Amblyops kashimensis, Murano, 2012

Murano, Masaaki, 2012, The Genus Amblyops (Crustacea: Mysida: Mysidae: Erythropinae) from East Asia and Australia, with Descriptions of Ten New Species, Species Diversity 17 (1), pp. 49-85 : 59-60

Amblyops kashimensis sp. nov.

(Fig. 7)

Type specimen. H olotype: adult female (damaged, ca. 15.6 mm), NSMT-Cr 21350, Kashima Sea , central Japan (exact site unknown), 3 December 1967, depth unknown, beam trawl .

Description.A nterior margin of carapace damaged.

Eyes (Fig. 7A) plate-like without visual elements, separated from each other, extending to anterior margin of rst segment of antennular peduncle; each plate quadrangular in shape, slightly wider than long; anterior margin without distinct papilliform projection but possessing small upturned knob at about center, inner part of projection extending somewhat more anteriorly than outer part.

Antennular peduncle of female (Fig. 7A) rather robust; rst segment with anterolateral corner prolonged anteriorly and tipped with several setae; second segment short; third segment 1.2 times as long as wide, armed with 6 or 7 setae along inner margin and several setae on distomesial margin.

Antennal scale (Fig. 7A, B) long and wide, overreaching distal margin of third segment of antennular peduncle by more than half of its length, narrowing very gradually from widest part at about proximal 1/3 to rounded apex, 3.5 times as long as maximum width; lateral margin naked, slightly convex in distal half, terminating in denticle; distal suture distinct. Antennal peduncle (Fig. 7B, C) less than half as long as antennal scale, almost as long as antennular peduncle, 4-segmented; second segment connected to ventral side of third segment; third segment with single prominent seta. Antennal sympod (Fig. 7A) with stout anterolateral denticle.

Mandible, mandibular palp, maxillule, maxilla, and labrum as illustrated (Fig. 7D–G).

All thoracopodal endopods damaged or missing. ffloracopodal exopods with basal plate pointed at distolateral corner.

First abdominal somite 1.3 times longer than second; second, third, and fourth somites subequal; h somite 1.3 times longer than fourth; sixth somite 1.5 times longer than

h.

All female pleopods reduced to unsegmented single lobes.

Uropodal endopod (Fig. 7H, I) rather short, tapering distally, extending to tips of apical spines of telson, armed with single spine on inner ventral surface in statocyst region. Uropodal exopod (Fig. 7H) elongated, overreaching apex of uropodal endopod by 1/3 of its length.

Telson (Fig. 7H, J) elongated linguiform with rather narrowly rounded posterior end, 1.6 times longer than last abdominal somite, 2.3 times as long as maximum width close to base, somewhat abruptly narrowing towards slight constriction at anterior 1/4; lateral margin concave in anterior half and convex in posterior half, armed on posterior 2/3 with 47 or 48 densely arranged spines, these spines spatulate distally and almost equal in length except for several slightly shorter anterior spines and slightly longer posterior ones, apicalmost pair of spines slightly longer than penultimate ones; pair of apical median plumose setae short and feeble, emerging from dorsal surface just in front of apical margin.

Etymology.ffl e speci c name, kashimensis , is derived from the Kashima Sea, from which the specimen was collected.

Remarks.ffl e holotype is not in good condition, but the eyeplates, the antennal scale, and the telson, which well demonstrate the characteristics of species, are su ciently preserved for identi cation.

Amblyops kashimensis is characterized by a telson with 47 or 48 densely arranged spines on the posterior two-thirds of the lateral margin. ffle only two species with such a telson among the previously described species of the genus are A. aequispinus and A. ewingi (cf. respectively Birstein and Tchindonova 1958; Băcescu 1967). Amblyops kashimensis is readily distinguished from A. aequispinus by the eyeplate (no distinct papilliform projection on the anterior margin in A. kashimensis versus a prominent triangular projection in A. aequispinus ) and the posterior margin of the telson (narrowly rounded in A. kashimensis versus proportionally more widely rounded in A. aequispinus ), and from A. ewingi by the armature of the telson (spines along the posterior twothirds of the lateral margin and no short spines on the apex in A. kashimensis versus spines along the whole length of the lateral margin and a pair of short apical spines in A. ewingi ).

ffle male is unknown.