Armatomelita, Labay, Vjacheslav S., 2013

Labay, Vjacheslav S., 2013, Review of amphipods of the Melita group (Amphipoda: Melitidae) from the costal waters of Sakhalin Island (Far East of Russia). I. Genera Megamoera Bate, 1862 and Armatomelita gen. nov., Zootaxa 3700 (1), pp. 65-112 : 101

Genus Armatomelita n. gen.

Type material: Holotype: X 37868 Cr 1434. Paratypes X 37869 Cr 1435, X 37870 Cr 1436. Type locality: Aniva Bay (Sea of Okhotsk) (46° 37' 7.45" N, 142° 55' 49.56" E, 20 m).

Type species. Armatomelita tshaensis n. sp.

Diagnosis. Pereon segment 7 with medial dorsal tooth and with two accessory teeth on each side. Pleon segments 1–3 with medial dorsal tooth and with three accessory teeth on each side. Urosome segment 1, mediodorsal vertical tooth with 2 accessory teeth, one in front of another on each side. Urosome 2 with dorsolateral pairs of teeth each astride single simple cuspidate seta (Watling type II.A.3) (Watling 1989). Head, anterior lobe rounded, lower margin with small accessory processes; inferior antennal sinus narrowly notched. Antenna 1 regular, antenna 2 much shorter than antenna 1.

Mouthparts regular. Upper lip shallow notched. Lower lip regular, inner lobes well developed. Mandible, raker setae row with numerouse blades (8–10); left lacinia 6-dentate, right lacinia 5 dentate; palp segment 3 subequal 2; segment 1 short, with acute medial process. Maxilla 1, inner plate triangular, tip not attenuated, inner margin 8 setose; outer plate with 9 apical tooth setae (Watling type III.1) (Watling 1989); palp segment 1 with strong lateral setae; segment 2 moderately expanded distally. Maxilla 2, inner plate, facial setae row not reduced, submarginal. Maxilliped, outer plate medium large; palp segment 2 slightly broadened; dactylus medium.

Coxal plates 1–4 medium to shallow, 1–3 cuspate behind. Coxa 1 slightly expanded distally; coxa 4 excavate behind, not deeper than 3. Pereopod 1 small, without sexually dimorphism; basis, antero-distal setae rare; merus with two rows of short setae along all posterior margin, that are connected at the proximal and distal points of posterior margin; carpus elongate, shallow; propodus relatively narrow, shorter than carpus. Pereopod 2 (male), carpus short, hind lobe narrow, deep, apex (margin) setose; propodus large, slightly broadening distally, palm oblique convex, with distinct hinge tooth, inner face with submarginal postero-distal setae cluster, posterior margin strongly setose (11 clusters); dactylus rarely setose anteriorly, tip rounded; in female, carpus relatively long, subequal to propodus; propodus relatively large (smaller than in male), slightly narrowing distally, palm regularly convex, with postero-distal tooth.

Coxa 6 (male and female), anterior lobe shallow. Pereopod 4 subequal to 3. Pereopod 5, basis not grossly smaller than in 6 and 7; in all, bases regularly expanded, hind lobes normal; segment 4 slightly broadened; distal segments regular; dactyls typically medium short.

Pleon plates 1 and 2, hind corners squarish, minutely acuminate; pleon plate 3, hind corner medially produced, acute, lower margin not serrate. Uropod 1, peduncle with distolateral cuspidate setae; rami sublinear, with simple cuspidate setae, often shorter than peduncle. Uropod 2, rami slightly longer than peduncle, outer ramus the shorter. Uropod 3, outer ramus not elongate, terminal segment distinct. Telson lobes regular, separated almost to base, marginal cuspidate setae subapical, set in lateral and medial notches.

Coxal gills 2–5 large, 6 distinctly smallest. Brood plates suboval, large.

Relationships: This genus belongs clearly in the Melitidae s. str. because of its strongly elongated outer ramus of uropod 3 and well-developed inner lobes of labium. The strongly inaequiramous uropod 3, with the inner ramus reduced to a scale and article 2 of the outer ramous very short, combined with a normal mandible palp and the presence of dorsal teeth on the pleon, characterizes the genus as a member of the Melita group (by Jarrett & Bousfield 1996).

In the key to the Melita group by Jarrett and Bousfield (1996, p. 7) with addition of Tandberg with coauthors (2011), Armatomelita keys out together with the Abludomelita complex. It differs, however, from Desdimelita Jarret & Bousfield, 1996 , Melitoides Gurjanova, 1934 , and Quasimelita Jarret & Bousfield, 1996 by the presence of dorsal teeth on the pereosome and metasome, from Megamoera Bate, 1862 , i. a., by the presence of dorsal teeth on the pereosome and by the presence of two rows of short setae along all posterior margin of merus of pereopod 1 (in other genera only a small spot of short setae in the distal part of posterior margin of merus is observed), by the form of brood plates (oval, large, not linear and short), from Exitomelita Tandberg et al, 2011 differs by the presence of dorsal teeth on the pereosome and by a different telson, and from Abludomelita Karaman, 1981 by the presence of dorsal teeth on the pereosome and by the different proportions of pereopods 1 and 2.

Etymology: The name Armatomelita is based on the Latin word “armatus” (armed) combined with the older genus name Melita . This is because this new genus has a dorsal armament on pereon, pleon and urosome segments, in addition to its close relation to the Melita group. The name is feminine in gender.