Belonectes Wilson & Hessler, 1981

Malyutina, Marina V. & Brandt, Angelika, 2009, Description of three new species of the deep-sea munnopsid genus Belonectes (Crustacea, Isopoda, Asellota) from the Weddell Sea, Southern Ocean, Zootaxa 2277, pp. 33-52 : 34-35

Belonectes Wilson & Hessler, 1981

Belonectes Wilson & Hessler, 1981: 415 –416; Kussakin, 2003: 121; Malyutina & Brandt, 2006: 2 –15. Type species. Belonectes parvus ( Bonnier, 1896)

Diagnosis (modified after Wilson & Hessler, 1981). Natasome elongate, streamlined, pereonites 5 and 6 fused dorsomedially with dorsolateral margins free, pereonite 5 longest laterally, venter having large posteriomedial bulge with setae, and pair of convexities on each side of middle part of pereonite 5, pereonite 7 separated, subequal to pereonite 6 in lateral length, venter with narrow rounded ridge. Posterolateral margin of pleotelson angled ventrally in lateral view. Rostrum large, quadrate, constituting largest part of dorsal surface of head with distinct lateral margins, frons low. Antennular article 1 without distomedial lobe, article 3 shorter than article 2; labrum longer than clypeus; mandibular molar cylindrical, elongate, longer than condyle, palp length subequal to mandibular body length; maxilliped epipod elongate, length subequal to basis length, without angled lateral projection, tip pointed; medial lobe of palp article 4 longer and broader than article 5. Female pleopod 2 conical; male pleopod 1 navicular, with deep keel, distal lobes subequal in size; pleopod 2 protopod semicircular, stylet length about half protopod length, exopod narrow. Distal plumose setae of pleopod 3 endopod less than half length of endopod; exopod about 0.3 times as wide as and slightly longer than endopod, distal seta small. Uropod elongate, endopod about twice as long as protopod, exopod tiny, shorter than protopod.

Remarks. A distinct ventral bump on the posterior part of pereonite 5 and a large labrum were the characters indicated by Wilson and Hessler (1981) for unambiguous separation of Belonectes from its most closely related genus Disconectes . After the study of the new species we suggest some additional useful characters to distinguish Belonectes . Species of Belonectes posses the peculiar pattern of the total ventral sculpture of the natasome which includes not only the medial bulge on the pereonite 5, but also a pair of convexities on each side of the bulge, and a narrow rounded medial ridge on the pereonite 7 in front of the pleopod insertion. A medial lobe of article 4 of the maxilliped palp, which is longer and broader than article 5, can easily mark species of Belonectes : all other members of the Eurycopinae have the article 5 longer or equal to the lobe of article 4. A navicular male pleopod 1 with a deep keel is typical for all species of Belonectes .

The most useful characters to distinguish species of Belonectes are the size of the antennular article 1, the shape and size of the maxillipedal palp articles 3–5, and the shape of the distal margin of the male pleopod 1, the shape of distolateral part of the protopod of the male pleopod 2, as well as the size and shape of the preanal ridge, and the size of the uropod exopod.