Trichothyas (Lundbladia) paracunctans, 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 : 34-38

Trichothyas (Lundbladia) paracunctans sp. nov.

Figs 18 a–h, 19 a–h

Type series: Holotype ♂, MNHN Ac 1330, MD 032, 18.08.2001 Madiorano (Fianarantsoa), springs at the left border of the stream crossing the railroad at km 51.2 (MD 031), 650 m, slide mounted. Paratypes: Same site as holotype, (0/1/1) slide mounted Ac 1331; MD 011d, 21.07.2001 Anjozorobe (Antananarivo), Ravoandrina, R Ampanakamonty near campsite, 1280 m, upper course, (0/2/0) slide mounted, Ac 1332; MD 016c, 27.07.2001 Anjozorobe (Antananarivo), Ravoandrina, ruisseau Anjajely (affl. of R Ampanakamonty, downstream from affl. MD 015), 1250 m; moss, (0/3/0) slide mounted, Ac 1333-1335; MD 101, 06.10.2001 Ankaratra (Antananarivo), Reserve Manjakatompo, stream NE Andriandahitokana (affl. of R Namatoana), 1800 m, (1/0/0) slide mounted, Ac 1336; MD 147b, 11.11.2001 Andapa (Antsiranana), right affl. R Ambendrana downstream large cascade, 660 m, riparian vegetation, (1/0/1) slide mounted, Ac 1337; MD 198, 11.04.2011, Andringitra National Park (Fianarantsoa), hygropetric stream crossing way to cascades, 1722 m, S 22°08’12.8’’, E 046°53’06.4’’ slide mounted, (0/7/0) slide mounted, Ac 1338-1344; (0/2/0) in liquid, Ac 1439; MD 232, 25.04.2011, Madiorano (Fianarantsoa), R Sakavia, stream crossing the railroad at km 51.2 (same site: MD 031), 650 m, (0/1/0) slide mounted, Ac 1345.

Material examined: Trichothyas cunctans holotype ♂, SMNH 3605; paratype ♀, SMNH 3606; intersex, SMNH 3823. MNHN C 12 B ♂, Ac 1346, Alluaud and Jeannel 45, 03.02.1912 “Camp IV du Kenya, à 4.000 m d’alt., à la limite supérieur des grandes Senecio arborescents no 177, installé au pied d’une falaise entre les deux vallées Haugsburg et Teleki. Date: 1er à 4 février 1912 ... Aquatiques dans un petit torrent gelé le matin (Planaires, larves de Diptères).” ( Alluaud & Jeannel 1912) .

Diagnosis: Both sexes: Rather small (e.g., L idiosoma 870–1100; P-3, 45–50; P-4, 100–110; IV-L-4–6, 190– 245, 150–200, 150–185); anterior central plate as long as wide ( Figs 18 b , 19 a ); terminal segments of posterior legs stout (e.g., L/H III-L-6, 2.5–3.0, IV-L-5–6, 2.6–3.1, 2.2–2.7–see Figs 18 f–g, 19 g–h); cheliceral claw relatively short (ratio basal segment/claw 2.8–3.2); males: posteromedial margin of Cx-IV convex; Ac-1+2 distinctly separated from Ac-3 ( Fig. 18 a, c ); I-L-3 with two strong dorsal setae and several long pinnate distal setae (fig. 18 d).

Description: Integument papillae bluntly pointed, bent posteriorly, interspaces with fine lineation. Coxae and appendages with a fine porosity, on coxal plates slit-shaped, other sclerites with larger pores various in size (small in muscle insertion areas only). Dorsal and posteroventral plates on their internal surface reinforced by trabecular structures. Frontal plate inverse trapezoid ( Fig. 19 a ) to sub-heptagonal ( Fig. 18 b ), anterior central plate subquadratic, posterior plate transverse, dorsolateralia (dl) 1 narrow, trabecular proximal from lateral eyes, dl-2 elongate, dl-3/-4 subquadratic, dl-5 triangular. Venter with a round postgenital sclerite located anterior to the large, rounded excretory pore sclerite. Genital plates with about 8 setae. Palp rather slender, setation as in Fig. 19 d , ventral margin P-3 straight, P-4 slightly concave in proximal third, more distally slightly convex. Leg claws simple, strong. Male: Medial margin Cx-I with a dense row of strong, pinnate setae. Genital plates with a slightly concave lateral margin, posteriorly with a short medial extension touching the anterior margin of Ac-3. Paired posteroventral plates with a concave anteromedial margin. Legs robust, setation as in Fig. 18 d-g: I-L-1–3 very stout, I-L-3 bearing two strong dorsal peg setae and 4–5 pennate distal margin setae, I-L-4 distally strongly enlarge, with 6 strong distal margin setae, I-L-5/-6 club-shaped, with fine setation only; central segments of II-III-L with very strong peg setae on dorsal and distal margins, in IV-L setae less enlarged, on ventral and distal parts. Female: Medial setae on Cx-I finer, not pinnate. Genital plates lateral and medial margins in central part subparallel, anterolaterally extending to flank Ac-1, posteromedially pointed, embracing anterior part of Ac-3. Legs more slender than in males, strong setae less stout (for details see Fig. 19 e–h).

Measurements: Males: Idiosoma L/W 875–1075/575–650; frontal shield L/W (ratio) 320–370/280–320 (1.10– 1.23);anterior central plate L/W (ratio) 130–160/130–160 (0.9–1.1); posterior central plate L/W (ratio) 110–180/170– 200 (0.65–1.0); lateral plates 1–4 L/W 220–260/110–140, 170–220/130–180, 120–160/140–170, 160–220/180–220. Cx-I+II L/W 270–310/200–240, Cx-III+IV L/W 280–340/190–220; pregenital sclerite L/W 30–40/30–35, genital field L 270–320, genital flap L/W 150–180/20–30, maximum diameter Ac-1–3, 50–65, 60–75, 75–95; ejaculatory complex L/W 80–130/40–50, postgenital sclerite L/W 60–83/70–95; excretory plate L/W 95–125/45–70; posteroventral plate L/W 190–230/125–155. Gnathosoma L 250–300; chelicera total L 263–283 (L/H 7.1–7.5); basal segment/claw ratio 3.04–3.20. Palp total L 278–305; L (L/H ratio), relative L [%]: P-1, 33–38 (0.65–0.90), 11–12; P-2, 73–83 (1.61–1.76), 25–28; P-3, 43–50 (0.95–1.06), 16–17; P-4, 98–108 (2.79–3.23), 34–36; P-5, 33–35 (2.00–2.55), 11–13. Leg segments L (L/H ratio) I-L-1, 63–80 (0.64–0.86); I-L-2, 53–80 (0.74–0.94); I-L-3, 55–68 (0.85–0.92); I-L-4, 80–90 (1.31–1.45); I-L-5, 95–108 (1.82–1.90); I-L-6, 103–125 (1.91–2.45), claw L 23–33; II-L-1, 75–100 (0.73–0.98); II-L-2, 73–90 (0.89–1.06); II-L-3, 60–93 (0.96–1.23); II-L-4, 93–125 (1.41–1.61; II-L-5, 108–145 (2.10–2.42); II-L-6, 135–175 (2.73–3.00); claw 35–45; III-L-1, 80–110 (0.73–0.98); III-L-2, 73–118 (0.91–1.42); III-L-3, 63–75 (1.03–1.27); III-L-4, 93–120 (1.54–1.70); III-L-5, 115–150 (2.28–2.50); III-L-6, 145–168 (2.48– 2.83); claw 43–53. IV-L-1, 135–148 (1.32–1.40); IV-L-2, 103–145 (1.16–1.66); IV-L-3, 108–138 (1.48–1.77); IV-L-4, 198–245 (3.11–3.39); IV-L-5, 158–200 (2.86–3.08); IV-L-6, 165–185 (2.33–2.64); claw 53–63.

Females: Idiosoma L/W 925–1100/650–850; frontal shield L/W (ratio) 280–320/290–350 (0.88–1.03); anterior central plate L/W (ratio) 140–170/160–170 (0.88–1.06); posterior central plate L/W 145–200/200–250 (0.60–0.87); lateral plates 1–4 L/W 215–270/120–140, 190–230/170–220, 155–190/160–200, 200–230/220–260. Cx-I+II L/W 230–260/160–220; Cx-III+IV L/W 260–360/155–210; pregenital sclerite L/W 30–50/80–100; genital field L 225– 280; genital flap L/W 150–185/30–50, maximum diameter Ac-1–3, 60–75, 65–85, 60–80; postgenital sclerite L/W 70–140/65–140, excretory plate L/W 90–115/60–70; posteroventral plate L/W 200–220/150–170. Gnathosoma L 240–280, chelicera total L 243–290 (L/H 6.5–7.6); basal segment/claw ratio 2.82–3.14. Palp total L 305–325; L (L/H ratio), relative L [%]: P-1, 35–38 (0.74–0.83); 11–12; P-2, 78–93 (1.60–1.72), 25–28; P-3, 50–50 (0.95– 1.18), 15–17; P-4, 105–110 (3.00–3.14), 34–35; P-5, 33–35 (2.00–2.33), 11. Leg segments L (L/H ratio): I-L-1, 65–68 (0.81–1.04); I-L-2, 75–78 (1.15–1.19); I-L-3, 68–70 (1.17–2.25); I-L-4, 95–103 (1.69–1.78); I-L-5, 105–110 (2.05–2.10); I-L-6, 105–113 (2.13–2.21); claw 28–33; II-L-1, 75–95 (0.83–0.94); II-L-2, 90–100 (1.29–1.46); II- L-3, 75–83 (1.18–1.33); II-L-4, 113–125 (1.79–1.96); II-L-5, 123–135 (2.16–2.38); II-L-6, 133–153 (2.49–2.80); claw 35–43; III-L-1, 73–98 (0.76–0.94); III-L-2, 83–90 (1.09–1.27); III-L-3, 70–85 (1.13–1.39); III-L-4, 110–118 (1.68–1.96); III-L-5, 115–140 (2.19–2.55); III-L-6, 140–160 (2.64–3.00); claw 43–50; IV-L-1, 143–175 (1.33– 1.45); IV-L-2, 115–133 (1.47–2.42);IV-L-3, 113–135 (1.68–2.09); IV-L-4, 190–225 (2.93–3.55); IV-L-5, 150–180 (2.63–2.95); IV-L-6, 150–173 (2.22–2.70); claw 48–58.

Derivatio nominis: par (Latin: similar) & the name of the similar species cunctans (Latin: slow).

Remarks: Since the first description of a representative of this genus ( Michael 1895), authors were impressed by the extraordinary morphological features of Trichothyas and provided high numbers of carefully done figures. At the same time, they often mentioned a high uniformity of populations collected in scattered, distant places in Europe, Africa, Asia and North America. Many character states used for species discrimination in earlier times later proved to be variable, with the consequence that several species were synonymized. Also the separation of the East African T. cunctans (Lundblad, 1951) from the SW Palaearctic (sub)species T. petrophila ( Michael 1895) , T. petrophila rutae (Lundblad, 1941) , T. duplicata (K. Viets, 1954) and T. alborzensis Bader & Sepasgozarian, 1979 , the American T. compressa (K. Viets, 1953) and T. muscicola ( Mitchell, 1953) , and the Asian T. feuerborni (K. Viets, 1929) and T. japonica (Uchida & Imamura, 1953) is still under question.

Male T. paracunctans agree in important points with T. cunctans , described in detail by Lundblad (1952) from Mt. Kilimanjaro ( Tanzania) and in the same year recorded also from Kenya ( Walter & Bader 1952): (1) Ac-1+2 distinctly separate from Ac-3; (2) I-L-3 with two strong dorsal setae only, but with long pinnate distal setae; (3) I-L-4–6 rather slender. However, the following differences result from revision of the type material and comparison with the original description (in parentheses: values for male and female T. paracunctans / types of T. cunctans , rounded): (1) idiosoma, as well as segments of appendages, generally shorter (e.g., L idiosoma 870–1100/1140–1350; P-3, 45–50/55–75; P-4, 100–110/120–160; most leg segments, e.g., IV-L-4, 190–245/250–310; IV-L-5, 150–200/205– 245; IV-L-6, 150–185/205–235); (2) anterior central plate more stout (L/W ratio 0.9–1.1/1.2–1.8); (3) posteromedial margin of male Cx-IV rounded, not concave; (4) terminal segments of posterior legs stouter (L/H III-L-6, 2.5–3.0/3.2–4.0, IV-L-5, 2.6–3.1/3.1–3.6, IV-L-6, 2.2–2.7/2.9–3.4); (5) cheliceral claw relatively shorter (ratio basal segment/claw 2.8–3.2/2.5–2.7).

Several of these differences, in particular absolute measurement values, are of doubtful value for species separation. However, mostly in view of remarkable differences in chelicera and leg segment proportions, the Madagascan populations should be considered as representatives of a sister species of the continental T. cunctans . A male specimen from Mt. Kenya (MNHN C 12 B) agrees in measurements and proportions of appendages with the definition given here for T. cunctans , but has an anterior dorsal shield with a L/W ratio of 1.0 as in T. paracunctans .

Habitat: Middle order streams with hygropetric areas.

Distribution: Madagascar, endemic. In relict rain forests of the centre and East.

Figures

FIGURE 18. Family Hydryphantidae, Euthyadinae, genus Trichothyas, T. paracunctans (originals, D. Cook). a.–g. male; a. venter (detail: pinnate medial seta of Cx-I); b. dorsum; c. genital field; d.–g. I–IV-L (detail in d.: I-L-3, opposite side); h. deutonymph (MD 32), acetabular sclerites.

FIGURE 19. Family Hydryphantidae, Euthyadinae, genus Trichothyas, T. paracunctans female (originals, D. Cook). a. idiosoma, dorsal view; b. idiosoma, ventral view; c. genital field; d. palp.; e.–h. I–IV-L.