Periclimenaeus wilsoni (Hay, 1917)

(Figs. 6, 7)

Coralliocaris wilsoni Hay 1917: 71 (type locality: United States Fish Commission Fish Hawk, 20 miles off Beaufort, North Carolina, southeastern United States).— Hay & Shore 1918: 394, Fig. 13, pl. 27, Fig. 8.

Periclimenes (Periclimenaeus) wilsoni .— Armstrong 1940: 6, Fig. 3 G.

Periclimenaeus wilsoni .— Holthuis 1951: 103, pl. 31, pl. 32, Figs. b, c.— Williams 1965: 46, Fig. 38; 1984: 82, Fig. 55.— Chace 1972: 29.— Abele & Kim 1986: 174, Figs. g–i.— Felder et al. 2009: 1055.— De Grave & Fransen 2011: 360.

Type material. Holotype: male CL 10.7 mm, POCL 6.4 mm, TL 19.4 mm, United States Fish Commission Fish Hawk, off Beaufort, North Carolina, southeastern coast of United States, [no depth data], in large sponge, 1 August 1914 (USNM 47957) . Paratypes: 2 ovigerous females, CL 6.4, 7.8 mm, POCL 4.5, 5.5 mm, TL 10.1, 12.2 mm, same station data as holotype (USNM 47961).

Non-types. FSBCI, e astern Gulf of Mexico: 1 male, CL 5.8 mm, POCL 4.0 mm, TL 12.8 mm; 2 females, CL 3.5 mm, POCL 2.6 mm, TL 8.3 mm, and CL 3.0 mm, POCL 2.2 mm, TL 7.7 mm, R/ V Hernan Cortez, 27°37’N, 83°28’W, ~ 80 km west of Egmont Key, W coast of Florida, 15 December 1970, 37 m, with small piece of host sponge (FSBCI 7589) ; 1 male, CL 8.9 mm, POCL 6.5 mm, TL 17.8 mm, R/ V Tommy Munro, 26°41’25’’N, 82°40’12’’W, station SMP 1103096, ~ 40 km west of Cayo Costa, W coast of Florida, 6 June 2011, depth 12 m, bottom trawl (FSBCI 095201) .

USNM, eastern United States Atlantic coast: 1 ovigerous female, CL 7.8 mm, POCL 5.5 mm, TL 18.7 mm, R/ V Dolphin, sta 791072, off coast of South Carolina, 33°14’54”N, 78°24’48”W, 24 m, 27 September 1979, coll. E. Wenner (USNM 186048) ; 1 ovigerous female, CL 6.9 mm, POCL 4.6 mm, TL 17.4 mm, R/V Dolphin, sta 790905, off coast of South Carolina, 32°14’12”N, 79°45’06”W, 24 m, 2 September 1979, coll. E. Wenner (USNM 186049) ; 1 male, CL 7.5 mm, POCL 4.9 mm, TL 17.2 mm, 2 ovigerous females CL 6.7, 7.3 mm, POCL 4.8, 5.2 mm, TL 17.5, 18.5 mm, Sapelo Island, Georgia, sta 175, 4– 5 miles SE of whistle buoy, 19.2 m, 8 January 1963 (USNM 181884) . — Eastern Gulf of Mexico: 1 female, CL 4.3 mm, POCL 3.2 mm, TL 11.1 mm, 2 post-ovigerous females (largest with carapace separated during capture), CL 6.8, 7.4 mm, POCL 5.2, 5.5 mm, TL 17.7, 18.7 mm, R/V Tommy Munro, station SMP 171406172, 29°42’7’’N, 84°19’36’’W, ~ 50 km east of Apalachicola, NW coast of Florida, 29 October 2014, depth 18 m, bottom trawl, USMN (1441820); 2 males, CL 8.3, 7.9 mm, POCL 5.7, 5.5 mm, TL 18.0, 19.3 mm, 10 miles SE of Alligator Point, Franklin County, Florida, [no depth data], 7 July 1952, from Ircinia sponges, coll. M.L. Wass (USNM 95589) ; 1 ovigerous female, CL 6.1 mm, POCL 3.9 mm, TL 15.5 mm, off Florida, sta 45 triangle dredge, 26°03’11”N, 82°08’27”W, 17 m, 6 December 1982, coll. Continental Shelf Associates (USNM 271103); 1 ovigerous female, CL 7.5 mm, POCL 5.2 mm, TL 19.0 mm, off Florida, sta 45 quadrat (scuba), same depth and coordinates as previous, 1 June 1983, coll. Continental Shelf Associates (USNM 271104); 1 juvenile, CL 2.8 mm, POCL 1.8 mm, TL 7.1 mm, Tortugas, Florida, sta 45–30, [no depth data], 8 August 1930, coll. W.L. Schmitt (USNM 85381); 1 ovigerous female, CL 6.7 mm, POCL 4.5 mm, TL 16.4 mm, S of Loggerhead Key, Tortugas, Florida, sta 2, red buoy, 73.1 m, 4 August 1931, coll. W.L. Schmitt (USNM 85380) ; 4 males, CL 7.9–9.2 mm, POCL 5.5–6.7 mm, TL 19.5–23.4 mm, 1 ovigerous female CL 7.8 mm, POCL 6.0 mm, TL 18.7 mm, 1 juvenile CL 5.2 mm, POCL 3.7 mm, TL 12.8 mm, S of Tortugas, Florida, 73.1 m, 4 August 1931, coll. W.L. Schmitt (USNM 85414) .

Diagnosis. Rostrum elongated, armed with 8–13 dorsal teeth in males (Figs. 6 A, 7A), or armed with 7 or 8 dorsal teeth in females (Fig. 7 F); ventral margin unarmed in both sexes; tip of rostrum in males not reaching distal margin of third antennular segment, or in females reaching only to mid-level of second antennular segment. Carapace without supraorbital spine. Antennal spine well developed. Stylocerite ending in acute tooth reaching to about mid-level of cornea. Scaphocerite reaching to about distal end of third antennular segment, lateral tooth not exceeding distal margin of lamella. Carapace anterolateral margin slightly rounded, not produced. First pair of pereopods (Fig. 6 B) symmetrical, with chela about 0.7–0.8 as long as carpus. Second pair of pereopods strongly asymmetrical in shape and size. Major cheliped massive, with row of small tubercles on lower margins of ischium and merus; chela covered with numerous small tubercles arranged mesially in honeycomb pattern, fingers curved inwards distally. Minor cheliped with row of small tubercles on lower margins of ischium and merus; dactylus cutting edge in males with rectangular tooth fitting into groove of fixed finger (Figs. 6 C–D), or in females with small rounded proximal tooth (Figs. 6 F–G). Third pereopod with ischium, merus and carpus unarmed; propodus with few small spines on ventral margin; dactylus biunguiculate. First abdominal somite in males with anterior median lobe on tergite (lobe weakly developed or absent in juveniles and non-ovigerous females). Pleura of third and fourth abdominal somites variable: in adult males each with acute anteroventral projection (Fig. 6 E); in juveniles and non-ovigerous females with or without acute projections or sometimes with obtuse projection on third pleura and rounded ventral margin of fourth pleura; in ovigerous females ventral margins of both third and fourth pleura rounded. Telson with anterior pair of dorsal spines close to distal margin of sixth abdominal somite, and posterior pair just below midlength of somite; distal margin truncate, with inner and intermediate pairs of spines similar in size.

Color. “Clear milky white; integument so transparent that color of internal organs is plainly visible; egg masses light bluish green” (Williams 1984: 83).

Distribution. Western Atlantic, southeastern United States, from North Carolina to Georgia; northern and eastern Gulf of Mexico, from Louisiana, and on Florida coast from Alligator Point east of Apalachicola Bay to Tortugas; depth: 18 to 73 m (Felder et al. 2009).

Remarks. The presence in Periclimenaeus wilsoni of an anterior median lobe on the tergite of the first abdominal somite was not mentioned in the original description by Hay (1917), or in other subsequent reports of this species by Hay & Shore (1918), Holthuis (1951), Williams (1965, 1984) and Abele & Kim (1986). Examination of the specimens reported herein obtained in recent collections, and additional specimens deposited in USNM, has shown that a median lobe on the tergite of the first abdominal somite is present also in this species, at least in adults. Thus, P. wilsoni can be included as well along with P. mcmichaeli in the P. robustus species-group. Furthermore, those same studies also did not document for P. wilsoni the presence of acute anteroventral projections on the pleura of the third and fourth abdominal somites.

The aberrant specimen depicted in Figs. 7 A–E differs notably from the typical P. wilsoni, but probably represents this species given that the two females collected in the same lot, match the description of P. wilsoni . More material from the same locality would help to discern if this is an aberrant specimen or if it may represent another, perhaps undescribed taxon.