Cristate Pea Crab

Pinnixa cristata Rathbun, 1900

FRONTISPIECE, FIGURES 6–9

Pinnixa cristata Rathbun, 1900:589.—Fowler, 1912:596.—Hay and Shore. 1918:445, 446, pl. 36: fig. 5.—Rathbun, 1918:129, 134, fig. 78, pl. 29: figs. 8, 9.—Pearse, Humm, and Wharton, 1942:186.—MacGinitie and MacGinitie, 1949:316.—Williams, 1965:210, fig. 93 [part].—MacGinitie and MacGinitie, 1968:316.—Howard and Dörjes, 1972, fig. 11.—Dörjes, 1972:190, figs. 3, 4.—Schmitt, McCain, and Davidson. 1973:106.—Felder, 1973, pl. 10: fig. 6.—Young, 1978:183.—Williams, 1984:450,453, fig. 361 [part].—Fox and Ruppert, 1985:37, 40, 52, 115, 187, 260, 287, 300 [not pgs. 122, 129].—Abele and Kim, 1986:xvi, 64, 683, 694, 756, fig. d on p. 695.—Griffith, 1987, fig. 2E [anterior sternites].

?Pinnixia cristata.—Phillips, 1971:181 [part? questionable record, at least part are P. behreae, which see].

Pinnixa chaetopterana.—Howard and Dörjes, 1972, fig. 14 [not P. chaetopterana Stimpson, 1860].

PREVIOUS RECORDS.—ATLANTIC OCEAN. North Carolina: Beaufort (Rathbun, 1900; Hay and Shore, 1918; Rathbun, 1918; Pearse, Humm, and Wharton, 1942; Williams, 1965, 1984). South Carolina: North Inlet (Young, 1978). Edisto Island (Williams, 1965, 1984). Huntington Beach, Debidue Flat, Folly Beach, Breach Inlet, and Hunting Island (Fox and Ruppert, 1985). Georgia: Cabretta flat, Sapelo Island (Howard and Dörjes, 1972; Dörjes, 1972). Florida: Florida (Abele and Kim, 1986).

GULF OF MEXICO. Mississippi: Horn Island (Phillips, 1971) (probably specimens described as “uniformly black”; see above under account of P. behreae).

MATERIAL.—ATLANTIC OCEAN. North Carolina: Beaufort; Union College Collection; 1 female (holotype, USNM 42817). Beaufort, Fort Macon Beach; in worm tube; 6 Jul 1939; A.S. Pearse; 1 ovigerous female (USNM 155241). Beaufort, Sheepshead Shoal; in Callichirus major tube; 2 Aug 1939; 1 male, 1 ovigerous female (USNM).

South Carolina: Isle of Palms; washed on beach; 7 Jan 1936; G.R. Lunz, Jr.; 3 males, 1 female (USNM 74962). Edisto Island; from hole in beach, perhaps of annelid?; C.H. Townes; 3 males, 2 ovigerous females, 1 juvenile (USNM 74961).

Georgia: South end of Tybee Island, Chatham County; 26 Jul 1980; R.W. Heard; 6 males, 17 females (11 ovigerous), 10 juveniles (USNM). Tybee Island, 10th St. beach; from burrows of Callichirus major; 16 Apr 1988; G.A. Bishop; 11 males, 27 females (25 ovigerous) (USNM).

Florida: St. Augustine Beach; with Callichirus major; 20 Sep 1980; R.W. Heard; 12 males, 15 females (13 ovigerous) (USNM). South Melbourne Beach, Brevard County; 90 m from shore, in 2 m; 20 Jan 1980; T. Roberts; 1 male (IRCZM 089:04700). South Melbourne Beach, Brevard County; –90 m from shore, off Air Force tracking station; 6-inch (= 15 cm) PVC corer; 11 Apr 1980; K. Spring; 1 male (IRCZM 089:05113).

Fort Pierce Sites, Sebastian North: Sta. FP-84-3, 1 male, 1 female (USNM); Sta. FP-84-9, 4 males, 4 ovigerous females (USLZ 2958).

Sebastian South: Sta. FP-84-2, 1 male, 1 female (USNM).

Fort Pierce Inlet, Dynamite Point: Sta. FP-85-6, 1 male, 1 female (USNM).

Fort Pierce Inlet, Coon Island: Sta. FP-85-2, 7 males, 9 females (5 ovigerous)(USNM).

Fort Pierce Inlet, north side: Sta. FP-84-5,3 males, 4 females (1 ovigerous)—2 specimens taken with Callichirus major (USNM); Sta. FP-84-11,2 males (USNM).

Stuart Causeway: Sta. FP-84-7,1 ovigerous female (USNM).

St. Lucie, Indian River: Sta. FP-82-8, 2 males, 1 female (USNM); Sta. FP-83-2, 2 males, 1 ovigerous female (IRCZM 089:06323); Sta. FP-83-4,7 males, 4 females (1 ovigerous)—2 specimens taken with Callichirus major (USNM).

St. Lucie, Atlantic: Sta. FP-82-3, 8 males, 1 females (USNM); Sta. FP-82-5, 1 male, 1 female (USNM); Sta. FP-82-7,3 males (USNM); Sta. FP-83-3,2 males, 1 female—1 specimen taken with Callianassa grandimana (USNM); Sta. FP-83-6, 3 males, 5 females—1 specimen taken with Callichirus major, 1 specimen taken with Callianassa grandimana (USNM); Sta. FP-84-1, 6 males, 5 females (1 ovigerous)—2 specimens taken with Callichirus major (2 males, 4 females IRCZM 089:06324, remainder USNM); Sta. FP-84-4, 15 males, 8 females—3 specimens taken with Callichirus major, 1 specimen taken with Callianassa grandimana (2 males, 3 females, including photo vouchers, USLZ 2953, remainder USNM); Sta. FP-85-3, 21 males, 29 females (3 ovigerous), 3 juveniles (10 males, 14 females USLZ 2959, remainder USNM).

Lake Worth Inlet, Peanut Island: Sta. FP-87-8, 2 males, 3 females (1 ovigerous) (IRCZM 089:06392); Sta. FP-87-9, 2 males, 1 female (IRCZM 089:06394); Sta. FP-87-10, 3 males, 3 females (2 ovigerous) (IRCZM 089:06393).

Dade County, Key Biscayne, southeastern side of Bear Cut at marina: Sta. RBM Miami-4, sand flat exposed at low tide; yabby pump; 1 male (USNM); R.B. Manning; 23 May 1988.

GULF OF MEXICO. Mississippi: Horn Island, Sta. 2, yabby pump on sand flat, north side of island; 1–1.5 m deep; with Callichirus major; 9 Jul 1987; R.W. Heard; 6 males, 4 females (1 ovigerous) (USNM).

MEXICO. State of Tamaulipas: Village of Barra del Tordo, estuary at mouth of Rio Carrizal, 23°03′N, 97°46′W, collected using yabby pump, from grass bed burrowed by worms and thalassinids; 25 May 1982; D.L. Felder and R. Tinnin; 2 males (USNM 221633).

DIAGNOSIS.—Carapace 2.1 to 3.3 (mean 2.6, based on 143 specimens larger than cb 5.0 mm) times broader than long in adults, with high, sharp cardiac crest extending from side to side above posterior margin. Branchial regions each crossed by tuberculate ridge, mesially not extending to orbit, not angled laterally. No sharp carina present between orbits, replaced by low, tear-shaped transverse elevation on each side, sometimes tuberculate.

Chelipeds of males and females similar, those of males larger. In male, chela stout, distal margin of palm almost perpendicular, with very narrow but elongate tooth near middle, gape densely setose above tooth, lightly setose below. Fixed finger very short, deflexed, truncate, unarmed. In female, movable finger less deflexed, fixed finger slightly larger, each with triangular tooth, gape filled with setae.

Third walking leg (P-4) strongest, merus 2.4 to 2.9 times longer than high. Lower part of posterior surface of merus with short but dense coat of setae. Propodus 1.3 to 1.4 times longer than high, ventral (opposable) margin distinctly bicarinate. Dactylus usually lacking conspicuous longitudinal ridges on anterior and posterior surfaces, ridges occasionally present, most distinct distally.

Male and female abdomens of 7 free somites. First somite trapezoidal, slightly wider than second, articulation of somites 2–3 and somites 3–4 variably produced laterally, usually rounded, occasionally angular. Sixth somite with concave sides. Telson no wider than sixth somite, but longer, apex broadly rounded.

Gonopod as illustrated (Figures 8f–m, 9h–l).

SIZE.—Males, cl 1.3 to 3.6 mm, cb 2.4 to 10.1 mm; non-ovigerous females, cl 1.8 to 4.0 mm, cb 4.0 to 10.1 mm; ovigerous females, cl 2.6 to 3.6 mm, cb 6.5 to 9.7 mm; juveniles, cl 1.1 to 1.7 mm, cb 2.1 to 3.2 mm.

The largest specimens examined are a male, 3.2 × 10.1 mm, and a female, 3.6 × 10.1 mm. Hay and Shore (1918) and Rathbun (1918) gave the measurements of the holotype as 4.3 × 10 mm and 4.0 × 10.5 mm, respectively. Williams (1984) reported a male 3.5 × 9.1 mm and a female 4 × 11 mm. Fox and Ruppert (1985) gave 11 mm as the size of the species.

COLOR IN LIFE.—Dorsal pattern varying between two extremes: in one, background color translucent yellow or tan, with scattering of dark grey or sometimes ivory-yellow chromatophores, dactyls and extremities of propodi on walking legs translucent to faintly whitened; in other extreme, overall pattern much darker, grey to brown or dark olive, and sometimes nearly black, often with white spot on anterior slope of branchial region about halfway between orbits and lateral border of carapace, lateral border usually marked by translucent white patch; dactyls and extremities of walking legs translucent white; white color especially evident on P-4, where propodus is dark on proximal two-thirds, white on distal third.

Williams (1984:453) noted that this species shows two distinct color patterns off North Carolina. Fox and Ruppert (1985) commented that the species has an oval dark grey carapace.

DISTRIBUTION.—Atlantic coast of the southeastern United States, from at least Beaufort, North Carolina, to Miami, Florida; northern Gulf of Mexico, from Horn Island, Mississippi; and southwestern Gulf of Mexico, from Barra del Tordo, mouth of Rio Carrizal, Tamaulipas, Mexico. Intertidal and shallow subtidal to a depth of at least 2 meters.