Chasmocarcinus cylindricus Rathbun, 1901

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182: 18-20

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http://doi.org/10.11646/zootaxa.4209.1.1

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scientific name

Chasmocarcinus cylindricus Rathbun, 1901
status

 

Chasmocarcinus cylindricus Rathbun, 1901 

( Figs. 3View FIGURE 3 C ‒E; 21F; 28G; 35K, L; 49F; 56E; 64A ‒F; 84D; 89D)

Chasmocarcinus typicus Rathbun, 1898a: 285  [ Trinidad] (part). Not Chasmocarcinus typicus Rathbun, 1898  . Chasmocarcinus cylindricus Rathbun, 1901: 10  , fig. 1 [type localilty: Puerto Rico]; 1918: 55 [in key], 59, figs. 28, 29.— Serène 1964a: 258 [in list].— Soto 1985: 483, 487 [Straits of Florida].— Blow & Bailey 1992: 176 [in list].— Melo 1996: 419 [in key], 420 [unnumb. fig. not C. cylindricus  ] [ Brazil]; 1998: 494 [in list].—Coelho & Coelho 1998: 813 [in list].—Ng et al. 2008: 76 [in list].—Felder et al. 2009: 1081 [in list].

? Chasmocarcinus aff. cylindricus  — Guinot et al. 2013: 279 [“South America”].

Type material. Neotype: female (4.6 × 6.1 mm) ( USNM 23765View Materials), Puerto Rico, Mayagüez Harbor, U.S. Fish Commission Porto Rico Expedition, 1898‒99, Fish Hawk , stn 6061, 22‒ 33 m  .

Other material examined. Puerto Rico. Neotype female (4.6 × 6.1 mm), 2 males (4.0 × 5.2 mm, 3.5 × 4.0 mm), 1 female (5.4 × 6.9 mm) ( USNM 23765View Materials), 2 males, 2 females ( USNM 24552View Materials), Mayagüez Harbor  , U.S. Fish Commission Porto Rico Expedition, 1898‒99, Fish Hawk , stn 6061, 22‒ 33 m, stn 135(6063), 137–139 m  ; 1 female (6.9 × 9.2 mm) (USNM 24551), stn 181(6059), 13 m; 1 male (cw 6.2 mm) ( USNM 24550View Materials), off Aguadilla, stn 167 (6055), 251 m  .— 1 male, 1 female ( USNM 67774View Materials), Johnson-Smithsonian Expedition   ; 1 male, 2 females (USNM 67775), stn 10, 18°30’24”N, 66°04’15”W, 201 m; 5 males, 5 females (USNM 67773), stn 36, 18°30’30”N, 66°23’5”W, stn 730, 18°31’30”N, 66°18’20”W, 1 female (4.0 × 4.9 mm) (USNM 67798), stn 104, 18°30’10”N, 66°13’50”W, 91 m, 08.03.1933.—1 male, 1 female (USNM 99359), La Parguera, J.A. Rivero coll., 15 m, 0 2.1955.

Guadeloupe. KARUBENTHOS 2012: 2 males (MNHN-IU-2013-9002), 3 males, 4 females (MNHN-IU-2013- 9003) [photographed], Anse à la Barque, stn GD12, 16°05.52’N, 61°46.59’W, 45 m, 09.05.2012; 1 male, 1 female (MNHN-IU-2013-9001) [photographed], Anse à la Barque, stn GD15, 16°05.39’N, 61°41.48’W, 50 m, 10.05.2012; 1 male (MNHN-IU-2013-9000), Îlot Cochon, stn GD46, 16°13.02’N, 61°32.89’W, 10 m, 20.05.2012; 15 males, 19 females (MNHN-IU-2013-13077); 1 female (MNHN-IU-2013-8998), stn GD47, 16°12.95’N, 61°33.03’W, 13 m, 20.05.2012; 10 juveniles (MNHN-IU-2013-8999), stn GD48, 16°11.21’N, 61°32.51’W, 27 m, 20.05.2012; 79 males, 93 females, 1 juvenile (MNHN-IU-2013-13078); 7 male, 9 females (MNHN-IU-2013-13076), stn GD56, 16°18.73’N, 61°32.29’W, 18 m, 20.05.2012.

Barbados. 1 male (2.3 × 2.8 mm) ( USNM 110239View Materials), 91–366 m, J.B. Lewis coll. 

Trinidad. 1 juvenile female [part of type material of C. typicus Rathbun, 1898  ] ( USNM 6901View Materials).  2 males, 1 female ( USNM 139265View Materials), Gulf of Paria, 9 m, J.M. Stanley coll., 19.01.1971. 

Jamaica. 1 male (3.6 × 4.9 mm) ( USNM 42942View Materials), Montego Bay . 

Panama. CARIB 1: 1 male (3.0 × 3.7 mm) ( USNM 1277739View Materials), 08°54.7’N, 77°41.0’W, Alpha Helix  , 30 m, 29.06.1977.GoogleMaps 

Colombia. 1 male, 1 female ( USNM 107149View Materials), Ceycen I., 29 m, R. Lemaitre et al. coll., 0 6.08.1995. 

Diagnosis. Carapace ( Fig. 3View FIGURE 3 C ‒E) proportionally wide along anterior third; conspicuous ridge of sharp granules around post-ocular, anterolateral margins of carapace. Orbits ( Fig. 21View FIGURE 21 F) long, eye peduncles short. Epistome ( Fig. 21View FIGURE 21 F, 64E, F) with semicircular median lobe with median fissure, lateral margins straight. Antennular articles relatively short ( Fig. 21View FIGURE 21 F). Third maxilliped ( Fig. 28View FIGURE 28 G) ischium quadrate, about same length as merus. Bulging pterygostomial region, clearly visible from dorsal view. Fingers of major chela of large males ( Fig. 35View FIGURE 35 K) proportionally short, only slightly longer than propodus in dorsal view; pollex as long as dactylus in large males ( Rathbun 1918: fig. 29a). Fingers of minor  chela of both sexes ( Fig. 35View FIGURE 35 L) scissor-like; with small, sharp teeth. Inner margin of cheliped carpus smooth. Ambulatory legs ( Fig. 3View FIGURE 3 C ‒E) proportionally long, folded P5 merus almost reaching anterior margin; subdistal spur present on P5 dactylus. Fused thoracic sternites 1, 2 ( Fig. 49View FIGURE 49 F) broadly triangular, proportionally wide, short. Male pleon ( Figs. 49View FIGURE 49 F, 56E) with proportionally long, narrow telson ( Rathbun 1918: fig. 29b). G1 ( Fig. 64View FIGURE 64 A ‒C) stout, distal part thickened, distal segment straight with spinules. G2 ( Fig. 64View FIGURE 64 D) about 3/4 G1 length, straight, slender, distal segment long, curved. Female pleon ( Fig. 84View FIGURE 84 D) with lateral margins of somites strongly convex; telson proportionally short. Sterno-pleonal cavity of female ( Fig. 89View FIGURE 89 D) moderately shallow, vulvae close together.

Remarks. Characteristic of the species is its carapace ( Figs. 3View FIGURE 3 C ‒E), which is proportionally wide along its anterior portion, giving it a quadrate appearance; the presence of a conspicuous ridge of sharp granules around the post-ocular and anterolateral margins of the carapace; and the proportionally long orbits and short eye peduncles ( Fig. 21View FIGURE 21 F). Also diagnostic are the third maxillipeds, which have a quadrate ischium that is about the same length as the merus.

The lot that included the holotype ( USNM 2365) originally contained four males and two females and a note by M.J. Rathbun (“largest ♂ is holotype ”) but it currently contains only two males and two females with a note (“ holotype ♂ prepared by SEM by W. Blow”). The holotype could not be found so it is presumed lost (K. Reed, personal communication). The two extant males are unfortunately incomplete, each lacking the pleons and the second specimen the two gonopods. A complete female from the same lot (4.6 × 6.1 mm, USNM 2365) is therefore selected as the neotype of Chasmocarcinus cylindricus Rathbun, 1901  .

A female from Puerto Rico (6.9 × 9.2 mm, USNM 24551) is considerably larger than the rest of the material examined. Its epistome shows some differences, with a more salient median lobe (semicircular in small individuals) and lateral lobes with slightly more elevated lower margins than in small individuals, differences that are perhaps a consequence of size. The specimen was erroneously illustrated by Rathbun (1918: fig. 28) as showing short orbits instead of the diagnostic long orbits, which were observed, together with the diagnostic ridge along the post-ocular and anterolateral margins of the carapace, in the actual specimen.

Distribution. Florida, West Indies, Panama and Colombia to Brazil (south to São Paulo state). Depth: 9–1967 m (Felder et al. 2009).

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Chasmocarcinidae

Genus

Chasmocarcinus

Loc

Chasmocarcinus cylindricus Rathbun, 1901

Ng, Peter K. L. & Castro, Peter 2016
2016
Loc

Chasmocarcinus aff. cylindricus

Guinot 2013: 279
2013
Loc

Chasmocarcinus typicus

Melo 1996: 419
Blow 1992: 176
Soto 1985: 483
Serene 1964: 258
Rathbun 1901: 10
Rathbun 1898: 285
1964