Chasmocarcinus mississippiensis Rathbun, 1931

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182: 26-27

publication ID

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

publication LSID

lsid:zoobank.org:pub:849BAB5C-464A-4B4A-A586-5742411EDC01

persistent identifier

http://treatment.plazi.org/id/F16BFB33-FFBA-FFE1-FF6A-F9C5FBFBFA89

treatment provided by

Plazi

scientific name

Chasmocarcinus mississippiensis Rathbun, 1931
status

 

Chasmocarcinus mississippiensis Rathbun, 1931 

( Figs. 4View FIGURE 4 H; 22E; 29H; 37C, D; 50F; 57C; 66A ‒C; 85B; 89H)

Chasmocarcinus mississippiensis Rathbun, 1931: 72  [type localilty: Gulf of Mexico].— Dawson 1966: 177, table 1 [Gulf of Mexico].— Franks et al. 1972: 64 [Gulf of Mexico].— Felder 1973: 70, pl. 10, fig. 2 [in list].— Powers 1977: 112.— Felder & Rabalais 1986: 554, figs. 5, 6 [Gulf of Mexico].— Blow & Bailey 1992: 176 [in list].—Coelho & Coelho 1998: 813 [in list].—Felder et al. 2009: 1081 [in list].— Thoma et al. 2009: 558, 559 [Gulf of Mexico].

Chasmocarcinus mississipiensis  [sic]— Serène 1964a: 258 [in list].—Ng et al. 2008: 76 [in list].

Type material. Holotype male (8.3 × 10.4 mm) ( USNM 64074View Materials); Mississippi, Mississippi Sound near Horn I., 3.7– 9 m, 0 5.04.1931. 

Other material examined. Gulf of Mexico. 7 males  , 2 males (5.2 × 6.6 mm, 7.2 × 8.8 mm), 3 females (USNM 101082), Sabine Pass, Texas, W.G. Hewat coll., 06.1957.—1 male (8.2 × 11.0 mm), 1 female (9.2 × 12.5 mm) ( USNM 72846View Materials), Mississippi Sound near Horn I.  , Mississippi, Allen & Daily coll., 04.1931.—1 female (9.6 × 12.4 mm) (USNM 150090), Mississippi Sound off west end of Horn I.  , Mississippi, Hermes  , 20‒30 ft., 20.04.1973.— 3 males  , 3 females ( USNM 102364View Materials), 2 miles NW Fort Massachusetts, Ship I.  , Mississippi, D. Moore coll., 03.07.1956.—1 ovigerous female (7.3 × 9.6 mm) (USNM 102363), Dog Keys Pass off Horn I., 6–7.7 m, D. Moore coll., 20.06.1957.—1 male (5.7 × 6.8 mm) (USNM 104735), near Rockport, Texas, T. Hefferman coll., no date— 1 male (6.8 × 5.7 mm) ( ZRC 2013.1419View Materials), northwestern Gulf of Mexico, oil platform survey, stn Post BECO, 1986.  1 female (8.2 × 6.1 mm) ( ZRC 2013.1420View Materials), northwestern Gulf of Mexico, oil platform survey, stn Post BEAV, 1986. 

Diagnosis. Carapace ( Fig. 4View FIGURE 4 H; Felder & Rabalais 1986: fig. 5a –c) with raised, granular ridge along anterolateral margins. Epistome ( Fig. 22View FIGURE 22 E) with semicircular median lobe with median fissure, lateral margins straight ( Felder & Rabalais 1986: fig. 5c). Orbits ( Fig. 22View FIGURE 22 E) long, proportionally long eye peduncles. Antennular articles relatively short ( Fig. 22View FIGURE 22 E). Third maxilliped ( Fig. 29View FIGURE 29 H) merus broadly ovate; ischium quadrate, as long as merus. Bulging pterygostomial region, clearly visible from dorsal view. Ambulatory legs ( Fig. 4View FIGURE 4 H) proportionally short, stocky, folded P5 merus only reaching middle portion of anterolateral margin; subdistal spur present on P5 dactylus ( Fig. 66View FIGURE 66 C). Fingers of major chela ( Fig. 37View FIGURE 37 C, D; Felder & Rabalais 1986: fig. 6d, e) of large males proportionally short, only slightly longer than propodus in dorsal view; pollex as long as dactylus in large males. Fingers of minor  chela ( Fig. 37View FIGURE 37 D; Felder & Rabalais 1986: fig. 6c) scissor-like; with small, sharp teeth. Anterior margin of ventral surface of propodus, proximal portion of pollex of major chela of large males smooth, without tufts of long setae. Inner margin of cheliped carpus smooth but tooth sometimes present ( Felder & Rabalais 1986). Fused thoracic sternites 1, 2 ( Fig. 50View FIGURE 50 F) broadly triangular, proportionally wide, short. Male pleon ( Figs. 50View FIGURE 50 F, 57C) with proportionally long, narrow telson. G1 ( Fig. 66View FIGURE 66 A) stout, distal part thickened in large individuals, distal segment straight with spinules. G2 ( Fig. 66View FIGURE 66 B; Felder & Rabalais 1986: fig. 6h) about 4/5 G1 length, straight, slender, distal segment long, curved. Female pleon ( Fig. 85View FIGURE 85 B) with lateral margins of somites strongly convex; telson proportionally short. Sterno-pleonal cavity of female ( Fig. 89View FIGURE 89 H) moderately shallow, vulvae close together.

Remarks. Diagnostic to C. mississippiensis  is a conspicuous raised, granular ridge along the anterolateral margins of the carapace ( Figs. 4View FIGURE 4 H, 22E; Felder & Rabalais 1986: fig. 5a, c) and the maxilliped 3 merus is broadly ovate and the ischium quadrate ( Fig. 29View FIGURE 29 H). The distal part of the G1 is characteristically thickened in large individuals. The subdistal spur on the P5 dactylus lies flat against the distal part of the dactylus.

Felder & Rabalais (1986: 560) listed several characters that are useful in distinguishing C. mississippiensis  from C. chacei  , both of which are often found sympatrically in the Gulf of Mexico. They also pointed out that the characteristic granular anterolateral ridge and a “granulate tooth or lobe” on the inner angle of the cheliped carpus of C. mississippiensis  are also found in the two eastern Pacific species, C. latipes  and C. longipes  , which is also present in the third eastern Pacific species, C. gemmatus  n. sp.

Distribution. Gulf of Mexico. Depth: less than 10–100 m (Felder et al. 2009).

USNM

Smithsonian Institution, National Museum of Natural History

ZRC

Zoological Reference Collection, National University of Singapore

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Chasmocarcinidae

Genus

Chasmocarcinus

Loc

Chasmocarcinus mississippiensis Rathbun, 1931

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

Chasmocarcinus mississippiensis

Thoma 2009: 558
Blow 1992: 176
Felder 1986: 554
Powers 1977: 112
Felder 1973: 70
Franks 1972: 64
Dawson 1966: 177
Rathbun 1931: 72
1966
Loc

Chasmocarcinus mississipiensis

Serene 1964: 258
1964