Babr Kamaltynov & Väinölä

Daneliya, Mikhail E., Kamaltynov, Ravil M., Kontula, Tytti & Väinölä, Risto, 2009, Systematics of the Baikalian Babr (Crustacea: Amphipoda: Pallaseidae), Zootaxa 2276, pp. 49-68 : 56-57

Babr Kamaltynov & Väinölä in Kamaltynov, 2002

Babr Kamaltynov, Väinölä, 2002: 813 ;

Pallasea (partim) Stebbing, 1899: 422; 1906: 374; Sowinsky, 1915: 257; Dorogostaisky, 1922: 117; Pleuracanthus (partim) Garjajev, 1901: 42, [non Gray, 1832 ( Coleoptera )]; Pallasea (Pallasea) (partim) Bazikalova, 1945: 137, Barnard & Barnard, 1983: 480, Takhteev, 2000: 57. Type species. Gammarus lovenii Dybowsky, 1874 .

Revised diagnosis. Body slender, length up to 36 mm. Cuticle of body segments, antennules and antennas with scales. Body segments with sparse short dorsal distal setae. Head slightly convex dorsally. Head and pereonites 1–5 with big marginal conic prominences, almost spine-like, sharp or blunt, bent backwards on posterior pereonites, straight or hooked. Pereonites 6–8 with very small marginal prominences. Pleonites with slight lateral inflations. Uronites with one–two dorso-lateral spine-setae on slight prominences, and setae longer than spine-setae. Uronite 1 convex distally. Rostrum very small, rounded. Interantennal blade of head truncated fronto-ventrally, slightly concave. Coxal plates with slight lateral inflation. Epimera with smoothly rounded posterior angles. Epimeron 1 shorter than 2 and 3, with setae around margin. Epimera 2 and 3 with setae on posterior margin and disto-lateral surface. Telson about as long as uronite 3, entire, with straight lateral margins and small right- or obtuse-angled cleft, four to eleven long setae on lateral margins, and short setae on dorsal side; telson length 1.1–1.5 times its proximal width; proximal width 1.5–1.7 times distal width.

Eyes large, with length about half of head length, strongly convex, oviform, black, occupying interantennal blade. Eye length to width ratio 1.1−1.3. Antenna 1 and antenna 2 approximately equally thin and with long peduncles. Antenna 1 shorter than body, 1.2–1.6 times as long as antenna 2; antennal peduncles equally long. Antenna 1 peduncle segments with sparse bunches of setae, which are about the same length as width of segments; segment 1 with uneven surface and five ventral bunches of one to three setae. Accessory flagellum with two to four subsegments. Antenna 1 flagellum with 21 to 34 subsegments. Antenna 2 peduncle segments with dense ventral bunches of setae, about twice as long as segment width; segment 2 concave dorsally; conus about as long as segment; segment 3 about the same size in length and width; segments 4 and 5 with 8–12 short dorso-medial and long medial and ventral bunches of setae. Flagellum with 5–9 elongated segments, about twice as long as wide; 1st subsegment the same length as two following subsegments together.

Mandibular palp extends as long as antennal segment 4; segment 3 with one or two lateral and two or three medial bunches of setae, three to five long setae on the tip. Distal setae of segment 2 and all setae of segment 3 with thin serration at the tip. Maxilla 1. Right. Inner plate with ten pinnate setae. Outer plate with distal strong claw-setae with one or two distal denticles. Second segment of palpus with three–five short sharp tooth-like spine-setae and one-two outer short strong setae. Left. Palp with six to ten distal strong setae. Maxilla 2. Outer plate frontal margin with stronger and longer setae slightly bent medially at the tip; ratio between length and width 2.1–2.3. Maxillipede reaches the distal margin of antennal segment 1. Basis with two bunches of setae. Basis endite prolonged forward to the half of merus. Ischium with three bunches of setae. Ischium endite barely reaches the half of carpus. Merus with three bunches of setae. Carpus with seven bunches of setae on posterior-medial and three on anterior-medial surface. Propodus with seven dorsal, three ventral and three lateral bunches.

Gnathopods subchelate, with almond-shaped propodites. Gnathopod 2 slightly larger than gnathopod 1. Gnathopod 1. Coxa slightly concave anteriorly and convex posteriorly, elongated. Basis with sparse, long, thin setae, and three distal posterior serrated claw-setae. Ischium with posterior bunch of long setae. Merus with two to four posterior bunches and many long disto-medial setae. Carpus with two–three anterior, one medial and three posterior bunches of setae. Propodus with six anterior, ten medial, nine posterior bunches; posterior bunches also with strong spine-setae. Setae of distal margin of propodus with two distal denticles.

Gnathopod 2. Coxa slightly longer than coxa 1, narrowed distally. Basis anterior margin with 10 bunches of setae. Ischium with a small posterior bunch of setae. Merus with five posterior bunches. Carpus with six or seven bunches of multiple serrated setae on posterior protuberance, three medial bunches and three distal anterior bunches of setae. Propodus with seven to nine posterior bunches of serrated setae.

Pereopod 3 slightly larger than pereopod 4. Dactylus of pereopods 3 and 4 stronger than dactylus of pereopods 5−7. Pereopod 3. Coxa slightly longer than coxa 2, prolonged, convex distally. Anterior margin of basis almost straight, posterior convex, with multiple long dense setae; length 3.0–3.5 times width. Ischium with one or two distal bunches of short setae. Merus with convex anterior and concave posterior margins, and multiple long setae; 1.3 times as long as carpus. Carpus with multiple long setae. Propodus about as long as carpus with multiple dense setae. Pereopod 4. Coxa shorter than coxa 3; anterior margin convex, longer than posterior; distal margin straight, posterior concave. Anterior margin of basis concave.

Pereopods 5−7 long and slender, increasing in size from pereopod 5 to pereopod 7. Posterior margin of basis with long, densely set setae. Ischium anterior margin with two–three bunches of long setae. Merus and carpus with bunches of long setae and one to three spine-setae. Propodus thin, match-like. Dactylus rather thin. Pereopod 5. Posterior margin of basis tapering distally, concave, long setae on anterior and posterior margins. Merus with seven to ten anterior and three to six posterior bunches. Carpus with four to ten anterior and posterior bunches, 1.1–1.5 times as long as merus and 1.2–1.7 times as long as propodus. Propodus with four to six anterior and two to four posterior bunches. Pereopod 6. Posterior margin of basis tapering distally, concave; anterior margin with bunches of spine-setae and many long setae. Merus with seven to eleven anterior and three to seven posterior bunches. Carpus 1.3–1.7 times as long as merus and 1.3–1.9 as propodus. Propodus with three to six anterior and four to six posterior bunches. Pereopod 7 reaches uronite 2. Basis slightly narrowed distally, proximal width 1.3–1.6 times distal width; posterior margin straight, with long setae; anterior margin with long proximal setae and sparse bunches composed of a single spine-seta and additional short setae; length 1.9–2.3 times width. Ischium with two–three bunches. Merus anterior margin with seven to ten bunches, posterior with four to seven bunches. Carpus with 6 to 12 anterior and posterior bunches; 1.4–1.7 times as long as merus and 1.3–1.8 times as long as propodus. Propodus outer margin with four to six bunches of spine-setae, inner with five to seven bunches of long setae.

Uropod 2 slightly longer than protopodite of uropod 1. Protopodites with posterior setae and a distal posterior spine-seta. Exopod and endopod of uropod 2 with one posterior seta or without it. Uropod 3 protopodite with posterior spine-seta, four medial bunches of one–two setae and four anterior-lateral bunches of two–three setae; rami narrow, lanceolate, slightly flattened, with pinnate setae around; exopod slightly longer than endopod, with pinnate setae all around forming bunches, and very small, rudimentary distal segment.

Coloration of fresh specimens. Body and appendages covered by large spots. Head with a dorsal V-shaped spot and lateral ones, body segments with transverse dorso-lateral and lateral spots, coxae of pereopods 1−4 with proximal and distal spots. Segments of appendages with a dark distal zone; basis of pereopods 1−2 with anterior and basis of pereopods 5–7 with posterior spots. Protopodites of uropod 3 and telson entirely dark.

Differential diagnosis. Babr closely resembles Pallaseopsis , but differs in the following characters. Dorsal and lateral spines on body segments absent (present in Pallaseopsis ). Rostrum almost indistinguishable (small but well-established in Pallaseopsis ). Telson about as long as the last abdominal segment (clearly shorter in Pallaseopsis ). Uronites and uropod propodites armed with dorso-lateral spinesetae (only setae in Pallaseopsis ). Pereopod dactyli differ in size among pereopods 3, 4 and 5–7 (all about equal in size in Pallaseopsis ). Setae of pereopods 3, 4 and basis of pereopods 5–7 long and dense (short and sparse in Pallaseopsis ). Posterior margin of pereopod 7 basis slightly concave and narrowing distally (convex and with posterior and anterior margins distally parallel in Pallaseopsis ).

Distribution. Endemic of Lake Baikal.

Habitat and ecology. Littoral-sublittoral (0−35 m), nekto-benthic, psammophilic (sandy or sandy-muddy bottom).