Desmosomatidae and Nannoniscidae (Crustacea, Isopoda, Asellota) from bathyal and abyssal depths oOE North Carolina and their evolution Author George, Robert Y. text Journal of Natural History 2001 2001-12-31 35 12 1831 1859 http://www.tandfonline.com/doi/abs/10.1080/00222930152667131 journal article 10.1080/00222930152667131 1464-5262 5275960 Mirabilicoxa hessleri n. sp. (®gure 2A±H) Material examined. Holotype male, length 2.8 mm , maximum width 1.1 mm . USNM Cat. No. 138732. Type locality . Lower Carolina slope oOE Cape Lookout, NC , Site Beta , Eastward Sta. G-12 (5808), 2700 m . Etymology . This new species is named in honour of Professor Robert R . Hessler of the Scripps Institution of Oceanography, La Jolla, CA . Diagnosis of the male. Body about four times as long as the tergal width of the ®fth pereonite. Coxal plates of the anterior four pereopods enormously produced in the copulatory male and also tipped with a seta. Coxal plate of the ®rst pereopod reaching slightly beyond the anterior margin of the cephalon. Fifth pereonite much broader than the globular and narrower fourth pereonite. Antennula composed of six articles.Uropod uniramous, about one-third the length of the pleon. Species description . Body 2.8 mm long. Cephalon about as long as the anterior two pereonites combined. Cephalon with a broad rostrum and acute anterolateral angles. First and second pereonites subequal. Third pereonite narrower than the second pereonite. Fourth pereonite distinctly globular and narrower. Fifth pereonite somewhat quadrangula r in shape, with a pronounced anterior concave margin. Sixth pereonite longer and broader than the seventh pereonite. Pleotelson with a distinct posterolateral spine, and posterior margin rounded. Antennula reaching to the ®fth peduncular article of the antenna and composed of six articles. Second article twice as long as the ®rst, more than ®ve times longer than wide. Flagellum longer than the second peduncular article, and terminal article of ¯agellum minute. Antenna less than one-half the length of the body. Article ®ve and six combined equal to the length of the ¯agellum. Proximal articles of ¯agellum with denser and longer setae. Flagellum composed of 11 articles, descending in width from proximal to distal end. First pereopod with dactylus one-half the length of propodus. Propodus about as long as carpus but narrower. Carpus with three seta-tipped spines on the inner margin, merus with a single spine at the distal inner margin, ischium less than onethird the length of basis and devoid of any marginal spine or seta. Second pereopod slightly longer than ®rst pereopod, dactylus with four seta-tipped spines on the inner margin, carpus longer than propodus and with six seta-tipped spines on the inner margin, merus one-third as long as carpus, ischium with a spine at the inner distal angle. Fourth pereopod with long setae on the inner margin of merus and carpus, ischium with a distal spine and basis stout and short. Uropod uniramous, protopod with two distal setae and endopod about four times longer than the protopod and 4.5 times longer than wide. FIG. 2. Mirabilicoxa hessleri n. sp. , Holotype male, length 2.8 mm. (A) Dorsal view. (B, C) First pereopod. (D) Second pereopod. (E) Fourth pereopod. (F) Uropod. (G) Antenna. (H) Antennula. Remarks . The copulatory male resembles the male of the northern species M. exopodata Hessler, 1970 from 3834 m (lat. 37ss59.4¾N and long. 69ss26.2¾W). However, M. hessleri diOEers from M. exopodata in having a uniramous uropod. In the latter, there is a very minute rudimentary exopod that is lacking in this new species. In addition, the posterolateral spines of the pleotelson in M. exopodata extend beyond the posteromedian margin of the pleotelson. In M. hessleri the cephalon is much larger and longer, almost the length of the anterior two pereonites combined but in M. exopodata the cephalon is slightly longer than the ®rst pereonite.