, pleural lateral margin strongly concave, anteriorly and posteriorly produced; pleural lateral margin of somite 3 tapering. Telson slightly less than half as long as broad; posterior plate 1.3 × longer than anterior plate, posterior margin distinctly emarginate. Eyes 2.0 × longer than broad, somewhat overreaching midlength of rostrum; lateral margin concave, cornea more than half as long as remaining eyestalk. Ultimate article of antennular peduncle 2.7 × longer than high. Antennal peduncle slightly overreaching eye; article 2 with strong lateral spine; antennal scale overreaching article 5; distal 2 articles each with strong distomesial spine; breadth of article 5 0.8 × height of ultimate article of antennule; flagellum of 10 or 11 segments not reaching distal end of P 1 merus. Mxp1 with bases broadly separated. Mxp3 basis with 1 obsolescent denticle on distal part of mesial ridge; ischium with very small denticle-like spine directly lateral to rounded distal end of flexor margin, crista dentata with small, distally obsolescent denticles; merus 1.7 × longer than ischium, with well-developed distolateral spine accompanying small spine near base, flexor margin sharply ridged with a few distinct spines; carpus with distinct distolateral spine and a few small spines on extensor and lateral faces. P 1 5 × as long as carapace, slender, with spines on merus and carpus; ischium dorsally with procurved spine, ventromesially with well-developed subterminal spine; merus as long as carapace; carpus 1.3 × longer than merus; palm 3.0 × longer than broad, about as long as carpus; fingers feebly crossing distally, length 0.6 × that of palm. P 2-4 short relative to breadth; meri successively shorter posteriorly ( P 3 merus 0.9 × length of P 2 merus, P 4 merus 0.95 × length of P 3 merus), subequally broad and about 2.5 × as long as broad on P 2-4; P 2 merus 0.6 × length of carapace, 0.8 × length of P 2 propodus; P 4 merus as long as or very slightly shorter than P 4 propodus; dorsal margins with row of spines, distalmost with accompanying small spine mesial to it; carpi successively slightly shorter posteriorly; carpus-propodus length ratio, 0.4 on P 2-4; extensor margin with row of 6 spines (5 on left P 4) paralleling row of 4 or 5 smaller spines on lateral surface; propodi successively slightly longer posteriorly; flexor margin with pair of relatively long movable terminal spines only; extensor margin with 3 or 4 spines proximally; dactyli proportionately broad, much longer than carpi (dactylus-carpus length ratio, 1.5 on P 2, 1.7 on P 3 and P 4), 0.6 × length of propodi on P 2-4, flexor margin nearly straight, with row of 10 ( P 2)-12 ( P 3, P 4) obliquely directed spines nearly contiguous to one another, ultimate more slender than antepenultimate, penultimate pronounced, more than 2 × broader than antepenultimate, remainder similar but proximal spines diminishing toward base of article.

REMARKS — The material differs from the holotype in having sternite 4 more produced anteriorly, the pterygostomian flap bearing small spines, the P 2-4 propodi proximally bearing extensor marginal spines and carpi bearing additional row of small spines paralleling the row of extensor marginal spines, and 7 epigastric spines. However, they share nearly all essential features including the long rostrum, a pair of spines on the posterior branchial region and a pair of small spines on the cardiac region. The above-mentioned differences will in all probability be size-related; the type material is small, the carapace length being about half that of the present material.

The relationships with U. sexspinosus Balss, 1913a  are discussed by Schnabel (2009). The spinose carapace lateral margin, spinose P 1-4 and the arrangement of spines on P 2-4 dactyli link the species to U. nanophyes McArdle, 1901  . Uroptychus paku  is readily distinguished from that species by the longer rostrum that is four-fifths as long instead of at most half as long as the remaining carapace; the branchial and cardiac regions each bear a pair of dorsal spines; the P 2-4 propodi bear on the flexor margin a pair of terminal spines only instead of bearing additional row of spines proximal to the distal pair. In addition, the P 2-4 meri in U. paku  bear a terminal spine only on the ventrolateral margin, whereas in U. nanophyes  of more than 5.6 mm (poc) a row of spines are usually present on each of the ventrolateral and ventromesial margins of the P 2 merus, occasionally obsolescent on P 3 and P 4.














Uroptychus paku Schnabel, 2009

Baba, Keiji 2018

Uroptychus paku

SCHNABEL K. E. 2009: 562