Diasynurella khalabensis Palatov et Marin, 2023

Palatov, Dmitry M. & Marin, Ivan N., 2023, Diversity of the Caucasian genus Diasynurella Behning, 1940 (Amphipoda: Crangonyctidae) with description of four new species, Arthropoda Selecta 32 (1), pp. 23-55 : 45-52

Diasynurella khalabensis Palatov et Marin sp.n.

Figs 16–19 , 20 c–h .

MATERIAL EXAMINED. Holotype $ (bl. 4.5 mm), ZMMU Mb-1253, Lesser Caucasus, Armenia, Lori region, Khalab Ridge , 40°48′4.11″N, 44°43′35.74″E, about 2400 m a.s.l.., hand net sampling, 29 August 2011, coll. D. Palatov. Paratypes 2$$ (bl. 4.0 mm), ZMMU Mb-1254, same locality and data as for holotype .

Additional material: 3$$, LEMMI, same locality and data as for holotype .

ETYMOLOGY. The species is named after the Khalab Ridge located in the Lori Province of Armenia, where the species was discovered.

DESCRIPTION. Female. Body: moderately stout; the largest collected $ has bl. 4.5 mm.

Antenna I ( Fig. 16 a ) about 55% of body length, about 1.9X longer than antenna II; primary flagellum with 11 segments, with aesthetascs on distal segments; accessory flagellum 2-segmented, distal segment about 2.3X shorter than basal one ( Fig. 16 b ).

Antenna II ( Fig. 16 c ): gland clone distinct, distally pointed; peduncle about 2.1X longer than flagellum, with robust setae tightly covering segments III and IV; peduncle of segment four about 1.1X longer than segment 5; flagellum 6-segmented.

Mandible ( Fig. 17 c–f ): left mandible ( Fig. 17 c, d ) incisor 5-dentate, lacinia mobilis 5-dentate, with three robust plumose accessory setae; molar process with single seta. Right mandible ( Fig. 17 e, f ) incisor 5-dentate, lacinia mobilis toothed, triturative, lobes with numerous protuberances; underlying with a row of two robust plumose setae; molar process similar to left mandible. Palp 3-segmented, segment II with four – five setae; segment III about 3.2–3.3X longer than wide, with seven–eight separate D-setae, two B-seta and four separate E-setae ( Fig. 17 e, g ).

Labrum (upper lip) ( Fig. 17 a ): oval, apical margin with numerous small fine setae.

Labium (lower lip) ( Fig. 17 b ): inner lobes feebly developed.

Lateralia with eight strong pectinate setae.

Maxilla I ( Fig. 17 g ): inner plate with two plumose marginal setae, outer plate with seven apical comb-spines; palp 2-segmented, distal segment pubescent, about 3.0X of basal segment, apical margin of distal segment with seven simple setae.

Maxilla II ( Fig. 17 h ): inner and outer plates covered in pubescent setae, subequal in length; outer plate weakly narrowing distally, with seven apical setae; inner plate narrowing explicitly distally, with group of dense short setae on apex, with an oblique row of four short plumose setae.

Maxilliped ( Fig. 17 i ): inner plate much shorter than outer plate, with two–three spines and single simple seta apically, and three–five simple setae laterally; outer plate narrow, with row of 14–16 medial stiff simple setae of different length; palp quadriarticulate, article I with two simple setae on inner margin, article II with row of 14–16 simple setae on inner margin and without setae on outer margin, article III sub-quadrate; dactylus with single seta on outer margin and without setae at inner margin, nail long, slender, with two thin setae at hinge.

Gnathopod I ( Fig. 16 d, e ): smaller than GnII; coxal plate subtrapezoidal or suboval, slightly narrowing distally, with rounded corners and with four apical and numerous facial setae, width/depth ratio 0.61/1; basis width/length ratio is 0.35/1, with single short seta on anterior margin, three long setae on inner face and four long setae on posterior margin; merus with eight distal setae; carpus is 0.57X of basis and 0.76X of propodus in length, with eight serrated setae in inner margin and four simple setae in outer margin; propodus 1.50X longer than broad, with three simple setae in anterior margin and five serrated single setae in posterior margin; distal margin of palm ( Fig. 16 e ) distinctly or slightly oblique, with double row of four inner and three outer robust setae; palmar groove (depression) feebly developed, with two inner and two outer robust setae; dactylus with single outer seta.

Gnathopod II ( Fig. 16 f, g ): coxal plate subovate, with three apical and numerous facial setae, width/depth ratios is 0.64/1; basis width/length ratio is 0.30/1, with several (two– three) long setae inserted along posterior margin and with two short simple setae in anterior margin; ischium with short simple seta; merus with five distal setae; carpus is 0.57X of length of basis and 0.74X of propodus, with anterior simple seta and three groups of plumose posterior setae; propodus 1.8X longer than broad, with one–two simple anterior setae, three superior medial, three inferior medial and four groups of posterior setae; palm distinctly oblique with double row of four inner and five outer spiniform setae of different size; palm groove (depression) feebly developed, palmar corner ( Fig. 16 g ) with two strong palmar spiniform setae, two supporting bifurcate setae on inner surface; dactylus with single seta along anterior margin and few short setae along inner margin.

Pereopod III ( Fig. 18 a ): coxal plate oval or sub-rectangular, with three apical and numerous facial setae, width/ depth ratio is 0.8/1; basis about 4.4X as long as wide, with long anterior and long posterior simple setae; merus about 0.60X of basis, about 1.33X of carpus and about 1.13X of propodus in length; carpus about 0.85X of propodus in length; dactylus ( Fig. 18 b ) about 0.48X of propodus, with single plumose seta on outer margin and single additional spine accompanying with single seta along ventral margin.

Pereopod IV ( Fig. 18 c ): subequal to PIII in length; coxal plate expanded and broadly convex distally, posterior margin with shallow excavation, distal margin with five apical short setae and numerous facial setae, width/depth ratio is 0.88/1; basis about 4.2X as long as wide, with long anterior and long posterior simple setae; merus about 0.63X of basis, about 1.33X of carpus and about 1.05X of propodus in length; carpus about 0.79X of propodus in length; dactylus ( Fig. 18 d ) about 0.45X of propodus, with single plumose seta on outer margin and an additional spine accompanying with single seta along ventral margin.

Pereopods V, VI, VII with length ratio 1/1.23/1.08.

Pereopod V ( Fig. 18 e ): coxal plate large, bilobate, with distinct anterior and posterior lobes; posterior lobes with three margin simple setae and anterior lobes with single margin simple seta, with numerous facial setae; basis about 1.54X as long as wide, with numerous facial setae, posterior margin slightly convex, armed with six shallow serrations, with distinct distal corner, anterior margin with four split-tipped robust and four distal setae; merus about 0.71X of basis, 0.90X of carpus and subequal of propodus in length; dactylus ( Fig. 18 f ) approximately 0.46X of propodus, with single plumose seta on outer margin and an additional spine accompanying with single seta along ventral margin.

Pereopod VI ( Fig. 18 g ): coxal plate bilobate, with distinct posterior and vestigial anterior lobes; anterior lobe without setae, posterior lobe with single margin seta, each with numerous facial setae; basis about 1.54X as long as wide, with numerous facial setae, posterior margin convex, armed with six shallow serrations, anterior margin with three split-tipped robust and three distal setae; merus about 0.69X of basis, 0.90X of carpus and 0.93X of propodus in length; dactylus ( Fig. 18 h ) approximately 0.36X of propodus, with single plumose seta on outer margin and single additional spine accompanying with single seta along ventral margin.

Pereopod VII ( Fig. 18 i ): coxal plate small, semi-lunar, with single posterior seta; basis about 1.63X as long as wide, with numerous facial setae, posterior margin convex, armed with eight serrated setae in distal corner; anterior margin with three split-tipped robust and three distal setae; merus about 0.56X of basis, subequal of carpus and about 0.88X of propodus in length; dactylus ( Fig. 18 j ) approximately 0.48X of propodus in length, with single plumose seta on outer margin and single additional spine accompanying with single seta along ventral margin.

Gills, brood plates ( Fig. 18 ): coxal gills on somites II–VI, somites V–VIII with lanceolate sternal gill on each. Coxal gills of pereopods II–VI elongated, narrow, gills/bases ratios are 0.72/1, 0.69/1, 0.78/1, 0.80/1 and 0.78/1, respectively.

Pleopods ( Fig. 19 e, f ): pleopods I peduncle with two coupling hooks in retinacula ( Fig. 19 h ), without lateral setae; outer and inner rami with five and six segments, respectively; basal segments of outer ramus with single clothes-pin seta. Pleopod II peduncle with two coupling hooks in retinacula, without setae; outer and inner rami with five segments, respectively; basal segment of outer ramus with single clothes-pin seta. Pleopod III peduncle with two coupling hooks in retinacula, without setae; outer and inner rami with four and five segments, respectively; basal segment of outer ramus with single clothes-pin seta.

Epimera. Epimeral plate I ( Fig. 19 a ) subovate, pointed distally, ventral margin with one spine, posterior margin convex, with one site. Epimeral plate II ( Fig. 19 b ) weakly produced distally, bluntly pointed distally, ventral margin armed with three spines, posterior margin slightly oblique, with three setae. Epimeral plate III ( Fig. 19 c ) subtrapezoidal, blunted distally, ventral margin armed with three spines, posterior margin slightly oblique, with single seta.

Urosomites fused partially: Urosomite I completely free, urosomites II–III fused, with distinct suture ( Fig. 20 c ).

Uropod I ( Fig. 19 g ): peduncle about 3.6X as long as wide, with dorsoexternal row of nine spines and single subdistal short spine; exopodite about 0.9X of endopodite in length; endopodite not paddle-like, with six dorsal, single dorsolateral and five apical thin spines; with five dorsal, two dorsolateral and five apical thin spines.

Uropod II ( Fig. 19 h ): peduncle about 2.0X as long as wide, subequal of endopodite in length, with four dorsoexternal long spines; exopodite about 0.90X of endopodite in length, with four dorsal, single dorsolateral and five apical robust spines; endopodite with six dorsal, single dorsolateral and five apical robust spines.

Uropod III ( Fig. 19 i ): uniramous, peduncle cylindricalshaped, about 2.1X as long as wide, without terminal «knob», two spines on apical margin; peduncle about 1.4X of ramus in length; inner margin of ramus without setae, outer margin of ramus armed with single spine, apical margin armed with three spines.

Telson ( Fig. 19 d ): subrectangular, elongated, 0.72X as long as broad, slightly longer than uropod III; apical margin cleft about 0.50X of total length; with five apical spines and two additional submarginal plumose setae on each lobe.

COLORATION. The body and appendages unpigmented, without well-developed pigmented eyes.

GENBANK ACCESSION NUMBERS. LK028567, LK028568 .

TAXONOMIC REMARKS. The species can be most easily separated from D. waschuschtii by the following features: 1) rami of uropod III with single spiniform spine on lateral margins ( Fig. 19 i ) vs. rami of uropod III without lateral spines [ Behning, 1940, fig. 17n]; 2) propodus of gnathopod II is relatively short, suboval in shape ( Fig. 16 f ) vs. propodus of gnathopod II is elongated, subrectangular shape [ Behning, 1940, fig. 17c]; 3) epimeral plates II–III with three thin spiniform setae on ventral margin, each ( Fig. 19 b, c ) vs. epimeral plates II–III with single thin seta on ventral margin, each [ Behning, 1940, fig. 18j].

The species can be most easily separated from Diasynurella kiwi Marin et Palatov sp.n., by the following features: 1) urosomites II–III completely fused ( Fig. 20 c ) vs. all urosomites completely free ( Fig. 11 a ); 2) uropod III is subequal to telson in length ( Fig. 20 c ) vs. uropod III is much longer than telson ( Fig. 11 a ); 3) inner plate of maxilla I with two plumose marginal setae ( Fig. 17 g ) vs. inner plate of maxilla I with four plumose marginal setae ( Fig. 3g ).

The species can be most easily separated from Diasynurella dzhamirzoevi Palatov et Marin sp.n., by the following features: 1) apical margin cleft of telson is about half of its total length ( Fig. 19 d ) vs. apical margin cleft of telson is more than half of its total length ( Fig. 10 e, f ); 2) propodus of gnathopod II is relatively short, suboval in shape ( Fig. 16 f ) vs. propodus of gnathopod II is elongated, subrectangular shape ( Fig. 7 f ); 3) epimeral plate I with distinct spiniform seta on ventral margin ( Fig. 19 a ) vs. epimeral plate I without setae on ventral margin ( Fig. 10 a ).

The species can be most easily separated from Diasynurella cavatica Palatov et Marin sp.n., by the following features: 1) propodus of gnathopod II is relatively short, suboval in shape ( Fig. 16 f ) vs. propodus of gnathopod II is elongated, subrectangular shape ( Fig. 12 f ); 2) epimeral plate I with distinct spiniform seta on ventral margin ( Fig. 19 a ) vs. epimeral plate I without setae on ventral margin ( Fig. 15 a ); 3) outer and inner rami of pleopods I–III heavily shortened and consist of five and six, five and five, and four and five segments, respectively ( Fig. 19 e ) vs. and inner rami of pleopods I–III of normal length and consist of eight and ten, eight and ten, and seven and eight, respectively ( Fig. 15 e ).

DISTRIBUTION AND ECOLOGY. The species is known only from few nearby weakly flowing springs of alpine zone of the Khalab Ridge in Lori, Armenia (the Lesser Caucasus). It is possible that the species can live in other nearby springs and groundwaters, however, like other species, it is extremely difficult to find due to its very small size and habitat in bottom sediment.

Figures

Fig. 16. Diasynurella khalabensis Palatov et Marin sp.n., Armenia, Lori region, Khalab Ridge: a — antenna I; b — accessory flagellum of antenna I; c — antenna II; d — gnathopod I; e — distoventral palmar margin of chela of GnI; f — gnathopod II; g — distoventral palmar margin of chela of GnII. Рис. 16. Diasynurella khalabensis Palatov et Marin sp.n., АрмениЯ, ЛорийскаЯ область, Халабский хребет: a — антенна I; b — вспомогательный жгутик антенны I; c — антенна II; d — гнатопода I; e — дистовентральный край ладони клеШни GnI; f — гнатопода II; g — дистовентральный край ладони клеШни GnII.

Fig. 17. Diasynurella khalabensis Palatov et Marin sp.n., Armenia, Lori region, Khalab Ridge: a — labrum (upper lip); b — labium (lower lip); c — left mandible; d — same, incisor process and pars incisiva; e — right mandible; f — same, incisor process and pars incisiva; g — maxilla I; h — maxilla II; i — maxilliped. Рис. 17. Diasynurella khalabensis Palatov et Marin sp.n., АрмениЯ, ЛорийскаЯ область, Халабский хребет: a — верхнЯЯ губа; b — нижнЯЯ губа; c — леваЯ мандибула; d — то же самое, реЗцовый отросток и pars incisiva; e — праваЯ мандибула; f — то же самое, реЗцовый отросток и pars incisiva; g — максилла I; h — максила II; I — максиллипед.

Fig. 18. Diasynurella khalabensis Palatov et Marin sp.n., Armenia, Lori region, Khalab Ridge: a — pereopod III; b — dactylus of PIII; c — pereopod IV; d — dactylus of PIV; e — pereopod V; f — dactylus of PV; g — pereopod VI; h — dactylus of PVI; i — pereopod VII; j — dactylus of PVII. Рис. 18. Diasynurella khalabensis Palatov et Marin sp.n., АрмениЯ, ЛорийскаЯ область, Халабский хребет: a — переопода III; b — дактилус PIII; c — переопода IV; d — дактилус PIV; e — переоподаV; f — дактилус PV; g — переопода VI; h — дактилус PVI; i — переопод VII; j — дактилус PVII.

Fig. 19. Diasynurella khalabensis Palatov et Marin sp.n., Armenia, Lori region, Khalab Ridge: a — epimeral plate I; b — epimeral plate II; c — epimeral plate III; d — telson; e — pleopod I; f — hooks of retinacula of pleopod II; g — uropod I; h — uropod II; i — uropod III. Рис. 19. Diasynurella khalabensis Palatov et Marin sp.n., АрмениЯ, ЛорийскаЯ область, Халабский хребет: a — ЭпимеральнаЯ пластинка I; b — ЭпимеральнаЯ пластинка II; c — ЭпимеральнаЯ пластинка III; d — тельсон; e — плеоподаI; f — крючки ретинакулы плеоподы II; g — уропода I; h — уропода II; i — уропода III.

Fig. 20. Diasynurella cavatica Palatov et Marin sp.n. (a, b) and D. khalabensis Palatov et Marin sp.n. (c–h): a, c — urosomal segments, lateral view; b, d — head; e — chela of gnathopod I; f — distoventral margin of chela of gnathopod I; g — chela of gnathopod II; h — distoventral margin of chela of gnathopod II. Рис. 20. Diasynurella cavatica Palatov et Marin sp.n. (a, b) и D. khalabensis Palatov et Marin sp.n. (c–h): a, c — уросомальные сегменты, вид сбоку; b, d — голова; e — клеШнЯ гнатоподы I; f — дистовентральный край клеШни GnI; g — клеШнЯ гнатоподы II; h — дистовентральный край клеШни GnII.

Fig. 11. Diasynurella kiwi Marin et Palatov sp.n. (a, b, h) and D. dzhamirzoevi Palatov et Marin sp.n. (c–g): a, c — urosomal segments, lateral view; b, d — head; e — gnathopod I; f — chela of gnathopod I; g, h — dactyli of ambulatory pereiopods (legs). Рис. 11. Diasynurella kiwi Marin et Palatov sp.n. (a, b, h) и D. dzhamirzoevi Palatov et Marin sp.n. (c–g): a, c — уросомальные сегменты, вид сбоку; b, d — голова; e — гнатопод I; f — клеШнЯ гнатоподы I; g, h — дактилусы амбулаторных переопод (ног).

Fig. 3. Diasynurella kiwi Marin et Palatov sp.n., Russia, Rostov Oblast’, Rostov-on-Don: a — labrum (upper lip); b — labium (lower lip); c — left mandible; d — same, incisor process and pars incisiva; e — right mandible; f — same, incisor process and pars incisiva; g — maxilla I; h — maxilla II; i — maxilliped. Рис. 3. Diasynurella kiwi Marin et Palatov sp.n., РоссиЯ, РостовскаЯ область, Ростов-на-Дону: a — верхнЯЯ губа; b — нижнЯЯ губа; c — леваЯ мандибула; d — то же самое, реЗцовый отросток и pars incisiva; e — праваЯ мандибула; f — то же самое, реЗцовый отросток и pars incisiva; g — максилла I; h — максилла II; i — максиллипед.

Fig. 10. Diasynurella dzhamirzoevi Palatov et Marin sp.n., Russia, Dagestan, Magaramkent district, Samur forest: a — epimeral plate I; b — epimeral plate II; c — epimeral plate III; d — urosomal segments, lateral view; e, f — telson; g — pleopod III; h — hooks of retinacula of pleopod II; i — uropod I; j — uropod II; k — uropod III. Рис. 10. Diasynurella dzhamirzoevi Palatov et Marin sp.n., РоссиЯ, Дагестан, Магарамкентский район, Самурский лес: a — ЭпимеральнаЯ пластинка I; b — ЭпимеральнаЯ пластинка II; c — ЭпимеральнаЯ пластинка III; d — уросомальные сегменты, вид сбоку; e, f — тельсон; g — плеопода III; h — крючки ретинакулы плеоподы II; i — уропода I; j — уропода II; k — уропода III.

Fig. 7. Diasynurella dzhamirzoevi Palatov et Marin sp.n., Russia, Dagestan, Magaramkent district, Samur forest: a — antenna I; b — accessory flagellum of antenna I; c — antenna II; d — gnathopod I; e — distoventral palmar margin of chela of GnI; f — gnathopod II; g — distoventral palmar margin of chela of GnII. Рис. 7. Diasynurella dzhamirzoevi Palatov et Marin sp.n., РоссиЯ, Дагестан, Магарамкентский район, Самурский лес: а — антенна I; b — вспомогательный жгутик антенны I; c — антенна II; d — гнатопода I; е — дистовентральный край клеШни GnI; f — гнатопода II; g — дистовентральный край клеШни GnII.

Fig. 12. Diasynurella cavatica Palatov et Marin sp.n., Georgia, Samegrelo-Zemosvaneti, Chkhorotsqu district, Garakha Cave: a — antenna I; b — accessory flagellum of antenna I; c — antenna II; d — gnathopod I; e — distoventral palmar margin of chela of GnI; f — gnathopod II; g — distoventral palmar margin of chela of GnII. Рис. 12. Diasynurella cavatica Palatov et Marin sp.n., ГруЗиЯ, Самегрело – ВерхнЯЯ СванетиЯ, Чхороцкуский район, пеЩера Гараха: a — антенна I; b — вспомогательный жгутик антенны I; c — антенна II; d — гнатопода I; e — дистовентральный край ладони клеШни GnI; f — гнатопода II; g — дистовентральный край ладони клеШни GnII.

Fig. 15. Diasynurella cavatica Palatov et Marin sp.n., Georgia, Samegrelo-Zemosvaneti, Chkhorotsqu district, Garakha Cave: a — epimeral plate I; b — epimeral plate II; c — epimeral plate III; d — telson; e — pleopod III; f — hooks of retinacula of pleopod II; g — uropod I; h — uropod II; i — uropod III. Рис. 15. Diasynurella cavatica Palatov et Marin sp.n., ГруЗиЯ, Самегрело – ВерхнЯЯ СванетиЯ, Чхороцкуский район, пеЩера Гараха: a — ЭпимеральнаЯ пластина I; b — ЭпимеральнаЯ пластина II; c — ЭпимеральнаЯ пластина III; d — тельсон; e — плеопода III; f — крючки ретинакулы плеоподы II; g — уропода I; h — уропода II; i — уропода III.