Teratothyas (s. str.) digitata, Gerecke, 2020

Gerecke, Reinhard, 2020, The early derivative water mites (Acari: Hydrachnidia, superfamilies Eylaoidea, Hydrachnoidea and Hydryphantoidea) of Madagascar, Zootaxa 4727 (1), pp. 1-77 : 48-49

Teratothyas (s. str.) digitata sp. nov.

Fig. 24 a–b

Type series: Holotype ♂, MNHN Ac 1362, MD 194, Forêt Mandraka (Antananarivo), small stream W R.N. 2 (km 65), left riparian spring 1240 m, S 18°55’03.6’’, E 047°54’57.5’’, 05.04.2011, slide mounted . Paratypes: same site and date, (1/2/0) slide mounted, Ac 1363-1365; (0/6/0) in liquid, Ac 1444.

Other material examined: MD 161, 20.11.2001 Joffreville (M. d’Ambre, Antsiranana), riparian springs at R de Manques in Reserve Fontenay, 730 m, (0/1/0) slide mounted, Ac 1366; MD 165a, 21.11.2001 Joffreville (M. d’Ambre, Antsiranana), R Antomboka downstr. large cascade, 850 m, riffle, (0/1/0) slide mounted, Ac 1367; (4/1/0) in liquid, Ac 1445.

Diagnosis: Membranous parts of integument with densely-arranged, long papillae. Genital field ( Fig. 24 a ) with Ac-1 and Ac-2 relatively long (Ac-1, 35–43, Ac-2, 39–50 % genital flap L); medial genital flap margins in posterior 2/3 subparallel, their posterior end rectangular. Leg claws with obtuse-angled to rectangular basal blade. Palp: Fig. 24 b; L /H ratio P-2, 1.7–1.8, P-3, 1.4–1.6, P-4, 4.9–5.6; P-4 mediodistal margin at peg seta insertion pointed.

Description: Integument papillae long and narrow, cannelated as in T. proceripapillata . Pores of idiosoma sclerites rather large (<10 per transect on dorsocentralia), inner trabecular structures prominent in posteroventral and dorsolateral plates, but barely visible in dorsocentralia. Legs relatively slender, claws with a projecting, obtuseangled or rectangular basal blade.

Genital field with relatively large Ac-1/-2, embraced anteriorly by a trapezoidal bay made up by posteromedial margins of Cx-IV and medially extending sclerite arms, posteriorly by trabecular sclerites forming obtuse lateral angles.

Gnathosoma, chelicerae and palp setation similar to mouthparts of T. proceripapillata , cheliceral claw relatively strong (basal segment/claw ratio 0.8). Palp ( Fig. 24 b ) relatively slender, P-1 elongate (18–19 % total L, L/H 1.7– 1.9), narrowed in the centre; P-2 and -3 distally hardly expanding; P-4 long and slender (L/H 4.9–5.6), maximum H in distal part, distal margin forming an acute angle at the insertion of the pointed distolateral peg seta; P-5 slender, with barely curved claws.

Measurements: Male: Idiosoma L/W 1000–1150/650–820; coxal field L/W 530–610/540–630; Cx-I+II L/W 320–360/210–240; Cx-III+IV L/W 370–410/175–300; genital field L/W 160–180/185–210; maximum diameter Ac-1, 60–63, Ac-2, 63–80 Ac-3, 60–63, ejaculatory complex L 170; gnathosoma L 215–250; palp total L 363; L, L/H ratio, relative L [% total L] palp segments: P-1, 68, 1.69, 19; P-2, 63, 1.72, 17; P-3, 58, 1.64, 16; P-4, 135, 4.91, 37; P-5, 40, 3.2, 11. Leg segments L/H, L/H ratio: I-L-2, 88–110, 1.84–2.00; I-L-3, 75–95, 1.65–1.67; I-L- 4, 120–140, 2.67–2.80; I-L-5, 130–150, 3.25–3.33; I-L-6, 130–145, 2.48–2.52; claw L 38–45; II-L-2, 110–125, 2.17–2.44; II-L-3, 80–110, 1.88–2.00; II-L-4, 155–200, 3.64–3.88; II-L-5, 160–203, 4.26–4.57; II-L-6, 150–165, 2.75–3.33; claw L 45–50; III-L-2, 105–110, 2.00–2.21; III-L-3, 90–100, 1.89–1.90; III-L-4, 170–180, 3.60–3.78; III-L-5, 175–190, 4.12–4.47; III-L-6, 145–170, 2.90–3.09; claw L 40–48; IV-L-2, 125–140, 2.33–2.50; IV-L-3, 110–140, 2.43–2.44; IV-L-4, 215–260, 4.52–4.78; IV-L-5, 205–240, 5.13–5.33; IV-L-6, 175–205, 3.50–3.73; claw L 45–55. Total L segments 2-6: I-L, 543–640; II-L, 655–803; III-L, 685–750; IV-L, 830–985.

Females: Idiosoma L/W 1000–1250/600–900; coxal field L/W 640–680/600–660; Cx-I+II L/W 330–360/240; Cx-III+IV L/W 360–500/300–430; genital field L/W 190–200/210–220; maximum diameter Ac-1, 70–83, Ac-2, 90–95, Ac-3, 60–68; gnathosoma L 250; chelicera total L 420, basal segment/claw 0.8, L/H 6.0; palp total L 360; L, L/H ratio, relative L [% total L] palp segments: P-1, 56, 1.86, 18; P-2, 68, 1.80, 19; P-3, 50–55, 1.43–1.57, 15; P-4, 135–140, 4.91–5.60, 38; P–5, 38, 2.73, 10. Leg segments L/H, L/H ratio: I-L-2, 105, 1.91; I-L-3, 95, 1.81; I- L-4, 150, 3.00; I-L-5, 150–155, 3.33–3.44; I-L-6, 143–145, 2.48–2.52; claw L 45; II-L-2, 130, 2.08; II-L-3, 115, 2.00; II-L-4, 205, 3.73; II-L-5, 205, 4.56; II-L-6, 175, 3.04; claw L 48; III-L-2, 110, 2.00; III-L-3, 95, 1.73; III-L-4, 190, 3.62; III-L-5, 145, 3.22; III-L-6, 180, 3.27; claw L 45; IV-L-2, 145, 2.23; IV-L-3, 130, 2.17; IV-L-4, 280–285, 4.96–5.09; IV-L-5, 250, 4.76–5.56; IV-L-6, 205–215, 3.42–3.74; claw L 55–60. Total L segments 2–6: I-L, 650; II-L, 830; III-L, 720; IV-L, 1020.

Derivatio nominis: digitata (Latin) : with a finger, with reference to the pointed, elongated P-4.

Remarks: Teratothyas digitata is similar to T. proceripapillata in the shape of integument papillae, idiosoma plates and genital field (the latter with slightly larger acetabula, in particular Ac-3). The most remarkable difference in comparison with T. proceripapillata (in parentheses) concerns the longer and more slender palp, with a total L of 360 (<330), an elongated P-1 with a L/H ratio of 1.7–1.9 (<1.5) and a very slender, apically pointed P-4, with a L/H ratio of 4.9–5.6, reaching its maximum H in the centre (distal margin obtuse angled, L/H ratio <4.5, maximum H in distal part). Differences are also found in segment proportions: L ratio P-2/-4, 0.46–0.51 (0.53–0.60), P-3/-4, 0.36–0.43 (0.45–0.48).

The description is based on the type series from Forêt Madraka. Specimens from Montagne d’Ambre (MD 161, MD 165) agree, except for the slightly smaller size of the genital field (L/W 150/160, L Ac-1–3, 58, 58, 45) and palp (total L 299, P-4 115) and the pointed distal extension of P-4 (more distinct than in the specimens of the type series).

Habitat: Weakly seeping riparian springs, riffle of a low order stream.

Distribution: Madagascar, endemic; only known from the relict forest area Mandraka east of Antananarivo (Centre) and a site on Montagne d’Ambre (North).

Figures

FIGURE 24. Family Teratothyadidae. a.–b. Teratothyas (s. str.) digitata (MD 194), male; a. genital field; b. palp. c.–f. Teratothyas (s. str.) planipapillata (MD 109); c. female genital field; d.–f. male; d. leg claw; e. gnathosoma with palp; f. chelicera.