Abludomelita Karaman, 1981 ( Karaman, 1981: 39 )

Labay, Vjacheslav S., 2016, Review of amphipods of the Melita group (Amphipoda: Melitidae) from the coastal waters of Sakhalin Island (Far East of Russia). III. Genera Abludomelita Karaman, 1981 and Melita Leach, 1814, Zootaxa 4156 (1), pp. 1-73 : 19-21

Genus Abludomelita Karaman, 1981 ( Karaman, 1981: 39)

Abludomelita Karaman, 1981 ( Karaman, 1981: 39) —Karaman, 1982: 246.— Notenboom, 1988: 171.— Jarret & Bousfield, 1996: 9.

Melita Stebbing, 1906: 421 (part).— Gurjanova, 1951: 750 (part).— Karaman, 1981: 41 (part).—Barnard J.L., 1969: 245 (part).— Barnard & Barnard, 1983: 664 –666 (part).

Type species. Melita gladiosa Bate, 1862: 185 .

Species. Including the new species described here, Abludomelita contains 9 species in the North Western Pacific ( Jarret & Bousfield 1996, Lowry 2015, new data): A. breviarticulata ( Ren, 2012) , A. denticulata ( Nagata, 1965) , A. huanghaiensis ( Ren, 2012) , A. japonica ( Nagata, 1965) , A. klitinii sp. nov., A. okhotensis sp. nov., A. rotundactyla ( Ren, 2012) , A. somovae ( Bulycheva, 1952) and A. unamoena ( Hirayama, 1987) ( Bulycheva 1952; Hirayama 1987; Labay 2013; Nagata 1965; Ren 2012; Tzvetkova & Kudrjaschov 1985). A. aculeata ( Chevreux, 1911) , A. amoena (Hansen, 1888) , A. gladiosa ( Bate, 1862) , A. obtusata ( Montagu, 1813) , A. proxima ( Bate, 1862) and A. richardi (Chevreux, 1900) was described only from North Atlantic (Bakir, Sezgin & Katag’an 2009; Bate 1862; Chevreux 1911; Chevreux & Fage 1925; Hansen 1888; Jarret & Bousfield 1996; Karaman 1981; Montagu 1813; Sars 1895; Stephensen 1944b).

Species incertae cedis:? A. machaera ( K.H. Barnard, 1955) from South Atlantic near Cape Town, Africa.

Diagnosis (from Jarret & Bousfield 1996, with additions). Head, anterior lobe rounded, lower margin often with small accessory processes; inferior antennal sinus narrowly notched. Antenna 1 regular, antenna 2 much shorter than antenna 1. Antenna 1, peduncular segment 3 short; accessory flagellum present. Pereon segments without dorsal teeth and denticles. Pleon segments 1–3, postero-dorsal teeth usually present. Urosome 2 with dorso-lateral pairs of teeth, each astride single simple cuspidate seta (Watling type II.A.3) ( Watling 1989).

Mouthparts regular. Upper lip rounded below. Lower lip regular, inner lobes small, well developed. Mandible, raker setae row with numerous blades (8–14); lacinia 4–5-dentate; palp segment 3 usually longer than 2; segment 1 short, with acute medial process. Maxilla 1, inner plate triangular, tip not attenuated, inner margin with numerous setae; outer plate with 9 apical tooth setae (Watling type III.1) ( Watling 1989); palp segment 1 usually with strong lateral setae or without setae. Maxilla 2, inner plate, inner face with oblique or distally submarginal row of numerous setae. Maxilliped, outer plate medium large; palp segment 2 columnar; dactylus medium.

Coxal plates 1–4 medium to shallow, 1–3 cuspate behind. Coxa 1 variously expanded distally; coxa 4 excavate behind, not deeper than in coxa 3. Pereopod 1 small, little or not sexually dimorphic; basis, antero-distal setae variously developed; merus with a cushion of short setae along posterior margin; carpus elongate ; propodus suboval, shorter than carpus. Pereopod 2 (male), carpus short, hind lobe narrow, deep, apex (margin) setose; propodus large, palm oblique, usually toothed, with distinct hinge tooth, inner face with submarginal postero-distal setae cluster, posterior margin strongly setose (3+ clusters); dactylus heavy, often shortened, broad distally or medially, outer marginal setae very weak or lacking, tip obtuse. In female, carpus relatively long but much shorter than propodus, medium deep, with broad posterior lobe; propodus relatively large (smaller than in male), usually slightly broadened distally, palm oblique; dactylus regular, outer margin smooth.

Coxa 6 (female), anterior lobe usually shallow, often subequally bifid, rarely with sexual dimorphism and with elongated anterior lobe. Pereopod 4 slightly smaller than 3. Pereopod 5, basis not grossly smaller than in 6 and 7; in all, bases regularly expanded, hind lobes normal; merus slightly broadened; dactylus typically medium short.

Pleon plates 1 and 2, hind corners squarish or acuminate, rarely produced; pleon plate 3, hind corner usually produced, acute, upper and lower margins serrate or not serrate. Uropod 1, peduncle with disto-lateral cuspidate setae; rami sublinear, with simple cuspidate setae, often shorter than peduncle. Uropod 2, inner ramus longer than peduncle, outer ramus the shorter. Uropod 3, inner ramus, apex often acute; outer ramous not elongate , terminal segment distinct.

Telson lobes regular, separated to base, each narrowing distally to acute apex, marginal cuspidate setae subapical, set in lateral and medial notches.

Coxal gills 2–5 large, 6 often distinctly smallest. Brood plates elongated or oval-elongated.

Distribution. Marine waters of boreal part of Northern hemisphere.

Remarks. Karaman (1981) resurrected Melita gladiosa Bate, 1862 as the type species of Abludomelita Karaman, 1981 , that had long been synonymized within Melita Leach, 1814 . The main features of the genus after Karaman (1981) were features of structure of maxilla 1 (“inner lobe triangular, with several distolateral setae”), maxilla 2 (inner lobe is provided with dorsal oblique row of sertae), pereopod 2 of male (“segment 6 of gnathopod 2 with distoposterior corner unproduced, dactyl normal”) and uropod 3 (2-segmented outer ramus). In the description of Karaman (1981) the genus Abludomelita included representatives of modern genera Abludomelita , Desdimelita , Megamoera , Melita , Melitoides and Quasimelita .

Jarret & Bousfield (1996) changed the diagnosis of the genus Abludomelita . It was added new main featuresthe dorsal armament of abdomen and structure of pereopod 2 of males: “Pleon segments 1–3, dorsal posterior tooth with single accessory teeth (if present); pleon 3, dorsal teeth often weak or lacking. Urosome 2 with paired dorsolateral cusps, each astride single spine”; “propod large, broadening distally, postero-distal angle produced or toothed, palm strongly toothed, hind margin with few (3–5) setal clusters; dactyl heavy, distally broad, outer marginal setae very weak or lacking”. Thus diagnostic description of the structure of pereopod 2 of males from Jarret and Bousfield (1996) is opposite to that from Karaman (1981), but corresponds to the description of the type species of Melita gladiosa .

Features of the dorsal armament of Abludomelita rotundactyla ( Ren, 2012) , A. denticulata ( Nagata, 1965) , A. klitinii sp. nov. and A. okhotensis sp. nov. indicate that this features is unstable and can not be used as a generic characteristic. With the addition of new species described here, the only stable features of the genus Abludomelita are signs of structure of maxilla 1 (inner lobe triangular, with several distolateral setae), maxilla 2 (inner lobe is provided with oblique or distally submarginal row of setae) and pereopod 2 of male (propodus large, palm oblique, usually toothed, with distinct hinge tooth, inner face with submarginal postero-distal setae cluster, posterior margin strongly setose (3+ clusters); dactylus heavy, often shortened, broad distally or medially, outer marginal setae very weak or lacking, tip obtuse).

Ren (Ren 2012) described 3 species A. breviarticulata , A. huanghaiensis and A. rotundactyla in the genus Melita . However, these species belong to the genus Abludomelita on structural features of mouthparts and pereopods 1 and 2 (gnathopods 1 and 2).

Part of species belonging to the genus Abludomelita according to the list of Lowry (Lowry 2015) excluded from Abludomelita on a set of morphological characteristics. Abludomelita tuberculata ( Nagata, 1965) returned to the genus Melita as Melita tuberculata Nagata, 1965 based on a structure of pereopod 1 and 2 of males (see below: genus Melita ).

Abludomelita mucronata ( Griffiths, 1975) has a set of characteristics which are not typical for the the genus Abludomelita : lack of central dorsal tooth on pleon segments 1, 2, and urosome segment 1 with significant development of lateral teeth, the long second segment of the outer ramus of uropod 3 (0.27 times as long as segment 1), aberrant form of the telson. So this species is put as the species incertae cedis:? Abludomelita mucronata ( Griffiths, 1975) .

Abludomelita sexstachya ( Gamo, 1977) has a set of characteristics which are not typical for the the genus Abludomelita : artricle 3 of mandibular palp with a few long setae only; inner plate of maxilla 1 weakly setose medially; inner plate of maxilla 2 with few facial setae, submarginally positioned (Gamo 1975). According to listing characteristics I include this species to the genus Quasimelita as Quasimelita sexstachya ( Gamo, 1977) .

Abludomelita semipalmata G. Karaman, 1984 excluded from the the genus Abludomelita since it refers to the fossil genus Alsacomelita G. Karaman, 1984 : Alsacomelita semipalmata G. Karaman, 1984 .

Abludomelita valida (Shoemaker, 1955) excluded from the the genus Abludomelita since it refers to the genus Melitoides Gurjanova, 1934 : Melitoides valida (Shoemaker, 1955) ( Jarret & Bousfield 1996, Labay 2014).

K.H. Barnard (1955) described from shallow waters of False Bay (Cape Town, South Africa) Melita machaera K.H. Barnard, 1955 . Lacking of descriptions of mouthparts, of structure of pereopods 3–7 and of coxa 6 of female it can not be accurately attributed this species to somebody of genera of the family. Therefore, this species with great care is refer to the genus Abludomelita , at the base of structure of pereopods 1 & 2: A. machaera ( K.H. Barnard, 1955) .