Armatomelita tshayensis, 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 : 102-110

Armatomelita tshayensis sp. nov.

Figures 27–33 , 34 e

Diagnosis. Pereon segment 7 with central tooth and 2 small lateral denticles on each side. Pleon segments 1–3 with central tooth and 3 lateral teeth on each side, two lateral coupling in distinct procession. Urosome segment 1, mediodorsal tooth vertical, with 2 accessory teeth one in front of another on each side, all teeth directed upwards; urosome 2 with 2 pairs teeth and single cuspidate seta among them, all teeth directed upwards, medial tooth more than lateral. Telson lobes, proximal subapical notch more on outer margin. Anterior head lobe shallow, lower margin with prominent accessory process. Pereopod 1 (male) broadest distally, palm oblique; merus with two rows of short setae along all posterior margin. Pereopod 2 (male), anterior margin of dactyl rarely setose; palm oblique, convex, with strong posterodistal tooth. Maxilla 2, inner plate, facial setae row not reduced, submarginal. Uropod 3, proximal segment of outer ramus slender, with 5 clusters of marginal cuspidate setae each side.

Type material. Holotype male, 7.5 mm, X 37868 Cr 1434, Aniva Bay (Sea of Okhotsk) (46°37'16" N, 142°53'49" E, 10 m), gravel, M.G. Rogotnev & P.V. Polupanov, October 2010. Paratypes: 1 female, X 37869 Cr 1435; 18 males and females, X 37870 Cr 1436 with same data as holotype.

Type locality. Aniva Bay (Sea of Okhotsk), Far East of Russia (46°37'16" N, 142°53'49" E, 3–20 m).

Description. Male (7.5 mm). Medium size species. Vital body color dark-grey dorsal medial light strip, and with light bands on segments of limbs ( Fig. 27 a). Pereon segments 1–6 smooth dorsally, without teeth and humps; pereon segment 7 with centre tooth and 2 small lateral denticles each side ( Fig. 27 a, b, 34e). Pleon segments 1–3 with central tooth and 3 lateral teeth on each side, two lateral coupling in distinct procession. Urosome segment 1, medial-dorsal tooth vertical, with 2 accessory teeth one in front of another on each side, all teeth directed upwards; urosome 2 with 2 pairs of teeth and single cuspidate seta among them, all teeth directed upwards, medial tooth more than lateral.

Head: ( Fig. 27 a, c) slightly longer than pereonites 1 and 2 together with an indistinct rostrum; eyes medium oval, anterior head lobe shallow, inferior margin with prominent lobe; inferior antennal sinus with a short notch.

Antenna 1: ( Fig. 27 d) 80% of body length, slender; flagellum exceeding 1.5 length of peduncle, 32–33 articles, few very thin and short setae scattered along flagellum, one of two alternating articles with a specific flat simple seta; peduncle article 1 double width, but slightly shorter length to article 2, article 3 0.33 of article 2 length; accessory flagellum 5-articulate.

Antenna 2: ( Fig. 27 e) flagellum almost 1/2 times as long as peduncle, 11 articles, bundle of thin setae on each article; peduncle articles 5 slightly shorter than article 4, articles 1 + 2 + 3 shorter than article 5, articles 2 with protruding lobe almost reaching the distal end of next article, articles 3 without protruding lobe, articles 4 and 5 with 3–4 tufts of thin setae spaced along upper and down margins of the article each.

Mouthparts.

Labrum: ( Fig. 27 f) short and rounded, frontal margin slightly concave medially, densely covered by minute setae.

Mandible: ( Fig. 27 g, h) incisor crenulate and stretching in a rounded tip; raker setae stout subplumose, numerous (8+), slightly shorter then incisor; molar cylindrical triturative, chewing plate striate; palp short, slightly longer than basis from proximal margin to a tip of incisor, 3-articulate, palp segments 2 and 3 rarely setose, 1-st article with protruding lobe, the percentage of total length of the articles of the palp are 17–18% (article 1), 41– 42% (article 2), 40–41% (article 3).

Labium: ( Fig. 28 a) inner lobes small, but well defined, rounded; outer lobes rounded at distal margin.

Maxilla 1: ( Fig. 28 b, c) inner plate subtriangular, lined with a row of simple setae (9), with single plumose seta at the tip; outer plate elongate, 1.4 as long as inner plate, apically with 2 rows of 9 toothed strong setae; palp 2- articulate, article 2 2.3times as long as article 1, article 2 of left maxilla 1 apically with two rows of 11–12 cuspidate setae each, article 2 of right maxilla 1 with reduced armament, with two rows of 6–7 cuspidate setae of various length.

Maxilla 2: ( Fig. 28 d) inner plate slightly shorter than outer plate, facial row of setae of inner plate produced, not reduced, closely submarginal, tip covered with numerous simple setae; outer plate with same numerous of simple setae, but only on the tip, subapically with a rare row of 9–10 setae.

Maxilliped: ( Fig. 28 e) compact; inner plates large, fully cleft, distal margin with a row of 3 teeth, inner and distal margins with long plumose setae; outer plates reaching of 4/5 of palp article 2, inner margin lined with a row of short stout teeth-like setae longer toward the apex, smoothly into the apical row of long thin plumose setae, and with a submarginal row of weak simple setae; palp 4-articulate, the percentage of total length of the articles of the palp are 14% (article 1), 39% (article 2), 24% (article 3), 23 (article 4), article 2 with numerouse transverse rows of setae along inner margin; tip of article 3 with a row of simple setae along apical impression; article 4 inner margin with a line of serrate setae, inner surface with a dense row of tiny setae.

Pereopod 1: ( Fig. 28 f, g) coxa medium long, slightly extended and rounded distally; basis straight with a rare row of small simple setae along distal part of anterior margins and with rare long setae in the proximal half of posterior margin; ischium subrectangular with a bunch of long simple setae at the posterodistal corner; merus subrectangular, with two rows of short setae along all posterior margin, that are connected at the proximal and distal points of posterior margin, distal margin with a row of long serrate setae; carpus long, 1.4 times as long as propodus, 6–7 oblique rows of long serrate setae along outer posterior margin, 5 transverse rows of long serrate setae along anterior margin, with a row of long serrate setae along anterior and posterior parts of distal margin and tomentose at the anterior distal corner; propodus suboval, broadest medially, with 5 oblique groups of long serrate setae along outer posterior margin, with single tuft of long simple setae at the anterior margin and with a dense bunch of long simple setae at the anterior distal corner, palm oblique and minutely serrate with a row of short thin simple setae along palmar margin and with a row of cuspidate setae near the postero-distal corner; dactylus as long as palm, curved, with a row of spines along posterior margin, with nail.

Pereopod 2: ( Fig. 29 a, b) coxa rectangular, subrounded distally; basis straight, longer than coxa, with a few short and long simple setae along posterior margin and with rare short setae along anterior margin; merus subrectangular with long acute protrusion at the posterior distal corner, with two setae along posterior margin; carpus triangular, almost 3 times shorter than propodus, with 3 tufts of long setae along posterior margin; propodus subrectangular, palm oblique, convex, with weak irregular hinge tooth and with distinct acute posterodistal tooth, posterior margin with 11 tufts of serrate setae, palm with a row of small cuspidate setae; dactylus as long as oblique part of palm, curved to the inside of propodus, outer margin rarely setose, tip of dactylus obtuse rounded.

Pereopod 3: ( Fig. 29 c) coxa similar size as coxa 2, medium length, slightly narrowed distally; basis long linear with few minutely setae along anterior and posterior margins and with rare long simple setae at the proximal half of posterior margin; merus long with 2 strong cuspidate setae along anterior margin and with a cluster of 2 simple setae at the anterior distal corner, posterior margin with few simple setae; carpus 5/6 as long as merus, with 5 cuspidate setae along posterior margin; propodus linear, more narrow and slightly longer than carpus, with 5 cuspidate setae along posterior margin; dactylus small (1/3 of propodus), with nail.

Pereopod 4: ( Fig. 29 d) coxa as long as coxa 3, subquadrate, slightly broaded distally, posteriorly slightly excavated; leg is similar to that of the pereopod 3.

Pereopods 5–7 elongated from pereopod 5 to pereopod 6, pereopod 6 subequal to pereopod 7.

Pereopod 5: ( Fig. 29 e) coxa with rounded front margin and with anterior lobe pulled back and down, hind margin with rounded lower corner; basis regular, with posterior wing, slightly narrowed distally, width 0.62 as long, posterior distal corner rounded, hind margin crenulated, anterior margin with cuspidate setae; ischium subquadratic; merus broaded medially, with two cuspidate setae along posterior and anterior margins each, and with a cluster of two cuspidate setae at the posterior distal and anterior distal corners each; carpus 0.85 as long as merus, with 2 groups of 2 cuspidate setae at the anterior margin and with a single clusters of cuspidate setae at the anterior and posterior distal corners each; propodus linear, more narrow and 1.4 times as long as carpus; dactylus small (1/4 of propodus), with nail.

Pereopod 6: ( Fig. 29 f) coxa with quadrate hind margin and with anterior lobe pulled back and down; basis regular, with posterior wing, narrowed distally, width 0.58 as long, posterior distal corner rectangular, hind margin crenulated, anterior margin with cuspidate setae; ischium subquadratic; merus long, with 3 cuspidate setae along anterior and posterior margins each, and with single clusters of 3–4 strong cuspidate setae at anterior and posterior distal corners each; carpus as long as merus, with 2 groups of 2 cuspidate setae at the anterior margin and with a single clusters of cuspidate setae at the anterior and posterior distal corners each; propodus linear, more narrow and 1.3 times as long as carpus; dactylus small (1/4 of propodus), with nail.

Pereopod 7: ( Fig. 29 g) coxa small, without distinct anterior lobe and with rounded posterior lobe; basis regular, with posterior wing, narrowed distally, width 2/3 as long, posterior distal corner rectangular, hind margin crenulated, anterior margin with cuspidate setae; ischium subquadratic; merus long, with 2 cuspidate setae along anterior margin and with 3 cuspidate setae along posterior margin, and with single clusters of 4–5 strong cuspidate setae at anterior and posterior distal corners each; carpus slightly shorter than merus, with 2 groups of 2 cuspidate setae at the anterior margin, with a single group of 2 small cuspidate setae at the posterior margin and with a single clusters of cuspidate setae at the anterior and posterior distal corners each; propodus linear, more narrow and 1.4 times as long as carpus; dactylus small (1/4 of propodus), with nail.

Coxal gills 2–6. Coxal gill 6 distinctly smaller than gill 5.

Epimeral plates: ( Fig. 30 a, b, c) plates 1 and 2, hind corners squarish, minutely acuminate, both plates with oblique crest, lower margin of epimeral plate 2 convex with two small cuspidate setae; pleon plate 3, hind corner medially produced, acute, lower margin not serrate with 4 small cuspidate setae.

Pleopods: ( Fig. 30 d, e, f) normal, no sexual dimorphism; peduncle with single specific toothed coupling spine and with single cuspidate setae on the inner corner; coupling basis of inner ramus with 3 specific stout two-pointed plumose setae along inner margin.

Uropod 1: ( Fig. 30 g) peduncle with strong and curved interramal spur; rami subequal in length, shorter than peduncle length; peduncle and rami with tiny simple setae along outer edge, both rami with few tiny simple setae at tip.

Uropod 2: ( Fig. 30 h) peduncle shorter than outer ramus (0.71 ramus length); inner ramus shorter than outer, both with numerous simple cuspidate setae along outer margin; uropod 2 shorter than uropod 1.

Uropod 3: ( Fig. 30 i) peduncle subequal to peduncle of uropod 2, with two cuspidate simple setae at the posterior margin, with a single cuspidate seta at the anterior margin subapically and with a crown of simple cuspidate setae at the apex; elongate 2-articulate outer ramus (7 length of inner ramus), with 5 tufts of small cuspidate setae along anterior margin, and with 5 tufts of more long cuspidate setae along posterior margin of article 1, article 2 minutely, 5 times longer than crowning short cuspidate setae, 1/9 as long as article 1; inner ramous short and ovoid with two cuspidate setae subapically.

Telson: ( Fig. 30 j) fully cleft; lobes rather stout, diverging distally; proximal notch positioned laterally; apical and subapical simple cuspidate setae long, lobes with 2 short cuspidate setae at the medial margin each. Female (9.2 mm). Vital body color dark-grey dorsal medial light strip, and with light bands on the segments of the limbs ( Fig. 31 a). Dorsal armament as in male ( Fig. 31 a).

Head: similar to that in male.

Antenna 1: ( Fig. 31 b) slender; flagellum exceeding 1.1 length of peduncle, 29–30 articles, few very thin and short setae scattered along flagellum; peduncle article 1 double width but slightly shorter length to article 2, article 3 0.37 of article 2 length; accessory flagellum 4-articulate.

Antenna 2: ( Fig. 31 c) flagellum almost 0.42 times as long as peduncle, 8 articles, bundle of thin setae on each article; peduncle articles 5 slightly shorter than article 4, articles 1 + 2 + 3 shorter than article 5, articles 2 with protruding lobe almost reaching the distal end of next article, articles 3 with small protruding lobe, articles 4 and 5 with numerous tufts of thin setae spaced along upper and down margins of the article each.

Mouthparts: similar to those in male.

Maxilliped: ( Fig. 31 d) compact; inner plates large, fully cleft, distal margin with a row of 3 teeth, inner and distal margins with long plumose setae; outer plates short, reaching 2/3 of palp article 2, inner margin lined with a row of short stout teeth-like setae longer toward the apex, smoothly into the apical row of long thin plumose setae, and with a submarginal row of weak simple setae; palp 4-articulate, as in male, the percentage of total length of the articles of the palp are 12% (article 1), 39% (article 2), 25% (article 3), 24 (article 4).

Pereopod 1: ( Fig. 31 e, f) coxa long rectangular, rounded distally; leg as in male.

Pereopod 2: ( Fig. 32 a, b) with sexual dimorphism; coxa long rectangular, slightly narrowed and rounded distally; basis straight, slightly shorter than coxa, with a few long simple setae along distal part of posterior margin and with numerous short setae along anterior margin; merus subrectangular with long acute protrusion at the posterior distal corner, with 5 tufts long setae along posterior margin; carpus broadened distally, long triangular, 1.2 times shorter than propodus, posterior lobe slightly produced with 8 tufts of serrate setae; propodus long subrectangular, palm oblique, convex, with small posterodistal tooth, posterior margin with numerous tufts of serrate setae, palm with small cuspidate setae, and with a dense cluster of serrate setae near posterodistal tooth; dactylus as long as oblique part of palm, slightly curved to the inside of propodus, inner margin with a rare row of short simple setae, outer margin with few setae, tip of dactylus with acute nail.

Pereopods 3 and 4: ( Fig. 32 c, d): coxal plates longer than as in male, legs similar to as in male.

Pereopods 5–7 ( Fig. 32 e–h): coxal plates more high than in male, legs as in male.

Coxal gills 2–6 ( Fig. 32 a, c–f) large, oval. Coxal gill 6 slightly distinctly smaller than gills 2–5.

Epimeral plates: ( Fig. 33 a, b, c) plates 1 and 2, hind corners squarish, minutely acuminate, both plates with oblique crest, lower margin of epimeral plate 2 convex with 5 small cuspidate setae; pleon plate 3, hind corner medially produced, acute, lower margin not serrate with 8 small cuspidate setae.

Pleopods ( Fig. 33 d–g): normal; peduncle of pleopods 1 and 2 with two specific toothed setae on the inner corner each, peduncle of pleopod 3 with single specific toothed coupling spine and with single cuspidate setae on the inner corner; inner ramus slightly longer than outer, basis of inner ramus with 5 (pleopod 1) or 4 (pleopods 2 and 3) specific stout two-pointed plumose setae along inner margin.

Uropod 1: ( Fig. 33 h) peduncle with strong and curved interramal spur; inner ramus subequal to outer, subequal to peduncle length; peduncle and rami with numerous tiny simple setae along outer edge, both rami with few cuspidate setae at tip.

Uropod 2: ( Fig. 33 i) peduncle shorter than outer ramus (0.58 ramus length); inner ramus shorter than outer, with numerous tiny simple cuspidate setae along outer margin both; uropod 2 shorter than uropod 1.

Uropod 3: ( Fig. 33 j) peduncle subequal to peduncle of uropod 2, with one cuspidate seta at the 2/3 of anterior margin, with a row of simple cuspidate setae at the apex; elongate 2-articulate outer ramus (7 length of inner ramus), with 5 tufts of cuspidate setae along anterior and posterior margins of article 1 each, article 2 minutely, 5 times longer than crowning short cuspidate setae, 1/12 as long as article 1; inner ramus short and ovoid with two cuspidate setae apically.

Telson: ( Fig. 33 k) similar to that in male.

Sexual dimorphism: Coxal plates in female more longer than in male. Pereopod 2 in male bigger than in female; carpus of pereopod 2 in female more longer than in male.

Variations: In armament of epimeral plates.

Etymology. Named in honor of Janna Tzhay, the employee of Sakhalin’s Fishery Institute and my colleague in recognition of her long-term assistance in my work.

Ecology: Armatomelita tshayensis was found in the depth interval 10–20 m on the gravel-sand bottom. Females with eggs in marsupium was found in September–October.

Distribution: Only type locality. Aniva Bay, Okhotsk Sea (Sakhalin Island).

Figures

FIGURE 27. Armatomelita tshayensis sp. nov., holotype, male: a—lateral view with coloration, b—carination of abdominal segments, c—cephalon, d—antenna 1, e—antenna 2, f—upper lip; g—right mandible, h—left mandible; scale: a— 5 mm; b, d, e— 1 mm; g, h— 0.1 mm.

FIGURE 28. Armatomelita tshayensis sp. nov., holotype, male: a—low lips, b—left maxilla 1, c—pulp of right maxilla 1, dmaxilla 2, e—maxilliped, f—pereopod 1, g—dactylus and palmar margin of pereopod 1, outer side; scale: a, b, c, d, e, g— 0.1 mm; f— 1 mm.

FIGURE 29. Armatomelita tshayensis sp. nov., holotype, male: a—pereopod 2, b—dactylus and palmar margin of pereopod 2, iner side, c—pereopod 3, d—pereopod 4, e—pereopod 5, f—pereopod 6, g—peropod 7; scale: a, c, d, e, f, g— 1 mm; b— 0.1 mm.

FIGURE 30. Armatomelita tshayensis sp. nov., holotype, male: a—epimer 1, b—epimer 2, c—epimer 3, d—pleopod 2, ecoupling spines of pleopod 2, f—coupling setae of pleopod 2, g—uropod 1, h—uropod 2, i—uropod 3, j—telson; scale: a – d, g – i— 1 mm; e, f, j— 0.1 mm.

FIGURE 31. Armatomelita tshayensis sp. nov., paratype, female: a—carination of abdominal segments with coloration, bantenna, c—antennula, d—maxillipod, e—pereopod 1, f—propodus and dactylus of pereopod 1; scale: a, b, c, e— 1 mm; d, f— 0.1 mm.

FIGURE 32. Armatomelita tshayensis sp. nov., paratype, female: a—pereopod 2, b—dactylus and palmar margin of pereopod 2, c—pereopod 3, d—pereopod 4, e—pereopod 5, f—coxa 6, g—pereopod 6, h—pereopod 7; scale: a, c – h— 1 mm; b— 0.1 mm.

FIGURE 33. Armatomelita tshayensis sp. nov., paratype, female: a—epimer 1, b—epimer 2, c—epimer 3, d—pleopod 2, ecoupling spines of pleopod 2, f—coupling setae of pleopod 1, g—coupling setae of pleopod 2, h—uropod 1, i—uropod 2, juropod 3, k—telson; scale: a – d, h – k— 1 mm; e – g— 0.1 mm.

FIGURE 34. Dorsal carination of new species of genera Megamoera and Armatomelita: a— Megamoera similidentata sp. nov., holotype, male, b— Megamoera striata sp. nov., holotype, male, c— Megamoera falsomikulitschae sp. nov., paratype, female, d— Megamoera aequidentata sp. nov., holotype, female, e— Armatomelita tshayensis sp. nov., holotype, male; scale: a, b— 2 mm, c, d, e— 1 mm.