Prochelator sarsi, George, 2001

George, Robert Y., 2001, Desmosomatidae and Nannoniscidae (Crustacea, Isopoda, Asellota) from bathyal and abyssal depths oOE North Carolina and their evolution, Journal of Natural History 35 (12), pp. 1831-1859 : 1841-1842

Prochelator sarsi n. sp.

(®gure 5A±K)

Material examined. Holotype female, length 2.6 mm, width 1.1 mm. USNM Cat. No. 138731.

Type locality. Western edge of Hatteras abyssal plain. Site Omega Eastward Sta. G-30 (5474).

Etymology. This species is named in honour of the renowned 19th century Norwegian carcinologist Georg Ossian Sars.

Diagnosis of female. Body 2.6 mm long, ®ve times as long as the tergal width of the ®fth pereonite. First pereonite 1.5 times longer than the second pereonite. Fifth pereonite with anterolateral angles rounded, not acute. Pleotelson longer than wide and posterolateral spines lacking. Coxal plates of anterior four pereonites not produced. Carpus of ®rst pereopod with a stout, claw-like spine and two accessory setae on inner distal margin. Propodus with a fringe of setae on inner margin. Uropod biramous.

Description. Cephalon slightly longer than ®rst pereonite. First pereonite 1.8 times longer than second pereonite. Fourth pereonite narrower than third pereonite and tapering gradually posteriorly. Fifth pereonite squarish, about as long as wide, with a concave lateral margin. Sixth and seventh pereonites subequal in length. Pleotelson elliptical in shape, broader anteriorly and posterolateral spines lacking.

Antennula slightly longer than cephalon, composed of ®ve articles, ®rst peduncular article about as long as broad; second article elongated, shorter than the ¯agellum of three articles.

Coxae of anterior four pereopods rounded, not prominent and not produced. First pereopod with dactylus one-third the length of propodus; propodus three times longer than wide, almost same length as carpus. Carpus nearly twice as long as wide, outer margin with single distal seta and inner margin with accessory seta at the base of the claw-like stout distal spine. Merus with two distal setae and ischium lacking any seta or spine. Basis three times as long as wide, with distal seta.

Second pereopod with slender articles, dactylus less than one-half the length of propodus. Propodus slightly shorter and narrower than carpus; lacking any large setae on the inner margin but provided with a row of six minute setae. Carpus with four large seta-tipped spines on the inner margin. Merus short, with two distal setae. Ischium with one distal seta. Basis three times longer than wide, with distal setae.

Third pereopod with slender articles, carpus bearing two rows of long setae. Fourth pereopod with narrow dactylus, carpus with six long setae. Seventh pereopod with slender articles, carpus with two long setae, propodus with setae on inner and outer margin.

Uropod biramous, protopod slightly longer than the exopod, distal part broader. Exopod about one-third as long as endopod. Both exopod and endopod bearing a very long apical seta.

Remarks. This new species is related to P. abyssalis Hessler, 1970 from Gay Head± Bermuda transect oOE Woods Hole in the relative proportion of the ®rst and second pereonites, a similar ®rst pereopod morphology and the squarish shape of the ®fth pereonite. Both species possess the enormously long apical setae at the tip of the exopod and endopod of the uropods. However, there is signi®cant diOEerence in the second pereopod setation patterns. Furthermore, the pleotelson in P. abyssalis has posterolateral spines but in P. sarsi the posterolateral spines are lacking.