Megamoera falsomikulitschae, 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 : 86-93

Megamoera falsomikulitschae sp. nov.

Figures 14–22 , 34 c

Diagnosis. Pleon segments 1–2 with central tooth and 3 lateral denticles on each side; pleon segment 3 with central tooth and 5 denticles on each side. Urosome segment 1 with central tooth and 3 lateral denticles on each side; urosome 2 with small central tooth and 2 pairs of short teeth and single cuspidate seta among them. Telson lobes, proximal subapical notch more on inner margin. Anterior head lobe shallow, lower margin with prominent accessory process. Pereopod 1 (male) slightly broader distally, palm oblique, obtuse angled from posterior margin. Pereopod 2 (male), anterior margin of dactylus rarely setose; palm oblique, convex, with low irregular hinge tooth and small posterodistal tooth. Maxilla 1, palp segment 1 with 6 lateral setae. Maxilla 2, inner plate, facial setae reduced, submarginal in position. Uropod 3, proximal segment of outer ramus slender, with 5 clusters of marginal stout simple setae.

Type material. Holotype male, 15 mm, X 37864 Cr 1430, Aniva Bay (Sea of Okhotsk) (46°36'32.74" N, 142°55'51.47" E, 15 m). sand and gravel, M.G. Rogotnev & P.V. Polupanov, October 2010. Paratypes: 2 females, X 37865 Cr 1431; 5 males and females, X 37866 Cr 1432 with same data as holotype.

Type locality. Aniva Bay (Sea of Okhotsk) (46° 36' 32.74" N, 142° 55' 51.47" E, 10–20 m)

Description. Male (15 mm). Medium size species. Vital body color is light-brown; bases of pereopods 5–7 with an unclear picture of the diffuse bands and spots ( Fig. 14 a). Thoracic segments smooth dorsally, without teeth and humps ( Fig. 14 a, b). Pleon segments 1–2 with central tooth and 3 lateral denticles on each side; pleon segment 3 with central tooth and 5 denticles on each side. Urosome segment 1 with central tooth and 3 lateral denticles each side; urosome 2 with small central tooth and 2 pairs of short teeth and single cuspidate seta among them.

Head: ( Fig. 14 c) shorter than pereonites 1 and 2 together, with indistinct rostrum; eyes medium oval, anterior head lobe shallow, inferior margin with prominent lobe; inferior antennal sinus with short notch.

Antenna 1: ( Fig. 14 d) 70% of body length, slender; flagellum exceeding 1.5 length of peduncle, 39–40 articles, few very thin and short setae scattered along flagellum; peduncle article 1 twice as wide but shorter than length of article 2, article 3 0.3 of article 2 length; accessory flagellum 6-articulate.

Antenna 2: ( Fig. 14 e) flagellum almost 0.35 times as long as peduncle, 12–13 articles, bundle of thin setae on each article; peduncle articles 5 shorter than article 4, articles 1 + 2 + 3 shorter than article 5, articles 2 with protruding lobe reaching the middle of next article, articles 3 with short protruding lobe, articles 4 and 5 with numerous tufts of thin setae spaced evenly along the article.

Mouthparts.

Mandible: ( Fig. 15 a, b) incisor crenulate and stretching in a rounded tip; raker setae stout serrate, numerous (12+), shorter then incisor; molar cylindrical triturative, chewing plate striate; palp 3-articulate, palp segments 2 and 3 strongly setose, 1-st article with protruding lobe, the percentage of total length of the articles of the palp are 16% (article 1), 40% (article 2), 44% (article 3).

Labium: ( Fig. 15 c) inner lobes small but well defined, rounded; outer lobes semi-square at distal margin.

Maxilla 1: ( Fig. 15 d, e) inner plate subtriangular, lined with a row of plumose setae; outer plate elongate, 1.6 as long as inner plate, apically with 2 rows of 9 two-end strong setae; palp 2-articulate, article 2 2.1times as long as article 1, article 2 apically with two rows of 10 simple setae each.

Maxilla 2: ( Fig. 15 f) inner plate slightly shorter than outer plate, facial setae of inner plate reduced (9), distal, closely submarginal, tip covered with numerous simple setae; outer plate with same numerous simple setae, but only on the tip, subapically with a row of 10–12 rare setae.

Maxilliped: ( Fig. 15 g) compact; inner plates large, fully cleft, distal margin with a row of 4 teeth, inner and distal margins with long plumose setae; outer plates reaching of distal margin of palp article 2, inner margin lined with a row of short stout teethlike setae longer toward the apex, smoothly into the apical row of long thin plumose setae; palp 4-articulate, percentage of total length of the articles of the palp are 14% (article 1), 44% (article 2), 25% (article 3), 17% (article 4), article 2 with numerouse setae along distal part of inner margine; tip of article 3 bilobed, with a row of long simple setae, densely pubescent along apical impression; article 4 inner margin with a line of serrate setae (Watling type IV.1) (Watling 1989).

Pereopod 1: ( Fig. 16 a, b) coxa expanded distally with rounded corners; basis straight with a dense row of simple setae along distal half of anterior margins and more rare long setae along proximal part of posterior margin; merus subrectangular, with a cushion of short setae along distal part of posterior margin, distal margin with a row of long simple setae; carpus long, 1.4 times as long as propodus, 11 oblique rows of long serrate setae along outer posterior margin, with a row of long serrate setae along anterior and posterior parts of distal margin and tomentose at the anterior-distal corner; propodus long rectangular, with 10 groups of long serrate setae along posterior margin, with 6 tufts of various lenth simple setae 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 and rare long setae along palmar margin, obtusely angled from posterior margin; dactylus as long as palm, straight, with a row of spines along serrate posterior margin, with curved nail.

Pereopod 2: ( Fig. 16 c, d) coxa of medium length, rounded, slightly narrowed distally; basis straight, longer than coxa, with a few long simple setae along posterior margin and numerous long setae along distal half of anterior margin; merus subrectangular with short acute protrusion at the posterior distal corner; carpus triangular, 0.3 times as long as propodus; propodus subrectangular, palm oblique, convex, with low irregular hinge tooth and small posterodistal tooth, posterior margin with numerous tufts of serrate setae, palm with small simple setae, and with few tufts of long setae; dactylus as long as palm, curved to the inside of propodus, inner margin with a rare row of short simple setae, outer margin rarely setose, tip of dactylus with nail.

Pereopod 3: ( Fig. 16 e) coxa of similar size as coxa 2, suboval; basis long, linear, with few minutely setae along anterior margin and with rare long simple setae along posterior margin; merus long, with 2 cuspidate setae along anterior margin and with a single cuspidate setae at the anterior distal corner, posterior margin with few simple setae; carpus 5/6 as long as merus, with 3 bunches of cuspidate setae along posterior margin; propodus linear, slightly narrow and as long as carpus, with 3 bunches of cuspidate setae along posterior margin; dactylus medium (0.36 of propodus), with nail.

Pereopod 4: ( Fig. 16 f) coxa as long as coxa 3, width subequal to length, broadened and rounded distally, posteriorly slightly excavated; leg similar to that of pereopod 3.

Pereopods 5–7 elongated from pereopod 5 to pereopod 7.

Pereopod 5: ( Fig. 17 a) coxa with rounded frontal margin, quadrate hind margin and with anterior lobe pulled back and down; basis expanded, with posterior wing and produced down posterior distal lobe, anterior and posterior margins subparallel, width 0.62 length, posterior distal corner rounded, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadratic; merus slightly broadened medially, with two cuspidate setae along posterior margin, and with a single cuspidate seta at the posterior distal corner.

Pereopod 6: ( Fig. 17 b) coxa with quadrate hind margin and oblique front lobe, anterior part of which wit a row of tree cuspidate setae; basis slightly expanded, with posterior wing, subrounded posteriorly, width 0.55 length, posterior distal corner rectangular, rounded, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadratic; merus sublinear, long, with two single cuspidate simple setae along anterior and posterior margins each, and with single cuspidate seta at anterior and posterior distal corners each.

Pereopod 7: ( Fig. 17 c) coxa small, without distinct anterior lobe and with straight obligue posterior lobe; basis expanded, with rounded posterior wing, width 0.63 length, posterior distal corner rectangular, rounded, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadratic; merus similar to that of pereopod 6.

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

Epimeral plates: ( Fig. 17 d, e, f) plate 1 rounded triangular with 1 diagonal ridge, distal corner light obtuse, posterior margin slightly convex with 4–5 notches, lower margin with a row of 6 small cuspidate setae; plate 2, hind corner acuminate, posterior and ventral margins slightly convex, with oblique crest, posterior margin with 4 notches, ventral margin with a row of 5 small cuspidate setae; plate 3 hind corner weakly produced, acute, posterior margin concave, with 4 notches, ventral margin with a row of 8 small cuspidate setae.

Pleopods: ( Fig. 17 g–j) normal, no sexual dimorphism; peduncle with two specific toothed coupling spines on the inner corner; coupling basis of inner ramus with 4–6 of specific stout two-pointed plumose setae along inner margin.

Uropod 1: ( Fig. 18 a) peduncle with strong and curved interramal spur; rami subequal in length, slightly shorter than peduncle length; peduncle and rami with tiny simple setae along outer edge, both rami with few tiny cuspidate setae at tip.

Uropod 2: ( Fig. 18 b) peduncle shorter than outer ramus (0.74 ramus length); inner ramus shorter than outer, with numerous simple cuspidate setae along outer margin; uropod 2 shorter than uropod 1.

Uropod 3: ( Fig. 18 c) peduncle subequal to peduncle of uropod 1, with three cuspidate simple setae along posterior margin and with a crown of simple cuspidate setae at the apex; elongate 2-articulate outer ramus (9 length of inner ramous, 1.3 times as long as urosome), with 5 tufts of small cuspidate setae along anterior and posterior margin of article 1 each, article 2 minute, 2 times as long as crowning setae; inner ramus short and ovoid with one cuspidate seta subapically.

Telson: ( Fig. 18 d) fully cleft; lobes diverging distally; proximal notch positioned medially; apical and subapical simple cuspidate setae long, lobes with single short cuspidate setae at the medial margin each.

Male (11 mm). Additional description.

Labrum: ( Fig. 19 a) rounded, frontal margin slightly concave medially, densely covered by minute setae.

Pereopod 5: ( Fig. 19 b) coxa with rounded front margin, with quadrate hind margin and with anterior lobe pulled down, with 3 short cuspidate setae; basis slightly expanded, with slightly produced posterior distal lobe, anterior and posterior margins subparallel, width 3/5 of length, posterior distal corner rounded, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadrate; merus slightly broaded medially, with two long cuspidate setae at the posterior margin, and with a cluster of 2 cuspidate setae of various length at posterior and anterior distal corner each; carpus as long as merus, with few tiny 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 1.2 times as long as carpus, with 4 bunches of cuspidate setae along anterior margin; dactylus small (0.29 of propodus length), with nail.

Pereopod 6: ( Fig. 19 c) coxa with quadrate hind margin and with anterior lobe pulled down, anterior lobe with 3 short cuspidate setae; basis regular, width 0.55 length, posterior distal corner subacute, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadrate; merus sublinear, slightly expanded medially, with two cuspidate setae along anterior and posterior margins each, and with two cuspidate setae at anterior-distal and posterior-distal corners each; carpus as long as merus, with 3 bunches of cuspidate setae along anterior margin, and with single cluster of cuspidate setae at anterior-distal and posterior-distal corners each; propodus linear, more narrow and slightly longer than carpus, with 3 bunches of long cuspidate setae along anterior and posterior margins; dactylus small (0.22 of propodus), with nail.

Pereopod 7: ( Fig. 19 d) coxa small, without distinct anterior lobe and with rounded posterior lobe; basis regular, width 0.63 length, posterior distal corner subquadrate, hind margin crenulated, anterior margin with small cuspidate setae; ischium subquadratic; merus and carpus similar to that of pereopod 6; propodus linear, more narrow and 1.2 as long as carpus, with 4 bunches of cuspidate setae along anterior and posterior margins; dactylus small (0.28 of propodus), with nail.

Female (10 mm). Thoracic segments smooth dorsally, without teeth and humps ( Fig. 34 c). Pleon segments 1 with central tooth and three lateral denticles on each side; pleon segment 2 with central tooth and three lateral denticles on each side; pleon segment 3 with central tooth and 5 lateral denticles on each side. Urosome segment 1 with central tooth and 3 lateral teeth on each side; urosome 2 with central tooth and with 2 pairs of teeth and single cuspidate seta among them.

Head: similar to that of male.

Antenna 1: ( Fig. 20 a) slender; flagellum exceeding 1.6 length of peduncle, 33 articles, few very thin and short setae scattered along flagellum; peduncle article 1 double width but slightly shorter than article 2, article 3 0.32 of article 2 length; accessory flagellum 4-articulate.

Antenna 2: ( Fig. 20 b) similar to that in male.

Mouthparts: ( Figs. 20 c–i, 21a) similar to those in male.

Pereopod 1: ( Fig. 21 b, c) without sexual dimorphism, similar to that in male.

Pereopod 2: ( Fig. 21 d) with sexual dimorphism; coxa rounded subrectangular, slightly narrowed distally; basis straight, longer than coxa, with a few long simple setae along posterior margin and with rare long setae along distal part of anterior margin; merus subrectangular with short acute protrusion at the posterior distal corner; carpus broadened distally, 0.63 times as long as propodus, posterior lobe slightly produced with 6 tufts of serrate setae; propodus with subparallel anterior and posterior margins, palm oblique, convex, with small posterodistal tooth, posterior margin with 9 tufts of serrate setae, palm with small simple setae, and with a dense cluster of serrate setae near posterodistal tooth; dactylus as long as oblique part of palm, curved to the inside of propodus, inner margin with a rare row of short simple setae, outer margin rarely setose, tip of dactylus with acute nail.

Pereopods 3 and 4: ( Fig. 21 e, f) similar to those in male.

Pereopods 5–7 elongated from pereopod 5 to pereopod 6, pereopod 6 subequal in length to pereopod 7; similar to those in male ( Fig. 22 a–c).

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

Epimeral plates: ( Fig. 22 d, e, f) plate 1 rounded triangular with 1 diagonal ridge, distal corner light obtuse, posterior margin slightly convex with 4 notches, lower margin with a row of 5 small cuspidate setae; plate 2, hind corner acuminate, posterior and ventral margins slightly convex, with oblique crest, posterior margin with 4 notches, ventral margin with a row of 5 small cuspidate setae; plate 3 hind corner weakly produced, acute, posterior margin concave, with 2 notches, ventral margin with a row of 7–8 small cuspidate setae.

Pleopods: ( Fig. 22 g–k) normal, no sexual dimorphism; inner ramous sglightly longer than inner; peduncle with two specific toothed coupling spines on the inner corner; coupling basis of inner ramus with 4–5 of specific stout two-pointed plumose setae along inner margin.

Uropod 1: ( Fig. 22 l) peduncle with strong and curved interramal spur; rami subequal in length, slightly shorter than peduncle length; peduncle and rami with tiny simple setae along outer edge, both rami with few tiny cuspidate setae at tip.

Uropod 2: ( Fig. 22 m) peduncle shorter than outer ramus (0.76 ramus length); inner ramous shorter than outer, with 4–5 simple cuspidate setae along outer margin; uropod 2 shorter than uropod 1.

Telson: ( Fig. 22 n) as in male.

Sexual dimorphism: Only in structure of pereopod 2. Pereopod 2 in male bigger than in female.

Etymology. Species name falsomikulitschae refers the morphological similarity to M. mikulitschae .

Ecology: M. falsomikulitschae was found in the depth interval 5–20 m on the silt-sand and silt-gravel bottom. Females with eggs in marsupial were founded in Sepember–October.

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

Remarks. Megamoera falsomikulitschae sp. nov. is most similar to M. mikulitschae (Gurjanova, 1985) by dorsal sculpture of pleons 1–3. Although the dorsal armament of pleon segments 1–3 are more similar between M. falsomikulitschae and M. mikulitschae , the presence of three lateral dorsal teeth each side of urosome segment 1, the presence of the central tooth of urosome segment 2 and the shape of telson M. falsomikulitschae distinguishes these species.

Figures

FIGURE 14. Megamoera falsomikulitschae sp. nov., holotype, male: a—lateral view with partial coloration, b—carination of abdominal segments, c—cephalon, d—antenna 1, e—antenna 2; scale: a, b— 5 mm; d, e— 1 mm.

FIGURE 15. Megamoera falsomikulitschae sp. nov., holotype, male: a—right mandible, b—left mandible, c—lower lips, dleft maxilla 1, e—pulp of right maxilla 1, f—maxilla 2, g—maxilliped; scale: a – c— 1 mm; d – g— 0.1 mm.

FIGURE 16. Megamoera falsomikulitschae sp. nov., holotype, male: a—pereopod 1, b—dactylus and palmar margin of pereopod 1, c—pereopod 2, d—dactylus and palmar margin of pereopod 2, e—pereopod 3, f—pereopod 4; scale: a, c – f— 1 mm; d— 0.1 mm.

FIGURE 17. Megamoera falsomikulitschae sp. nov., holotype, male: a—pereopod 5, b—pereopod 6, c—pereopod 7, depimer 1, e—epimer 2, f—epimer 3; g—pleopod 3, h—coupling spines of pleopod 3, i, j—coupling setae of pleopods 2, 3; scale: a – g— 1 mm; h – j— 0.1 mm.

FIGURE 18. Megamoera falsomikulitschae sp. nov., holotype, male: a—uropod 1, b—uropod 2, c—uropod 3, d—telson; scale: 1 mm.

FIGURE 19. Megamoera falsomikulitschae sp. nov., paratype, male: a—upper lip; b—pereopod 5, c—pereopod 6, dpereopod 7; scale— 1 mm.

FIGURE 20. Megamoera falsomikulitschae sp. nov., paratype, female: a – antenna 1, b—antenna 2, c—upper lip; d—right mandible, e—left mandible without palp, f—lower lips, g—left maxilla 1, h—pulp of right maxilla 1, i—maxilla 2; scale: a, b— 1 mm; c – i— 0.1 mm.

FIGURE 21. Megamoera falsomikulitschae sp. nov., paratype, female: a—maxilliped, b—pereopod 1, c—dactylus and palmar margin of pereopod 1, d—pereopod 2, e—pereopod 3, f—pereopod 4; scale: a, c— 0.1 mm, b, d – f— 1 mm.

FIGURE 22. Megamoera falsomikulitschae sp. nov., paratype, female: a—pereopod 5, b—pereopod 6, c—pereopod 7, depimer 1, e—epimer 2, f—epimer 3, g—pleopod 1, h—coupling spines of pleopod 2, i – k—coupling setae of pleopods 1 – 3, luropod 1, m—uropod 2, n—telson; scale: a – g, l, m— 1 mm; h – k, n— 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.