Accalathura crenulata ( Richardson, 1901 )

King, Rachael A., 2008, A re-description of Accalathura crenulata (Richardson, 1901) from type material and the description of two new Accalathura species (Crustacea: Isopoda: Cymothoida), Zootaxa 1761, pp. 17-29 : 18-20

Accalathura crenulata ( Richardson, 1901)

( Fig. 1 )

Calathura crenulata Richardson, 1901: 509 –510.—1905: 74–75, figs 58–61. Accalathura crenulata (in part) Barnard, 1925: 147 –148, pl. 4, fig. 18.

Material examined. SYNTYPE, USNM 23900, between Nassau and Andros Island, Bahamas, in Gulf weed, 38.4 m, coll. H. Richardson, 1875, 1 ovigerous female (30 mm).

Other material. USNM 189044, Caledonia Bay, Panama, 3 April 1939, 2 immature females (15 mm). USNM 273528, narrow shelf southeast of Bourge De Casse Pilote, Martinique, 49–69 m, coll. University of Miami, otter trawl, 10 July 1969, 1 immature female (19 mm).

Diagnosis. Antennae 1 and 2 similar length; antenna 1 flagellum more than 1.5 times as long as peduncle; antenna 2 flagellum as long as combined lengths of peduncular articles 3–5. Pereopod 1 propodus 2 times as long as broad (excluding ventral lobe). Pereopod 2 propodus 2.1 times as long as broad. Uropodal endopod broad and rounded, 1.5 times as long as broad, with setae concentrated apically. Telson broadest at midlength, tapered to blunt point.

Description. Female. Head, pereon and pleon without distinct pigmentation evident. Clusters of long setae present laterally on pereon at articulations of pereopods (setae missing from type specimen, setal inserts visible).

Antenna 1 and 2 similar length. Antenna 1 peduncle with articles 2 and 3 similar length, flagellum longer than peduncle, with 19 articles. Antenna 2 peduncular article 3 shortest, article 4 and 5 similar length, flagellum similar length to peduncle, with 15 articles.

Pereopod 1 merus broader than long and enclosing carpus; propodus 2 times as long as broad, with proximal ventral lobe, ventral margin between lobe and dactylus excavated, with evidence of setation along ventral margin (damage has removed all setae). Pereopod 2 basis and ischium with paired rows of long dorsal setae; merus broader than long and enclosing carpus, with long dorsal and ventral setae; carpus with long ventral setae; propodus 2.1 times as long as broad, ventral margin with six robust setae, five most proximal setae vary in lengths (middle setae largest) and possess setule at mid-length, sixth most distal seta trifid, lacking setule at mid-length. Pereopod 3 basis and ischium with paired rows of long dorsal setae; merus longer than broad and covering carpus, with long dorsal and ventral setae; carpus with long ventral setae; propodus 2.5 times as long as broad, ventral margin with seven robust setae, six most proximal setae vary in lengths (middle setae largest) and possess setule at mid-length, seventh most distal seta is split distally into four points and lacking setule at mid-length. Pereopods 4–7 becoming more elongate posteriorly, with numerous robust setae on carpus and propodus.

Pleopod 1 exopod 2.1 times as long as broad, with at least 50 distal long plumose setae; endopod shorter than exopod, 4.5 times as long as broad, with 10 distal long plumose setae. Uropodal peduncle inner distal margin blunt (not acute or raised), outer distal margin acute and slightly raised, endopod bluntly rounded, 1.5 times as long as broad, with setae concentrated apically. Uropodal exopod reaching just past peduncle of endopod, dorsal and ventral margins with long plumose and simple setae (simple setae are concentrated apically). Telson broadest at mid-length, 2 times as long as broad, tapered to blunt point, with long simple setae distally, distal 1/3 margin serrate.

Male. Unknown.

Distribution. Bahamas (type locality); Martinique; Caledonia Bay, Panama.

Remarks. There are several factors that have made this species description difficult. Only one specimen of type material exists (USNM 23900): a single ovigerous female that is currently labeled as a syntype but is, according to Richardson (1901; 1905), the specimen upon which she based her description. Due to the age and fragility of the specimen it was not dissected in this study so certain characters such as the mouthparts cannot be described. Rather than being representative of a large range of specimens, the syntype female specimen seems to be quite unlike the many other specimens examined in this study. The broad uropodal endopod and the relative lengths of the antennae (antennae 1 and 2 are of a similar length) make it distinct. Three other specimens, a female from Martinique (USNM 273528) and two immature females from Caledonia Bay, Panama (USNM 189044) could be reliably identified in this study as A. crenulata . A lack of geographic coverage within the NMNH collections, for this species in its type locality ( Bahamas), compounded the problem, as no other specimens from the type locality were available for comparison. There is also damage (loss of setae) to the type (loss of setation of the uropods and pereopods) that is likely due to the effects of preservation and the age of the specimen. Nevertheless, the diagnostic characters clearly show a distinct species that is likely to be distributed throughout the Caribbean and across into the Pacific Ocean adjacent to the Panama Canal.

Figures

FIGURE 1. Accalathura crenulata (Richardson, 1901), USNM 23900, syntype female, 30 mm (circles show setal inserts, where setae are missing). A, whole animal, dorsal view; B, pereopod 1; C, pereopod 2; D, dorsal view of telson and uropods; E, distal end of uropodal peduncle and endopod.