Mursia minuta, Spiridonov & Apel, 2007

Spiridonov, Vassily A. & Apel, Michael, 2007, A new species and new records of deep-water Calappidae (Crustacea: Decapoda) from the Indian Ocean with a key to the Mursia Desmarest, 1823 species of the region, Journal of Natural History 41 (45 - 48), pp. 2851-2890 : 2870-2878

Mursia minuta n. sp.

( Figures 2G, H , 4E, F , 8C , 10A–D , 11A, B , 12A, B ) Mursia bicristimana: Laurie 1906, p 355 –356; Galil 1993, p 356–357 (part: specimens deposited in the NHM), Figures 1f , 3j, k , 5c, d [not Mursia bicristimana Alcock and

Anderson, 1894].

Material examined

Holotype: Sri Lanka, Gulf of Manaar , Herdman coll.: one male ( NHM 1907.5.22) . Paratype: Sri Lanka, Gulf of Manaar , Herdman coll.: 1 ov. female ( NHM 1934.1.16.23) .

Non-type material. Laccadives: RIMSS Investigator St. 246, 11 ° 149300N, 74 ° 579150E, 68– 148 fathoms (126–275 m), 15 October 1898: one male ( NHM 1898.8.26.3). Gulf of Aden: 13 ° 22.49N, 46 ° 42.99E, RV Akademik Petrovsky, Cruise 14, St. 35, depth 87 m, Sigsbee trawl, D. L. Ivanov and B. V. Mezhov coll., 26 November 1983: one male (moult cast) ( ZMMU Ma 5351); 15 ° 529N, 52 ° 239 E, RV Akademik Kovalevsky, St. 657, depth 83 m, muddy sand, beam trawl, V. V. Murina coll., 11 September 1966: two males ( ZMMU Ma 3902) (freshly moulted; identified as Mursia armata bicristimana by N. A. Zarenkov) .

Type locality

Gulf of Manaar, Sri Lanka.

Etymology

The epithet ‘‘ minuta ’’ (Latin for ‘‘small’’) refers to the body size of the species which is much smaller than most other species within Mursia .

Size

Maximum carapace length does not exceed 20 mm, carapace width excluding lateral spine not more than 25 mm in the material examined. Exact size data are as follows. Holotype: CL517.1 , CW521.7 , MCW 528.0, P 3529.9 mm. Female paratype: CL516.8 , CW520.4 , MCW 525.4 mm (tips of lateral spines broken). Male from the Laccadive Islands: CL519.5 ; CW524.1 ; MCW532.4 ; P3536.6. Male from the Gulf of Aden ( Akademik Petrovsky St. 35): CL 517.0 mm, CW 526.0 mm, MCW527.4 , SL 3.5 mm. Male from Akademik Kovalevsky St. 657: CL 513.0, CW516.9 , MCW520.5 .

Habitat and vertical range

For the type specimens from the Gulf of Manaar no ecological data are available, but due to the fact that the material originates from a study of the pearl oyster banks it can be assumed that they probably originate from relatively shallow waters. The specimen from the Laccadives ( NHM 1898.8.26.3) is from a station with sandy/stony bottom and a depth range of 124–271 m. The specimens from the Gulf of Aden have been collected on muddy sand at depths of 83 and 87 m.

Distribution

Gulf of Aden, Laccadive Islands, Gulf of Manaar.

Description (based on holotype)

Carapace transversally oval, convex, ca 1.65 times broader than long (counting lateral spines) and ca 1.25 times broader than long not counting lateral spines. Dorsal surface coarsely granular excepting frontal and orbital region, which is finely granulated. A longitudinal row of four blunt tubercles (protuberances according to Crosnier 1997 a, 1997b) along the midline, two closely set tubercles anterior to it on mesogastric region.

Branchial regions with two converging radial rows of four blunt tubercles each, the external one sinuous and meeting base of lateral spine. A mesial additional row of three less-marked tubercles present between median row and mesial branchial row, with anterior tubercle being rather well-developed and others hardly discernible. Second additional row consisting of two tubercles present between two branchial rows. Each hepatic region with a row of four tubercles, increasing in size anteriorly. Two additional tubercles on each side of gastric region (anterior being smaller than posterior) and one in each anterolateral region.

Front of about the same width as orbit, depressed, trilobate, median lobe broadly triangular, pointed; lateral lobes rounded, somewhat elevated, less produced than median. Supraorbital margin parabolic, with a single fissure but some grooving in place of second fissure. Inner suborbital tooth sub-triangular, with outer margin straight and inner margin convex, separated from outer orbital margin by V-shaped hiatus opening into oblique subhepatic canal. Subhepatic region markedly granular. Anterolateral margin arched, carrying nine acuminate granular denticles with largest in middle part of arch and two to three additional granules anteriorly.

Lateral spines moderately long and stout, comprising ca 0.15 of CW, nearly straight, directed horizontally with markedly granular surface. Posterolateral margin sinuous, granular, with some granules in anterior half larger than others. Posterior margin moderately granular, trilobate: both median and lateral lobes low, triangular, similar in size. Thoracic sternum and visible parts of sterna with moderate development of even granulation, those parts of sterna within sterno-abdominal cavity smooth.

Third maxillipeds elongate; exopod bearing longitudinal fringe of hair along complete length. Endopod ischia not closing in midline, leaving a narrow triangular gap; inner margins bearing rows of rounded teeth decreasing in size distally; merus with distolateral corner forming rounded process.

Chelipeds equal in size, evenly covered with granules similar to those on carapace excepting part of lower surface of merus and inner surface of palm. Distal margin of merus bearing three laterally directed rather stout spines; distal spine largest reaching distinctly more than half length of lateral spine of carapace and ca 0.4 of maximal merus length (excluding spines); following spine reaching about half length of distal spine, and third spine being smallest. Proximally to third spine is a small spinule or sharpened tubercle. In holotype, this tubercle is more developed in left cheliped, almost indistinguishable in right one. Carpus with three tubercles on outer surface, hardly distinguishable from background granulation, anterodistal corner triangular. Upper margin of palm bearing a row of two rather blunt proximal teeth and seven subtriangular teeth. Outer surface in lower part bearing a granular ridge with three distinct elevations, proximal triangular and sharp, median and distal rounded, subequal in size. Depressions between elevations are markedly granular. Above this ridge eight granular tubercles form three indistinct longitudinal rows: lower and median ones with three, and upper with two tubercles each. Lower surface granular, lower margin with coarse granules and six to eight denticles in anterior half. Inner surface nearly smooth in upper part, sparsely granular in lower part, with angled fringe of hair along lower margin and base of fixed finger. Fixed finger slightly deflexed, cutting edge bearing a row of irregular rounded teeth in left cheliped, and a large crushing tooth in right one. Movable finger with granular outer face and typical molariform proximal process in major cheliped; inner surface with milled ridge extending for most of length and becoming less clear distally.

Ambulatory legs laterally compressed, P3 being longest (but not much longer than P2). Length to width ratio in meri varies from 3.35 in P 2 to 3.08 in P3 and 3.06 in P4. Upper surface and lower margin of meri granular, distal margin unarmed; in last pair of legs granulation extends to most of posterior face excepting lower distal corner. Upper surface of carpi with three granular carinae, median one ending in a terminal spine; distal margin with well-developed spines decreasing in size from P2 to P4. Propodi with length/width ratio comprising ca 3.7 in P2–P4, sharply keeled dorsally, in P2 and P3 keels serrated and preceded by a sparse row of granules at anterior surface of article; anterior and posterior surfaces with usual grooves. Dactyli longer than propodi, slender and slightly curved.

Abdominal terga smooth. Crest on tergite 2 of abdomen trilobate, lateral lobes rounded, median subrectangular with almost straight margin, not projecting considerably beyond laterals. Abdominal terga 3–5 fused. Penultimate segment subquadrate with sinuous lateral borders; ultimate segment (telson) forming equilateral triangle with slightly concave lateral margins. Go/1 tubular, evenly curved. Go/2 somewhat longer than Go/1, with distal part corkscrew-shaped.

Female characters and variation. Female sterna sparsely and finely granulated. Female abdomen smooth, terga separate: third tergite being broader than second and slightly broader than fourth and fifth. Genital opening covered with spheroid cap, shifted close to anterior edge of sternite, posteriorly bordered by smooth somewhat elevated cuticle, mesially bordered by subtriangular smooth area with median eminence.

Egg mass extends laterally somewhat beyond coxa of anterior ambulatory legs. Eggs small, measuring ca 0.3–0.4 mm in diameter.

The male from the Laccadive Islands is similar to the holotype, with somewhat less coarse granulation on the carapace. Only the anterior tubercle in the mesial additional row between the median and the mesial branchial row of tubercles is recognizable. The meri of P5 (missing in the holotype and the paratype) lack a distinct spine distally and are sparsely granular over most of posterior surface; carpi lack anterior carina. Length to width ratio in meri varies from 3.40 in P 2 to 3.26 in P3, 3.22 in P5, and 3.16 in P4. Propodi length/width ratio varies from 3.0 in P2, 3.72 in P3, 4 in P4 to 2.9 in P5.

Affinities

The present species is closest to Mursia australiensis Campbell, 1971 , known from Australia, New Caledonia and, until recently with some reservation, from Japan ( Campbell 1971; Galil 1993). A male specimen from Sagami Bay, Japan (Haberer coll., ZMB, unregistered), examined by us clearly belongs to that species, thus confirming the occurrence of M. australiensis in Japan.

Similarity between the two species includes general outline, carapace and cheliped granulation, and the Go/2 having a rather short and relatively stout curved terminal part. Within the genus this type of gonopod morphology is shared only by the above two species and Mursia trispinosa Parisi, 1914 (see Galil 1993, Figure 10h, i ).

Mursia minuta n. sp. can be distinguished from M. australiensis by the lobes near the lower margin of the cheliped manus forming a granular ridge with three elevations, while in M. australiensis the three lobes are widely separated and do not form a ridge-like structure. The median lobe of the crest on the second abdominal tergite is broadly subrectangular with an almost straight margin in M. minuta , while it is rounded and much narrower in M. australiensis . The Go/ 2 in M. minuta is somewhat spiralled while it is sinuous in M. australiensis .

Mursia trispinosa is distinguished from M. minuta n. sp. by the three isolated large and pointed teeth near the lower margin of the cheliped palm and the strongly denticulated lower margin of the palm. Furthermore, in M. trispinosa the posterior margin of the carapace is bilobed, and the Go/2 is crochet-shaped.

Remarks

The specimen from the Laccadives was considered erroneously a syntype of M. bicristimana Alcock and Anderson, 1894 by Galil (1993). For details see ‘‘Remarks’’ on that species.

Mursia coseli Crosnier, 1997

( Figure 13A )

Mursia coseli Crosnier 1997b, p 750 –755, Figures 1 , 2 , 3A–E , 4A .

Mursia armata: Zarenkov 1994, p 99 –102 (part: only Vitiaz stations 2603 and 2804) [not Mursia armata de Haan, 1837 ].

Material examined

Southwestern Indian Ocean : off Madagascar, RV Vitiaz, Cruise 17, St. 2603, 11 ° 069S, 48 ° 18.69E, depth 380 m, 12 November 1988: two males (one in ZMMU Ma 4858, one in IORAS, unregistered; originally identified as Mursia armata by N. A. Zarenkov, then reidentified by A. Crosnier); off Madagascar, RV Vauban, 12 ° 39.89S, 48 ° 15.29E, 375–385 m, 14 April 1971, A. Crosnier coll.: one male (holotype; MNHN B. 25584); same data as holotype: one female (paratype; MNHN B. 25585); same data as holotype, MNHN B. 24478: one male, eight females (small specimens) .

Type locality

Off Madagascar.

Type material

Holotype and 17 paratypes in the MNHN ( Crosnier 1997b).

Size

Holotype: CL 21.6 mm, CW 25.6 mm, MCW 37.3 mm . Paratype: MNHN B. 25585: CL 23.3 mm, CW 27.1 mm, MCW 34.1 . Male ZMMU Ma 4858: CL 21.5 mm, CW 25.3 , MCW 35.8 mm .

Habitat

Known from 245 to 460 m.

Distribution

Known only from off Madagascar.

Figures

Figure 1. Basal antennal segment of Calappa. (A) C. japonica, Red Sea, male, CL 13.6 mm (SMF 13592); (B) C. japonica, Gulf of Aden, male, CL 46.4 mm (ZMMU Ma 5344); (C) C. japonica, Japan, female, CL 53.5 mm (SMF 22942); (D) C. pustulosa, Strait of Mozambique, female, CL 54.6 mm (ZMMU Ma 5335).

Figure 2. Dorsal view of distal margin of cheliped merus. (A) Mursia africana, male, CL 30.4 mm (IORAS, unregistered), left cheliped; (B) M. africana, juvenile male, CL 14.7 mm (SMF 29497), left cheliped; (C) Mursia aff. danigoi, male, CL 52.5 mm (IORAS, unregistered), right cheliped; (D) Mursia bicristimana, male, CL 50.0 mm (ZMMU Ma 5353), right cheliped; (E) M. bicristimana, female, CL 37.0 mm (SMF 22942), right cheliped; (F) Mursia flamma, female, CL 46.3 mm (IORAS, unregistered), right cheliped; (G) Mursia minuta, male holotype, CL 17.1 mm (NHM 1907.5.22), right cheliped; (H) M. minuta, male, CL 19.5 mm (NHM 1898.8.26.3), right cheliped.

Figure 3. Gonopods 2 (Go/2). (A) Mursia africana, left Go/2, abdominal face, juvenile male, CL 14.7 mm (SMF 29497); (B) M. africana, left Go/2, abdominal face, CL 30.4 mm (IORAS, unregistered); (C) Mursia bicristimana, left Go/2, abdominal face, CL 50.0 mm (ZMMU Ma 5353); (D) M. bicristimana, left Go/2, terminal part, same specimen as in (C); (E) Mursia aff. danigoi, left Go/2, terminal part, abdominal face, CL 52.5 mm (IORAS, unregistered).

Figure 4. Gonopods 1 and 2 (Go/1 and 2). (A) Mursia bicristimana, left Go/1, CL 50.0 mm (ZMMU Ma 5353); (B) M. bicristimana, left Go/1, proximal part, same specimen as in (A); (C) M. bicristimana, right Go/2 inserted in Go/1, CL 48.4 mm (SMF 22942); (D) Mursia minuta, left Go/1, holotype, CL 17.1 mm (NHM 1907.5.22); (E) M. minuta, left Go/2, terminal part, same specimen as in (D); (F) M. minuta, left Go/2, same specimen as in (D).

Figure 5. Mursia bicristimana, male, Gulf of Aden, CL 48.4 mm (SMF 22942). (A) Dorsal view; (B) ventral view.

Figure 8. Merus of left last ambulatory leg, posterior view. (A) Mursia bicristimana, CL 48.4 mm, (SMF 22942); (B) Mursia aff. danigoi, CL 52.5 mm (IORAS, unregistered); (C) Mursia minuta, male, CL 19.5 mm (NHM 1898.8.26.3).

Figure 10. Mursia minuta sp. nov. (A, B) Male holotype, CL 17.1 mm (NHM 1907.5.22), dorsal and ventral views, respectively; (C, D) male from Laccadive Islands, CL 19.5 mm (NHM 1898.8.26.3), dorsal and ventral views, respectively.

Figure 11. Mursia minuta sp. nov., right cheliped. (A) Male holotype, CL 17.1 mm (NHM 1907.5.22); (B) male from Laccadive Islands, CL 19.5 mm (NHM 1898.8.26.3).

Figure 12. Mursia minuta sp. nov., female paratype, CL 16.8 mm (NHM 1934.1.16.23). (A) Female genital sternite; (B) female genital opening.

Figure 13. Cheliped palm. (A) Mursia coseli, male holotype, CL 21.6 mm (MNHN B.25584); (B) M. aff. danigoi, CL 52.5 mm (IORAS, unregistered); (C) Mursia danigoi, male paratype, 26.8 mm (MNHN B.22371).