Dynamenella alveolata, Schotte & Kensley, 2005

Schotte, Marilyn & Kensley, Brian, 2005, New species and records of Flabellifera from the Indian Ocean (Crustacea: Peracarida: Isopoda), Journal of Natural History 39 (16), pp. 1211-1282 : 1253-1255

Dynamenella alveolata sp. nov.

( Figures 23 , 24 )

Material examined

Holotype: USNM 280296 , one male (4.0 mm), R/ V Te Vega cruise 2, sta 9-24, Pulau Nais, off Sumatra, 00 ° 419N, 97 ° 549E, coll. J. Colinvaux, 24 November 1963 . Paratypes: USNM 280297 , two ovigerous females 4.0 mm, 12 juveniles, same data as holotype .

Description

Male. Body length five times width. Integument pitted. Posterior border of pereonite 7 and pleon appearing granular. Pleon bearing two low, pitted transverse tubercles on either side of midline. Pleotelson granulose, rugose with many small, pitted tubercles over dome. Subapical foramen elliptical, directed anterodorsally, separated from apex by slit closed most of its length. Ventral margins of pleotelson outcurved to meet in midline.

Antennular peduncle, articles 1 and 2 combined slightly longer than article 1; flagellum of eight articles, extending to middle of pereonite 1. Antennal peduncle articles increasing in length from 1 to 5, flagellum with 12 articles, reaching to pereonite 3. Mouthparts typical of genus but distal molar of left mandible with broad tooth fitting into indentation in corresponding region of right mandible as in D. liochroea and D. trachydermata . Pereopod 1, two simple and one fringed setae at posterodistal margin of merus and single fringed seta each at anterodistal margins of carpus and propodus. Pereopod 2, long, prominent seta at mid-length of ischium; three long, simple and three fringed setae at posterodistal angle of merus. Pereopod 7, fringe of long setae along posterior margin of ischium; single long and four long, fringed setae at posterodistal margin of merus; six fringed, stout setae on distal margin of carpus.

Penes thickened at one-third length with setules present, tapering to acute apices. Pleopod 1, rami subequal in width and length. Pleopod 2, appendix masculina flattened basally with marginal setae, tapering to acute apex slightly more than one-fourth length beyond apex of endopod. Uropodal rami extending beyond pleotelson, broadly rounded apically with margins appearing serrate; exopods with small tubercles proximally on dorsal surface; endopods with lateral margins upcurved.

Ovigerous female. Pleon smooth; pleotelson pitted, with faint median depression, otherwise smooth. Uropodal rami small, extending only slightly beyond pleotelson. Internal pouches absent.

Remarks

Dynamenella alveolata is most similar to D. trachydermata Harrison and Holdlich, 1982 (locality Queensland, Australia). It is considerably larger, holotype males are 4.0 and 2.8 mm, respectively, while the allotype female of the new species is 4.0 mm versus 2.0 mm for the latter. In the males, the pleotelsonic foramina serve to distinguish the two; in D. alveolata it is narrowly elliptical, breadth three times depth, while in the other species it is nearly circular. The dome of the pleotelson of the new species (male) is much more rugose with small pitted tubercles scattered over its surface.

Etymology

The specific name, from the Latin for ‘‘small hollow or cavity’’, refers to the pleotelsonic foramen.

Figures

Figure 23. Dynamenella alveolata sp. nov. (A) Male in dorsal view; (B) male, lateral view; (C) frons; (D) female, pleon, lateral view; (E) antennule; (F) antenna; (G) female, pleon, posterior view; (H) male, pleon in ventral view; (I) female, pleon in ventral view; (J) female, pleon, dorsal view; (K) pleopod 1; (L) male, pleotelsonic foramen; (M) female, pleotelsonic foramen; (N) right mandible.

Figure 24. Dynamenella alveolata sp. nov. (A) Pereopod 1; (B) pleopod 3; (C) pereopod 7; (D) penes; (E) male pleopod 2; (F) pereopod 2.