Leptalpheus cf. forceps Williams, 1965

Fig. 3A, B

Leptalpheus forceps Williams 1965: 194, figs. 1, 2; Dawson 1967: 224; Saloman 1971: 67; Chace 1972: 77; (?) Christoffersen 1980: 135; Williams 1984: 101, fig. 69; Abele & Kim 1986: 194, 228-229, figs. a, b; Felder & Rodrigues 1993: 366; (?) Christoffersen 1998: 361.

Leptalpheus cf. forceps — Anker 2008: 788, figs. 4, 5, 6A, B.

Material examined. 3 ov. females (cl 3.4–3.8 mm), RMNH D54558, Panama, Caribbean coast, Bocas del Toro, Isla Bastimentos, near main village, sand flat near mangroves, yabby pump, 0–0.2 m, in burrows of Lepidophthalmus sp., leg. A. Anker, 0 3.05.2007 [fcn 07-164B]; 1 male (cl 4.8 mm), MNHN-IU-2011-5238, same collection data [fcn 07-165B]; 1 ov. female (cl 3.9 mm), OUMNH.ZC. 2011-06-022, Panama, Caribbean coast, Bocas del Toro, Isla Bastimentos, near main village, sand flat near mangroves, yabby pump, 0–0.2 m, in burrows of Lepidophthalmus sp., leg. A. Anker, J.A. Vera Caripe, J.A. Baeza, 18.11.2006 [fcn 06-597]; 1 ov. female (cl not measured), UP, same collection data [fcn 06-598].

Description. See Williams (1965) and Anker (2008).

Size. The Panamanian specimens range from 3.4 mm to 4.8 mm cl, thus being smaller than the type specimens from North Carolina (cl 5.2 mm and 7.8 mm) and the specimens from Costa Rica (cl 6.1–8.2 mm) reported by Anker (2008); the largest ovigerous female from Bocas del Toro has a cl of 3.9 mm.

Colour in life. Semitransparent with reddish or purplish chromatophores arranged in diffuse transverse bands on the abdomen; posterior abdominal somites with a greenish tinge; antennular and antennal peduncles and tail fan with some reddish or greenish chromatophores; chelipeds with some chromatophores on merus and carpus, chelae mostly colourless, hyaline-white; walking legs semitransparent; eggs bright green (Fig. 3A, B; see also colour photographs in Anker 2008).

Type locality. USA, North Carolina, Newport River.

Distribution. Western Atlantic: from North Carolina to the northern Gulf of Mexico (Williams 1965; Dawson 1967; Saloman 1971), Costa Rica, as L. cf. forceps (Anker 2008), Panama, as L. cf. forceps (present study).

Ecology. In Bocas del Toro, all specimens were collected from burrows of Lepidophthalmus cf. sinuensis Lemaitre & Rodrigues, 1991 (Fig. 3 C), on a very shallow sand flat, adjacent to a small mangrove creek and seagrass beds.

Remarks. The Panamanian specimens, although significantly smaller than the North Carolina and Costa Rican specimens, are clearly adults, as evidenced by the presence of numerous ovigerous females (Fig. 3 B). Otherwise, they are similar to the Costa Rican specimens reported as L. cf. forceps by Anker (2008). The proportions of the antennular peduncles seem to be slightly different between L. forceps from North Carolina and L. cf. forceps from Costa Rica and Panama (cf. Williams 1965, fig. 1B; Anker 2008, fig. 4A). In addition, some Costa Rican male specimens had a long caudal appendix on the uropodal endopod (Anker 2008, fig. 4J); such an appendix was not observed in the Panamanian specimens and was also lacking in specimens of L. forceps collected in the Indian River lagoon in Florida (A. Anker, pers. obs.). A more comprehensive morphological and molecular assessment of L. forceps populations throughout the known range is needed to determine if L. forceps is a single species, variable both morphologically (Anker 2008) and ecologically (being associated with Upogebia and several species of Lepidophthalmus), or a complex of several cryptic species.