Litorogammarus karadagiensis ( Grintsov, 2009 ) Marin & Palatov & Copilaș-Ciocianu, 2023

Marin, Ivan, Palatov, Dmitry & Copilaș-Ciocianu, Denis, 2023, The remarkable Ponto-Caspian amphipod diversity of the lower Durso River (SW Caucasus) with the description of Litorogammarus dursi gen. et sp. nov., Zootaxa 5297 (4), pp. 483-517 : 498-505

Litorogammarus karadagiensis ( Grintsov, 2009) comb. nov.

Figs 9–13

Echinogammarus karadagiensis Grintsov, 2009 : e-23, fig. 1 [type locality—Batiliman, Crimea,].

Material examined. 10 ÔÔ, 10♀♀ , LEMMI — Northeastern Black Sea, Russian Federation, southwestern Caucasus, Krasnodar Krai, Novorossiysk area , Durso village , pebble beach, 44°40’41.1”N 37°33’44.1”E, under the upper layer of pebble and stones, with hand net, coll. Palatov D.M. & Marin I.N., 20.07.2021 .

Diagnosis. Head with oblique anteroventral lobe. Pleon with urosomite I armed with a pair of submedian posterior long simple spines; urosomite II with 1 marginal long spine on each side and a pair of median long spines; urosomite III with 1 long and 1small marginal spines of each side. Antenna I with 3-segmented accessory flagellum. Antenna II without calceoli both in males and females. Gnathopods I–II densely covered with long plumose setae. Pereopods V–VII: basis (article 2) with convex dorsal margin, especially in PV, and well-marked ventral lobes. Epimeral plates with sharp but not produced posteroventral angles.

Short description. Head with oblique anteroventral lobe ( Fig. 13 a ). Eye reniform, well pigmented. Pleon ( Fig. 13 f ) with urosomite I bearing a pair of submedian posterior long simple spines; urosomite II with 1 marginal long spine on each side and a pair of median long spines; urosomite III with 1 long and 1small marginal spines of each side ( Fig. 13 f ). Antenna I smooth, non-setose, with 3-segmented accessory flagellum, with small aesthetascs ( Fig. 9 a, b ). Antenna II slightly shorter that AI, with long ventral setae, without calceoli both in males and females ( Fig. 9 c ). Upper lip (labrum) with convex distal part ( Fig. 10 a ). Lower lip (labium) with mostly reduced inner lobes ( Fig. 10 b ). Mandible with outer lobe subequal to inner lobe, not expanding distally, with short incisor teeth ( Fig. 10 c–f ). Maxilla I with outer plate bearing a marginal row of hairbrush-like setae, with outer lobe subequal to inner lobe, distal segment of palp expanding distally ( Fig. 10 g ). Maxilla II with outer lobe equal to inner lobe, bluntly expanding distally ( Fig. 10 i ). Maxilliped with outer and inner plates wide, distally bluntly rounded, with long plumose setae ( Fig 10 j ). Gnathopod I shorter and wider than GnII, not sexually dimorphic, bearing long plumose setae, propodus (palm) with convex slightly oblique palmar margin ( Fig. 9 d ). Gnathopod II not sexually dimorphic, bearing long plumose setae, subrectangular and elongated, about 3 – 4 times as long as wide, with oblique palmar margin ( Fig. 9 e ). Pereopods V–VII with relatively stout and robust segments armed with short strong spines, basis (article 2) with convex dorsal margin, especially in PV, and well-marked ventral lobes; dactylus stout ( Fig.11 ). Pleopods with 2 elongated hooks and 1–2 thick bristles in retinacules ( Fig. 12 f ). Uropod III similar in male and females, robust, with outer ramus broad, about 4 times as long as wide, with reduced distal article furnished with numerous long simple distal setae ( Fig. 12 i ). Epimeral plates with sharp but not produced posteroventral angles ( Fig. 12 a–c ). Telson entirely clefted, with teardrop-shaped lobes bearing clusters of strong stout apical and submedian spines ( Fig. 12 d ).

Coloration. Body and appendages translucent. Eyes cornea silver or brown.

Body size. The largest collected ♀ has tbl. 4.0 mm; the largest collected Ô has tbl. 4.0 mm.

GenBank accession number. ON258047, ON258095 (Copilaș-Ciocianu et al. 2022).

Habitat and distribution. Widely distributed species presently known along the northeastern Black Sea coast, from Batiliman, Laspi Bay (type locality), Karadag Bay ( Grintsov, 2009, 2016) to Durso (present study). Small pebble-dwelling species, living together with Ch. oliviiformis under the upper layer of the pebble, boulder and stones, where both species forms sufficiently large aggregations of heterosexual and different-aged individuals. For the detailed biological features see Grintsov (2016).

Taxonomic remarks. The complete re-description of the species using SEM micrographs is presented by Grintsov (2022). Litorogammarus karadagiensis ( Grintsov, 2009) comb. nov. can be easily identified among congeners and Echinogammarus -like taxa by long plumose setae densely covering mouthparts and gnathopods, which are actually unique within the Ponto-Caspian amphipods. The species can be also easily identified by 3- segmented accessory flagellum of AII and convex dorsal margin of basis of PV.

Figures

FIGURE 9. Litorogammarus karadagiensis (Grintsov, 2009) comb. nov., ♀: a—antenna I; b—accessory flagellum of antenna I; c—antenna II; d—gnathopod I; e—gnathopod II.

FIGURE 10. Litorogammarus karadagiensis (Grintsov, 2009) comb. nov., ♀: a—upper lip; b—lower lip; c—left mandible; d—same, incisor process and pars incisiva; e—right mandible; f—same, incisor process and pars incisiva; g—left maxilla I; h—palp of right MxI; i—maxilla II; j—maxilliped.

FIGURE 11. Litorogammarus karadagiensis (Grintsov, 2009) comb. nov., ♀: 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.

FIGURE 12. Litorogammarus karadagiensis (Grintsov, 2009) comb. nov., ♀, a–c—epimeral plates I–III; d—telson I; e— pleopod I; f—retinacula of pleopod I; g—uropod I; h—uropod II; i—uropod III.

FIGURE 13. Litorogammarus karadagiensis (Grintsov, 2009) comb. nov., ♀ a—head; b—urosomal segments, lateral view; c—gnathopod I; d—chela of GnI; e—palmar margin of chela of GnI; f—gnathopod II; g—chela of GnII; h—palmar margin of chela of GnII.