Lebertia (Pilolebertia) diakonovoensis, Tuzovskij, 2023

Tuzovskij, Petr V., 2023, A new water mite species of the genus Lebertia Neuman, 1880 (Acari, Hydrachnidae: Lebertiidae) from Yaroslavl Province of Russia, Zootaxa 5315 (5), pp. 485-491 : 485-490

Lebertia (Pilolebertia) diakonovoensis sp.n.

Figures 1–19

Type series: Holotype ♀, slide 8544, Europe, Russia, Yaroslavl Province, Nekouz District, brook near village Diakonovo , depth 0.2–0.5 m, substrate: slit, detritus, stones, 1.06. 2002, leg P. Tuzovskij . Paratypes: same locality as holotype: 2 ♀♀ 16. 06. 2002, 1 ♀ 2. 07. 2002, 1 ♀ 8.08.2005 , 1 ♁ 9.08.2005, 4 dn 26.05.2002, 2 dn 1.06.2002 and 1 dn 12.07.2002.

Diagnosis. Integument thin and smooth, with thin lines locally visible, setae Fch with short proximal furca; coxal shield wider than long; P-2 ventrodistal seta thin; P-3 mediodistal seta halfway between ventro- and dorsodistal setae or slightly towards dorsodistal seta; P-4 slender, tapering distally, both ventral setae shifted to the distal half of segment, ventral margin divided by seta insertions into sectors 3: 2: 1, mediodistal peg-like seta short with rounded tip; IV-Leg-6 with four to five short, spine-like ventral setae.

Description. Both sexes. Colour brown. Integument soft and smooth, with short, thin lines which are especially clearly visible along the idiosoma lateral margins ( Fig. 1 ). Setae Fch ( Fig. 2 ) longer and thicker than other idiosomal setae, with short proximal furca. Trichobothria Fp, Oi and setae Pi not associated with glandularia ( Fig. 3 ), other idiosomal setae associated with glandularia ( Fig. 4 ). Coxal shield ( Fig. 5 ) wider than long (L/W ratio 0.83-0.85). Coxal plates I fused to each other nearly complete, fragment of suture line present only in their posterior portion. Suture line between coxal plates I longer than median length of coxal plates II (Cx-I/Cx II ratio mL 1.36-1.95). Coxal shield bearing two pairs of glandularia (Hv and Pe), Pe located near tips of coxal plates I. Coxal plates II with narrow posterior margin. Genital field with three pairs of unequal acetabula, posterior pair of acetabula smaller than both anterior pairs of acetabula. All coxal plates porous, in additional, coxal plates IV with several relatively large oval cells each. Excretory pore not sclerotized.

Pedipalp ( Fig. 6 ): P-1 short, with single short dorsodistal setae; P-2 large, with concave ventral margin, three short unequal dorsoproximal and two long subequal dorsodistal setae, ventrodistal seta thin, longer than ventral margin but shorter than dorsal one (occasionally longer of segment), inserted slightly away from ventrodistal segment edge; P-3 rather long, with five long setae, bases of two proximal a little separated, mediodistal seta halfway between ventro- and dorsodistal setae or slightly towards dorsodistal seta; P-4 slender, tapering distally, both ventral setae shifted to the distal half of the segment, ventral margin divided by seta insertions into sectors 3: 2: 1, mediodistal peg-like seta short with rounded tip ( Fig. 7 ).

Gnathosoma ventral margin strong convex with posterior indentation, posterodorsal projections well developed and pointed, rostrum short, mouth opening flanking by two pairs of short equal setae ( Fig. 8 ). Chelicera basal segment large and thickened distally, chela short with two rows of fine teeth on the concave side.

Legs II-IV with the following number of swimming setae: four to six on II-Leg-5, five to six on III-Leg-4, 6 to 10 on III-Leg-5, four to eight on IV-Leg-4, 8 to 12 on IV-Leg-5 ( Fig. 9 ). IV-Leg-6 with four to five (occasionally with two) short, spine-like ventral setae. Leg claws with short internal and comparatively long external clawlets, lamella moderately developed with concave ventral margin ( Fig. 10 ).

Female. Posterior margin of coxal plates IV not extending to the posterior margin of genital field, with widely rounded posteromedial edges. Genital field with 13-15 medial and three to four lateral setae, anterior genital sclerite with short posteromedian projection ( Fig. 11 ).

Measurements (n=5). Idiosoma L 1160-1250; coxal shield L 665-740, W 800-875; coxal plate I mL 155-185, coxal plate II mL 95-115; genital flap L 185-195, W 72-85, genital acetabula (ac-1-3) L 65-70, 55-65, 45-55; cheliceral segments L: base 210-228, chela 36-42; pedipalp segments (P–1–5) L/H: 30-36/0.48-0.50, 100-120/60-75, 100-115/42-54, 140-145/42-45, 20-25/15-18; leg segments L: I-Leg-1–6: 60-70, 78-100, 85-95, 125-145, 145-165, 130-145; II–Leg-1–6: 65- 80, 95-120, 98-110, 150-165, 180-205, 180-195; III–Leg-1–6: 70-85, 115-180, 125-150-150, 200-240, 240-270, 220-240; IV–Leg-1–6: 140-175, 130-150, 180-210, 260-285, 270-380, 235-270.

Male. Genital field with about 30 pairs of medial and six to seven pairs of lateral setae, anterior genital sclerite with straight posterior margin ( Fig. 12 ).

Measurements (n=1). Idiosoma L 1125; coxal shield L 725, W 775; coxal plate I mL 185, coxal plate II mL 135; genital flap L 200, W 87, genital acetabula (ac-1-3) L 50-60, 50-60, 30-37; cheliceral segments L: base 235, chela 62; pedip[alp total L 425; pedipalp segments (P–1–5) L/H,: 37/50, 112/70, 100/45, 150/35, 25/15, leg segments L: Leg-1–6: 74, 100, 95, 150, 150, 150; II–Leg-1–6: 75, 110, 115, 170, 200, 195; III–Leg-1–6: 85, 125, 115, 225, 275, 250; IV–Leg-1–6: 165, 150, 200, 275, 290, 270.

Deutonymph. Dorsal surface, structure of integument and capitulum similar to that of adults. Setae Fch long, thin with short proximal furca ( Fig. 13 ). Coxal shield wider than long ( Fig. 14 ). Medial length of coxal plates I longer than suture line between coxal plates II (L median Cx-I/Cx-II ratio 1.28-1.45). Medial margin of coxal plates III+IV concave, posteromedial corners of coxal plates IV widely rounded. Pregenital sclerite free and very small. Pedipalp ( Fig. 15 ): P-1 short without seta; P-2 ventral margin concave, with relatively short dorsoproximal seta and two rather long dorsodistal ones; P-3 with two long distal setae, dorsal setae rather far away from distal edge, P-4 long tapering distally, with concave ventral margin and convex dorsal margin in distal half, ventral margin divided by seta insertions into sectors: 3:2:1. Capitulum ventral margin strong convex ( Fig. 16 ). Chelicera basal segment large with convex dorsal margin and thickened distally, chela short ( Fig. 17 ).

Genital flaps very narrow, fused to each other and forming ring bearing three fine setae on each side ( Fig. 18 ). Both pairs of genital acetabula subequal in shape and size. Excretory pore unsclerotized.

Legs III-IV with the following number of swimming setae: one to two on II-Leg-5, two on III/IV-Leg-4, four to five on III-Leg-5, four to six on IV-Leg-5; IV-Leg-6 with one to two short spine-like ventral setae ( Fig. 19 ).

Measurements (n=7). Idiosoma L 600-660; seta Fch L 95-110; coxal shield L 320-330, W 380-390; coxal plate I mL 95-110, coxal plate II mL 65-85; genital ring L 60-65, W 60-70, genital acetabula (ac-1-2) L 23-25, 20-25; capitulum L 120-125; cheliceral segments L base 120, chela 20-24; pedipalp segments (P–1–5) L: 18-22, 63-66, 57-60, 68-85, 17-19; leg segments L: I-Leg-1–6: 40-45, 42-50, 47-50, 65-72, 75-80, 80-85; II–Leg-1–6: 40-45, 54-60, 54-58, 75-80, 100-105, 105- 110; III–Leg-1–6: 42-48, 60-65, 70-75, 98-108, 135-140, 130-140; IV–Leg-1–6: 78-85, 65-72, 95-100, 125-140, 150-160, 140-160.

Larva. See Tuzovskij (2013), as Lebertia longiseta .

Discussion. The new species is similar to Lebertia inaequalis (Koch, 1837) and L. longiseta Bader, 1955 in the structure of the idiosoma and pedipalp. The new species is more similar to L. inaequalis and differs from it by the following characters (characters states of L. inaequalis are given in parenthesis after Gerecke 2009, Di Sabatino et al. 2010 for adults, Tuzovskij 1990 for deutonymphs):

adults: integument with fine lines, Fig. 1 (smooth), capitulum ventral margin strongly convex near middle, with concave distal part, Fig. 8 (equally convex); coxal field wider than long, (coxal field almost as long as wide or slightly longer than wide); setae Fch with proximal furca, Fig. 2 (without furca); P-2 ventral seta thin, Fig. 6 (rather strong, Fig. 20 ); deutonymph: setae Fch with proximal furca, Fig. 13 (without furca); genital acetabula rather large and subequal in shape and size, Fig. 18 (posterior pair of acetabula large than anterior pair acetabula); coxal plate IV posteromedial angle widely rounded (with a right angle). Lebertia longiseta differs especially from L. diakonovoensis sp.n. by the very long ventrodistal seta on P-2 ( Fig. 21 ), much longer than the segment ( Bader 1955, K.O. Viets 1976, Gerecke 2009).

Etymology. The species epithet diakonovoensis is named after the village in the vicinity where it was collected (Diakonovo).

Distribution. Europea, Russia: Yaroslavl Province.

Habitat. Running waters.

Figures

FIGURES 1–7. Lebertia diakonovoensis sp. n., male: 1—detail of integument; 2—seta Fch; 3—seta Oi; 4—seta Oe; 5—ventral view; 6—pedipalp; 7—P-4, distal part. Scale bars: 1, 2–4 = 100 μm, 5 = 200 μm, 6 = 50 μm, 7 = 25 μm.

FIGURES 8–12. Lebertia diakonovoensis sp. n., male: 8—gnathosoma, lateral view; 9—IV-Leg-4–6; 10—leg claw; 11–12— genital field; 8–11—female, 12—male. Scale bars: 8, 10 = 50 μm, 9, 11–12 = 100 μm, 8 = 200 μm.

FIGURE 13–15. Lebertia diakonovoensis sp. n., deutonymph: 13—seta Fch; 14—coxal shield; 15—pedipalp. Scale bar: 13, 15 = 50 μm, 14 = 100 μm.

FIGURES 16–19. Lebertia diakonovoensis sp. n., deutonymph: 16—chelicera; 17—capitulum, lateral view, 18—genital field, 19—IV-Leg-4–6. Scale bars: 16–18 = 50 μm; 19 = 100 μm.

FIGURES 20–21. Lebertia, subgenus Pilolebertia: 20—L. inaequalis, pedipalp (from Gerecke 2009); 21—L. longiseta, pedipalp (from K.O. Viets 1976).