Glypturus rabalaisae Sakai, 2011

Felder, Darryl L., 2019, Designation of a neotype for Glypturus rabalaisae Sakai, 2011, a ghost shrimp from continental shelf waters of the northern Gulf of Mexico (Crustacea: Decapoda: Callianassidae), Zootaxa 4679 (1), pp. 194-200 : 195-197

Glypturus rabalaisae Sakai, 2011

( Fig. 1 A–D)

Callianassa (Callichirus) acanthochirus .– Heard & Reames 1979: 52–53, fig. 1A–D.

Callianassa acanthochirus .— Rabalais et al. 1981: 103–105, 110–112, table 1 (part), fig. 3a–f, fig. 5A, B (part), fig. 6A–E (part).

Glypturus acanthochirus .— Sakai 1999: 73–74 (part, not Glypturus acanthochirus Stimpson, 1966 ).

Glypturus rabalaisae (nomen nudum).— Sakai 2005: 132, 133, 135, 282 (name invalid, as per Dworschak 2007: 159).

Glypturus sp. GMX-1, GMX-2.— Felder & Robles 2009: 334, 338, fig. 1, table 1.

Glypturus sp.—Felder et al. 2009: 1062, 1093; Hyžný & Müller 2012: 969, table 1, 1975.

Glypturus rabalaisae Sakai, 2011: 430–431 , 438, 546.

Neotype.― Northwestern Gulf of Mexico (Texas): female, pocl 5.9 mm ( USNM 172309 ) BLM South Texas Outer Continental Shelf study, Station 4 (replicate 3), Transect I, 28° 14’N, 96° 29’W, 10 m depth, benthic grab, 13 June 1976.

Other material. Northwestern Gulf of Mexico (Texas): 2 juvenile females ( USNM 1564605 = ULLZ 18073 ) BLM South Texas Outer Continental Shelf study, 28° 14’N, 96° 29’W, 10 m depth, bottom grab, 11 October 1976 . Northwestern Gulf of Mexico (Louisiana): 1 ovigerous female (photograph voucher), pocl 11.6 mm ( USNM 1563582 = part of ULLZ 4659 ) 28°19.088’N, 91°19.688’W, 70 m, otter trawl, 30 June 2001 ; 3 males, pocl 7.4 (photograph voucher), 6.0, 5.0 mm ( USNM 1542663 = part of ULLZ 4659 ), 28°19.088’N, 91°19.688’W, 70 m, otter trawl, 30 June 2001 ; 1 ovigerous female, pocl 14.8 mm ( USNM 1542541 = ULLZ 5466 ) off Timbalier Bay , 29° 29.303’N, 90° 24.992’W, 11.5 m, 29 July 2005 ; 1 juvenile male ( USNM 1547261 = ULLZ 13950 ) off Timbalier Bay , 12.2 m depth, 12 July 1984 ; 1 male, pocl 19.2 mm ( USNM 266213 ) bycatch of commercial shrimp trawler, off Grand Isle, November 1939 ; 1 female, pocl 7.5 mm ( USNM 1547263 = ULLZ 13952 ) BLM summer cruise, stn. S20, N500, no. 6, 1979? Northeastern Gulf of Mexico (Mississippi) : 1 male ( USNM 1564428 = ULLZ 18241 ) Mississippi Sound, 3 November 1980 .

Diagnosis. Carapace with well-defined dorsal oval, front with three spines, median spine forming rostrum reaching to or beyond middle of cornea. Eyestalk cornea darkly pigmented, inflated, disk-shaped, subterminal, not covering full width of eyestalk, not encompassing distal stalk margin. Antennal (second antenna) peduncle reaching beyond antennular (first antenna) peduncle, distal end of antennular peduncle reaching slightly beyond distal end of penultimate article of extended antennal peduncle. Major cheliped palm with 1–4 spines along dorsal margin, carpus with typically 5–8 spines along ventral margin. Minor cheliped carpus length (measured mid-height of outer surface) distinctly greater than median length of palm (measured mid-height of outer surface, extending to gape). Telson posterior margin with small median spine or triangular tooth. Pigmentation in life extensively rose-pink ( Fig. 1 ). Applicable GenBank sequence accession numbers for USNM 1542663 = ULLZ 4659: (16s) EU882932 , EU882933 ; (12s) EU875042 , EU875043 .

Size. Carapace length ranges to that of an exceptionally large male, pocl 19.2 mm, collected by a shrimp trawler off Grand Isle Louisiana. Currently limited collections otherwise include two ovigerous females, pocl 11.6 and 14.8 mm, but more commonly small individuals, pocl 5.0 to 7.5 mm, and a few even smaller juveniles.

Habitat. Infaunal burrower in fine sand, muddy sand, and sandy mud bottoms, sometimes those mixed with shell hash; offshore waters 6.5–91 m depth.

Distribution. Western Atlantic: Northeastern to northwestern Gulf of Mexico, Alabama to Texas.

Remarks. The chosen neotype for this species is a small female that was included in the “Material Examined” originally reported by Rabalais et al. (1981: 103) as Callianassa acanthochirus . Other specimens originally assigned to C. acanthochirus by those authors were illustrated in that paper (fig. 3 a–f) and were later designated as a holotype and paratypes of Glypturus rabalaisae by Sakai (2011). As these are lost, a reasonably intact topotypic specimen was chosen from among the few that remain among those listed in the 1981 report.

The reported distributional range of G. rabalaisae in both of Sakai’s accounts was limited to the type locality, but it is herewith concluded, as in Felder et al. (2009), that the report of a somewhat larger (pocl 13 mm) specimen by Heard & Reames (1979) also applies to this species, even though the line illustration in that paper does not clearly indicate presence of a posteromedian spine on the telson. Most collected specimens of G. rabalaisae are small, often immature, and apparently those readily obtainable at sediment depths reached by trawls or shallow penetrating corers and grabs. Among recent collections of this species, many were coated to varied extent by a thin layer of rust-red precipitate ( Fig. 1 ), suggesting they occupied burrows extending into redox transition zones of hypoxic sedimentary pore waters. Larger adults of the species are likely to be most common in deeper substrates, though there is no evidence that they reach the very large sizes reported for Glypturus acanthochirus and some other congeners. However, in a review of collections from the region, the largest presently known specimen of the species (USNM 266213, pocl 19.2 mm) was found to have been taken as bycatch of a Louisiana commercial shrimp trawler, 90 years ago.

G. rabalaisae is not only distinct from G. acanthochirus genetically, but also in morphology, color, and habitat. These differences are treated comparatively in “Remarks” for G. acanthochirus below.

Figures

FIGURE 1. Glypturus rabalaisae, northwestern Gulf of Mexico type materials prior to preservation. A–C, USNM 1563582 (= part of ULLZ 4659) ovigerous female, pocl 11.6 mm; D, USNM 1542663 (= part of ULLZ 4659) male, pocl 7.4 mm.