Alpheus platycheirus Boone, 1927

Alpheus platycheirus Boone, 1927 View in CoL

( Figs. 1 View Figure 1 , 2 View Figure 2 )

Alpheus platycheirus View in CoL . — Boone, 1927: 131–135, figs. 29, 30. — Bracken-Grissom and Felder, 2014: 474– 482 View Cited Treatment , figs. 15–18. — De Grave and Anker, 2017: 8.

Alpheus floridanus View in CoL . — Chace, 1972: 65 (in part, figs. 20a–f). — Christoffersen, 1979: 312. — Felder et al., 2009: 1057, 1091 (in part).

Material examined. MBUCV-XI-5543 (1 ovigerous female, CL: 7.6 mm; 1 male, CL: 10.0 mm), Venezuela, Falcón State, Paraguaná Peninsula, El Supí beach (12°00’51.2”N 69°49’59.9”W), 19 May 2013 GoogleMaps .

Diagnosis. Carapace smooth, not setose; rostrum acute, not exceeding first article of antennular peduncle; rostral carina delimited between orbital hoods, extending half of the dorsal surface of the carapace; adrostral furrows deep, reaching posteriorly to base of eyes; ocular hoods inf lated, rounded, extending beyond eye, unarmed. Cardiac notch deep.

First article of antennular peduncle w ith ventromesial carina ending in acute tooth, first article about 1.4 times as long as wide, second article about 3 times as long as wide, third article almost as wide as long. Stylocerite broad, lamellate, with acute tip, not exceeding distal margin of first article. Antenna with a robust and sharp ventrolateral tooth on basicerite; scaphocerite broad, lateral margin slightly concave, reaching distal margin of antennular peduncle.

Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for genus Alpheus . Exopod of third maxilliped long, slender, setose, not extending beyond antepenultimate article of endopod.

Major cheliped of male and female very asymmetrical in shape and unequal in size, massive and large in the male, with ischium short and unarmed (in female weakly serrated on the lateral margin); merus rectangular, with mesial surface with row of 6 teeth (only 4 in the female specimen) and scattered setae, smooth lateral surface (in female, mesiodistal portion armed with a small curved spine); carpus small and cup-shaped, with triangular projection on ventral margin; chela compressed, with abundant and scattered setae; palm without dorsal or ventral notch, 0.5 times (0.6 in female) longer than fingers; ¾ of dorsal surface of mobile finger rounded and with line of short setae, cutting edge almost straight, reaching slightly beyond fixed finger; fixed finger with almost straight cutting edge. Minor cheliped balaenicepsshaped in male (minor cheliped of female lost), with short ischium; merus subrectangular, ventral surface f lattened, with six movable spines and fringe of setae along ventromesial margin; carpus stout, cup-shaped and unarmed; chela slender, compressed, lacking depressions or grooves; fingers elongate, slender, straight, longer than palm, densely setose, with apices crossed.

Second pair of pereopods with ischium and merus elongate and subequal; carpus five-articled, first (proximal) article slightly shorter than second, second almost twice as long as third; third, fourth and fifth, subequal. Third pair of pereopods robust, ischium armed with movable spine on ventrolateral surface; merus about twice as long as carpus; propodus slightly longer than carpus, with four movable spines along ventrolateral surface, dactylus simple, subspatulate, slightly curved. Fourth pair of pereopods similar to third, propodus with five movable spines along ventrolateral surface. Fifth pair of pereopods more slender than third and fourth, ischium lacking movable spine; merus slightly longer than carpus; carpus and propodus similar in length; propodus lacking movable spines, dactylus simple, curved, narrowing to acute tip. Telson slightly tapering, longer than wide (2 times or more), with two pairs of dorsal movable spines; posterolateral margin broadly rounded, each posterolateral angle with two small movable spines, mesial larger than lateral. Uropodal exopod subequal in length to telson, lateral margin produced with subacute tooth adjacent to strong movable lateral spine; endopod broadly subovate, slightly overreaching length of exopod and telson.

Color. Body greenish, speckled with numerous light yellow and green dots, most of them isolated and not interconnecting. Carapace darker than rest of body. Major and minor chelae mesially without speckled pattern, beige or light brown; major chelae with dark spots of medium size on dorsal surface of fingers and anterior region of palm; pereopods 3–5 with diffuse reddish band on distal third of merus, and broader, less defined reddish band on carpus, more intense on extensor margin. First and second abdominal somites with minute dark dorsolateral spot ( Fig. 2 View Figure 2 ).

Remarks. The color pattern of A. platycheirus reported by Bracken-Grissom and Felder (2014) is very different from the two examples collected at the Paraguaná Peninsula, Venezuela. The material described in 2014 exhibits colors such as red, pink, brown, and orange, which differ from the specimens that we collected in Venezuela.Most likely, the shrimps from the study of Bracken-Grissom and Felder (2014) were dying or recently dead, and therefore had lost their natural pattern of coloration, as is the case with most caridean shrimp and other crustaceans.

According to the description of Bracken-Grissom and Felder (2014), the specimens found in this study coincide with the species A. platycheirus . However, in their key and description, they mention that there are 1–4 spines on the propodus of the fourth pair of pereopods, while the specimens in this study have 5 spines on the propodus. Another trait that does not match is the length and width of the first article of the antennular peduncle, which is 2 times longer than wide ( Bracken-Grissom and Felder, 2014) while about 1.4 times longer than wide in the material from Venezuela. Additionally, the second article of the antennular peduncle is 4 times as long as wide ( Bracken-Grissom and Felder, 2014), while in the specimens collected in Venezuela it is approximately 3 times as long as wide. Nevertheless, these differences are not regarded as substantial enough to indicate that the specimens correspond to another species.

Geographical distribution. Western Atlantic: Gulf of Mexico (Louisiana / Mississippi, USA?; off Veracruz, Mexico), Caribbean Sea ( Cuba, Panama, Haiti, Colombia and Guadeloupe) and Eastern Brazil (Alagoas, Espírito Santo, Rio de Janeiro, São Paulo) ( Bracken-Grissom and Felder, 2014; Bracken-Grissom et al., 2014; Almeida et al., 2018) ( Fig. 3 View Figure 3 ).

Ecology and habitat. Alpheus platycheirus inhabits muddy bottoms at depths between 12 to 122 m (Bracken-Grissom et al., 2014). However, in the Caribbean this species typically inhabits shallow depths: 21.9 m in Cuba ( Boone, 1927), from 29 to 40 m in Colombia (Bracken-Grissom et al., 2014), from 0.2 to 1.5 m in Panama ( De Grave and Anker, 2017), and between 0.17 and 0.6 m in Venezuela (this study). In Haiti, a specimen was collected from a fish stomach ( Boone, 1930); two specimens were found inside a loggerhead sponge ( Boone, 1930), a symbiotic relationship that does not appear to have been recorded since and is considered unusual (Bracken-Grissom et al., 2014). In our study, we found this species associated with Thalassia testudinum and Halodule wrightii seagrass meadows, which were established on a sandy calcareous substrate with remains of the green algae Halimeda sp. ( Mariño et al., 2018).