Mursia bicristimana Alcock and Anderson, 1894

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 : 2859-2867

Mursia bicristimana Alcock and Anderson, 1894

( Figures 2D, E , 3C, D , 4A, B , 5A, B , 6A, B , 7A, B , 8A , 9A )

Mursia bicristimana Alcock and Anderson 1894, p 179 ; 1896, Plate 24, Figure 5 ; Alcock 1896, p 150–151; 1899, p 23–24, Plate III, Figures 3, 3a, b .

? Mursia armata bicristimana: Doflein 1904, p 41 , Plate 17, Figure 3 , Plate 18, Figure 4 .

Mursia bicristimana Lloyd 1907, p 6 ; Kemp and Sewell 1912, p 29.

? Mursia bicristimana: Galil 1993, p 356 –357 (part: specimens collected onboard RV Anton Bruun).

Mursia armata: Zarenkov 1994, p 100 –101 (part: Vitiaz St. 2560, 2573, 2825) [not Mursia armata de Haan, 1837 ].

not Mursia bicristimana: Laurie 1906, p 355 –356; Galil 1993, p 356 –357 (part: specimens from Sri Lanka and the Laccadives deposited in the NHM), Figures 1f , 3j, k , 5c, d [5 Mursia minuta sp. nov.].

Material examined

Gulf of Aden: RV Meteor Cruise 5, St. 267, 13 ° 27.59N, 47 ° 20.59E – 13 ° 27.99N, 47 ° 21.89E, depth 359–362 m, beamtrawl, M. Türkay and A. Allspach coll., 13 March 1987: three males, five females ( SMF 29499); same data: 104 juveniles ( SMF 29500); RV Ichtyandr, Haul 60, 14 ° 00.59N, 48 ° 529E, depth 250 m, commercial trawl, September 1982, A. Levin coll.: two males ( ZMMU Ma 5352). Arabian Sea: South of Socotra Is., RV Vitiaz Cruise 17, St. 2560, 12 ° 17.7– 12 ° 14.29N, 53 ° 08.9– 53 ° 05.69E, depth 375–380 m, shrimp trawl, 27 October 1988: two males ( IORAS unregistered, identified as Mursia armata by N. A. Zarenkov); Error Seamount, RV Vitiaz, Cruise 17, St. 2573, 10 ° 1997– 10 ° 16.259N, 56 ° 0793– 56 ° 07.59E, depth 408 m, shrimp trawl, 30 October 1988: one male, one female ( IORAS unregistered, identified as Mursia armata by N. A. Zarenkov); RV Vitiaz, Cruise 17, St. 2825, 10 ° 10.59– 10 ° 18.99N, 56 ° 08.89– 56 ° 06.79E, depth 395–420 m, M. V. Heptner coll.: one male, four females ( ZMMU Ma 5353), two females, one juvenile ( IORAS unregistered) .

Specimens tentatively assigned to M. bicristimana : Nicobar Islands: Deutsche Tiefsee- Expedition, RV Valdivia, St. 208, depth 296 m, 7 February 1899: one female ( ZMB 13660, identified as Mursia armata bicristimana by Doflein). Andaman Sea: International Indian Ocean Expedition, RV Anton Bruun, Cruise 1, St. 22B, 10 ° 399N, 97 ° 069E, depth 290 m, 24 March 1963: two males, one female ( USNM 309672). Philippines: Philippines Expedition, RV Albatross, St. 5403, near Capitancillo Island between Leyte and Cebu, 11 ° 109N, 124 ° 179150E, depth 333 m, 16 March 1909: one male, three females ( USNM 65407). Philippines Expedition, RV Albatross, St. 5408, Camotes Islands, NW of Pacijan Island, 10 ° 409150N, 124 ° 159E, depth 291 m, 18 March 1909: one male ( USNM 1006735).

Type locality

Gulf of Manaar, Sri Lanka. R.I.M.S.S. Investigator, St. 151 (13.5 miles north, 64 ° W of Colombo), depth 142–400 fathoms, brown mud, 4 December 1893 [according to Alcock and Anderson (1894) and Anonymous (1914)].

Type material

In the original description by Alcock and Anderson (1894) there is no mention of the number or sex of the specimens obtained at Investigator St. 151. However, since the size ( CL × MCW 521× 41 mm) is given for only one specimen without indication of further material, this might indicate that the description and original record is based on a single specimen. In this case, that specimen has to be considered a holotype. Its size indicates that it probably is the same as that illustrated by Alcock and Anderson (1896, Plate 24, Figure 5 ). If not lost or destroyed, this specimen should still be deposited in the ZSI in Calcutta, but all efforts to get any information or the specimen on loan failed. In case that there is more than one specimen in the original sample from Investigator St. 151 a lectotype should be selected.

Subsequently a large male ( CL × MCW 547.8× 88 mm) was reported from Investigator St. 204 off Colombo (06 ° 509200N, 79 ° 369200E, 180–271 fathoms, 18 April 1895) by Anderson (1896). This specimen was mentioned in Alcock’s (1896) account of the Calappidae and described and figured in great detail by Alcock (1899, p 23–24, Plate III, Figures 3, 3a, b ). This specimen, however, has no type status and most probably it is deposited in the ZSI.

A specimen in the NHM (1898.8.26.3) was considered as a syntype by Galil (1993). Examination of this specimen revealed that it is accompanied by a label carrying the following information ‘‘ Syntype? or Alcock det. 11 ° 149300N, 74 ° 579150E, 68–140 fathoms, coll. Indian Museum’’. Thus, the locality data on the label points to the Laccadive Islands, not to the Gulf of Manaar. Most probably the specimen was collected at Investigator St. 246, 15 October 1898, since the coordinates as well as the depth information given on the label agree exactly with the data for that station. It is therefore clear that the specimen was collected at a different locality and four years after the description of M. bicristimana was published, consequently this is not a syntype of that species. As will be discussed in detail below, a close examination of the specimen reveals that it belongs to a distinct and yet undescribed species.

Size

The measurements of the presumed type given by Alcock and Anderson (1894) are CL 21 mm, MCW 41 mm; those of the large male mentioned by Alcock (1896, 1899) are CL 47 mm, CW 67 mm. Adult males from the Gulf of Aden measure CL 28.1–48.2, CW 35.5– 65.8, LS 4.6–6.2 mm; the females from the same station measure CL 36.1–43.7 mm, CW 45.9–56.5 mm, LS 5.5–6.3 mm (broken in smallest specimen). The male specimen from Error Seamount ( ZMMU Ma 5353) measures CL 50.0 mm, CW 65.5 mm, LS 8.0 mm. The female from the Nicobar Islands measures CL 39.9 mm, CW 51.1, LS 9.8; the largest male from the Andaman Sea measures CL 44.2 mm, CW 59.8, LS 8.0.

Habitat

Records range from 250 to 420 m depth. Information on the sediments is scarce. In the case of Meteor 5, St. 267 it consisted of fine sand with numerous gastropod and bivalve shells (A. Allspach, personal communication). At Investigator St. 360 the sediment was probably fine sand ( Lloyd 1907) and at Investigator St. 391 it was recorded that the trawl contained a remarkable number of the gastropod Xenophora pallidula Reeve, 1842 ( Kemp and Sewell 1912).

Distribution

Gulf of Aden, Arabian Sea (off Socotra Is., Error Seamount), Laccadive Sea, Gulf of Manaar. Specimens tentatively assigned to M. bicristimana , but probably belonging to very similar but distinct species, have been recorded from the Andaman Sea and the Philippines.

Extended diagnosis (based on Alcock and Anderson and specimens from the Gulf of Aden and the Arabian Sea)

Carapace transversally oval, convex, 1.6–1.7 times broader than long (including lateral spines) and 1.25–1.35 times broader than long not counting lateral spines. Dorsal surface finely granular with one median and six radial rows of tubercles (protuberances according to Crosnier 1997 a, 1997b) and one additional tubercle in each anterolateral region. Front wider than orbit, trilobate, median lobe broadly triangular, projecting well beyond rounded lateral lobes. Supraorbital margin unifissured. Inner suborbital tooth subtriangular with external edge straight or slightly convex, separated from outer orbital margin by U-shaped hiatus opening into oblique subhepatic canal. Anterolateral margin arched, with 11 acuminate granular denticles decreasing in size posteriorly. Lateral spines of moderate length, measuring from about one-tenth of CW in adult specimens from the Gulf of Aden to about one-third of CW in small juveniles, directed horizontally and slightly anterolaterally. Posterior margin with lateral lobes sharply triangular, median lobe small to indistinct.

Merus of cheliped bispinose, distal spine shorter than lateral spine of carapace. Upper margin of palm bearing a row of seven triangular teeth increasing in size up to sixth, last tooth smaller than the previous one. Outer surface bearing a continuous generally smooth ridge above lower margin with low sharp tooth proximally and finely granulated depression in distal half. Above this ridge seven granular tubercles forming three indistinct longitudinal rows. Area between the ridge and the rows of tubercles almost smooth. Lower margin serrated, but without well-developed teeth.

Ambulatory legs laterally compressed. Length to width ratio in meri varies from 3.4 in P 2 to 3.1 in P5. Propodi with length to width ratio varying from 3.1 in P 2 to 2.5 in P5, sharply keeled dorsally.

Crest on tergite 2 of abdomen trilobate, lateral lobes rounded, median subrectangular with almost straight or slightly convex posterior border, not projecting considerably beyond laterals. Penultimate segment of male abdomen subquadrate with sinuous margins. Ultimate segment (telson) forming equilateral triangle with slightly concave lateral margins.

Go/1 elongate, curved and tapering distally towards spinulose tip. Spinules forming terminal field around opening and extending in a thickening row along mesial face. Go/2 much longer than Go/1 with hook-shaped terminal tube, tip not reaching half distance to junction with basal part; junction mesially with pair of stiff bristles.

Female genital sternite and two previous sterna partly included in sterno-abdominal cavity densely beset with minute spinules similar to those on Go/1. Genital opening covered with spheroid cap, shifted close to anterior edge of sternite, posteriorly bordered by smooth elevated thickened cuticle, mesially bordered by subtriangular smooth area with median eminence.

Size-related variation

Within the material from the Gulf of Aden and the Arabian Sea the relative length of the lateral carapace spines decreases with size. Small specimens have lateral spines of about one-third of CW, while those of adult specimens do not exceed about one-tenth of CW. The expression of the median lobe on the posterior margin of the carapace is also variable. While small, but usually well discernible in adult males, it is very indistinct in females, and in juveniles this lobe cannot be recognized at all.

Coloration

Alcock and Anderson (1894) describe the coloration of M. bicristimana as ‘‘salmon pink’’. When obtaining the second specimen, Anderson (1896, p 103) made the following notes regarding the colour in life: ‘‘upper surface of leg and carapace pale bluish white studded with orange red granules, lower surface white, inner surface of merus of cheliped deep orange’’. All specimens studied by the authors had been stored in alcohol for extended periods and their colour was pale cream with a slightly darker carapace. In some specimens an orange spot on the inner surface of the palm near the junction with the movable finger was still visible.

Affinities

Mursia bicristimana resembles M. africana , M. flamma , M. coseli , and M. danigoi in carapace morphology and tubercle pattern on the carapace, median lobe of front projecting beyond laterals, unifissured supraorbital margin, and Go/2 morphology. It is, however, distinguished from all above species by the outer surface of the palm bearing a continuous, indistinctly trilobed, mostly smooth ridge composed of three fused lobes above the lower margin. In M. africana and M. flamma all three of these lobes are widely separated. In M. coseli the lobes are separated from each other by granular depressions forming a wave-like ridge. In M. danigoi a subsidiary tubercle partly fills the gap between the proximal and the median lobe while the distal lobe is widely separated. Further distinguishing characters and their respective character states in the different species are given in Table I.

Remarks

The identity of M. bicristimana is difficult to clarify because of the inaccessibility of the type specimen (or specimens) in the ZSI. As already discussed above, the specimen from NHM certainly is not a type of M. bicristimana and, due to some considerable morphological differences such as the number of spines on the cheliped merus (four spines versus two in bicristimana ), it cannot even be considered conspecific with the specimen described and figured by Alcock and Anderson (1894, 1896). The diagnosis given by Galil (1993) and in particular the characteristic shape of the Go/2 of the specimen thus do not refer to M. bicristimana sensu Alcock and Anderson , but to a yet undescribed taxon.

Lloyd (1907) reported M. bicristimana from the western Gulf of Aden ( RIMSS Investigator St. 360, 13 ° 369N, 47 ° 329E, 130 fathoms, probably fine sand) and Kemp and Sewell (1912) mention a record from the Laccadive Sea ( RIMSS Investigator St. 391, 9 ° 149100N, 75 ° 459E, 237 fathoms). In both cases the material is probably housed in the collections of the ZSI and was not available for examination. It is, however, probable that the specimens are conspecific with the other material from the northwestern Indian Ocean and is therefore assigned to M. bicristimana .

The specimens from the Andaman Sea listed by Galil (1993) under the same species, however, do not have the characteristic Go/2 and apparently are not conspecific with the new taxon mentioned above. These specimens appear to be conspecific with a specimen from the Nicobar Islands collected by the Deutsche Tiefsee-Expedition and identified as Mursia armata bicristimana by Doflein (1904). The specimens from the Andaman Sea and the Nicobars as well as those from the Gulf of Aden and the Arabian Sea agree with M. bicristimana sensu Alcock and Anderson in most characters including the characteristic ridge above the lower margin of the palm, the morphology of the front and the posterior border. There are, however, important differences between the material from the northwestern and the eastern Indian Ocean. In specimens from the Nicobars and the Andaman Sea the carapace bears a well-developed additional tubercle between median and first radial row of tubercles ( Figure 6A ). In specimens from the Gulf of Aden, this additional tubercle is hardly visible ( Figure 5A ). The lateral spines of the carapace in adult specimens from the Andaman Sea and the Nicobars reach about 0.15–0.18 times CW, while the Gulf of Aden specimens have somewhat shorter spines reaching only about 0.10 times CW in adult specimens. Similarly, the distal spine on the cheliped merus in specimens from the Eastern Indian Ocean is between one-quarter and one-third of the length of the merus excluding the spine, while it is somewhat shorter in specimens from the Gulf of Aden reaching only about one-fifth of the merus length.

Comparing both forms with the figure in Alcock (1899), it appears that the specimens from the Gulf of Aden are more similar to the one depicted there, since the carapace is quite smooth and the merus of the cheliped is clearly bispinose. Thus, the specimens from the Gulf of Aden would be true M. bicristimana (providing, that the specimen depicted in Alcock 1899 is the same species as that described by Alcock and Anderson 1894), while those from the Andaman Sea are similar, but differ in several characters and might belong to a distinct species. Since, however, direct comparison with the type material was not possible the identity of true M. bicristimana is still not completely clarified, therefore no further taxonomic and nomenclatural actions were taken. The specimens from the Nicobars and the Andaman Sea are therefore preliminarily assigned to M. bicristimana .

Furthermore, five specimens from the USNM collected by the RV Albatross in the Philippines and identified as M. bicristimana have been examined. The specimens, ranging in CW from 20.2 to 40.6 mm, agree with M. bicristimana by possessing the characteristic ridge above the lower margin of the palm and by having a bispinose cheliped merus. They do, however, differ from M. bicristimana as described above, by having a smoother and less granular carapace, relatively longer lateral spines (0.21–0.24 times CW) and longer distal spines on the cheliped merus (one-third to almost half the length of the merus excluding the spine). Furthermore, the meri of the last pereiopods are more slender and have a less granular surface and upper margin in specimens from the Philippines than in specimens of similar size from the Gulf of Aden. For example, the largest specimen from the Philippines ( CW 40.6 mm) has a length/width ratio of 3.5 for the merus of the last pereiopod, while the same ratio in a specimen from the Gulf of Aden ( CW 34.4 mm) is only 3.2, even though the specimen is smaller and the legs of smaller specimens tend to be more slender in both forms. As for the specimens from the Andaman Sea, they are tentatively assigned to M. bicristimana for the time being although they may represent a distinct taxon.

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 6. Mursia bicristimana, female, Nicobar Islands, CL 39.9 mm (ZMB 13660). (A) Dorsal view; (B) ventral view.

Figure 7. Cheliped palm of Mursia bicristimana. (A) Male, Gulf of Aden, CL 48.4 mm (SMF 22942); (B) female, Nicobar Islands, CL 39.9 mm (ZMB 13660).

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 9. Female genital opening. (A) Mursia bicristimana, right genital opening, CL 37.0 mm (SMF 22942); (B) Mursia flamma, right genital opening, CL 46.3 mm (IORAS, unregistered).