Javathyas nasipalpis, 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 : 32-34

Javathyas nasipalpis sp. nov.

Fig. 17 a–h

Type series: Holotype ♀, MNHN Ac 1318, MD 024, 14.08.2001, Ionilahy (Fianarantsoa), area Andriampanjijy, helocrenic spring (spring 1) at left margin of R Asiaha, 220 m, slide mounted.

Further material examined: MD 157, 18.11.2001, Joffreville (M. d’Ambre, Antsiranana), R de Manques in Reserve Fontenay, riparian springs at right affl., 650 m, (0/0/1), Ac 1319; MD 164, 20.11.2001, same area and catchment, riparian spring at R de Manques, 580 m, (0/0/1), Ac 1320, both slide mounted.

Diagnosis: Female genital field ( Fig. 17 b–c) with a large pregenital sclerite (L/W 100/130) and three pairs of Ac; genital flap medial margin posterior to Ac-2 indented (L/W 280/100). P-3 with a rounded, nose-shaped ventrodistal projection, P-4 with two strong, basally inflated ventral setae ( Fig. 17 e ). Male unknown.

Description: Sclerotized areas with large triangular pores arranged in honey-comb-like patterns, separated from each other by fine, needle-like sclerotized bars ( Fig. 17 d ). This type of sclerite structure in deutonymphs found in all dorsal and posteroventral muscle attachment plates (except for the finely porose centre of muscle attachment), but in the adult restricted to the lateral eye plates and marginal and underlying areas of secondary sclerotization of muscle attachment plates. Instead, coxae and appendages of deutonymph and adult, and in the latter also areas of primary sclerotization of muscle attachment plates and glandularia, with medium-sized, round pores. Dorsal plates ( Fig. 17 a ) separated from each other by well-developed membranous interspaces (W: 40–60). Membranous parts of integument densely covered by modified papillae–these on dorsal surface basally narrowed, distally widened to a flattened structure, in vertical view resulting in a squamose aspect, on ventral surface long, vermiform, in vertical view like short lines ( Fig. 17 d ). Central dorsal plate small in size, anterior margin straight, posterior margin equally rounded. Legs as given in Fig. 17 f–i, with numerous very strong setae, in particular density arranged on III- and IV-L. Claws simple, rather short on I-L, a little stronger on II-L, very strong on III-/IV-L. Genital field with large pentagonal pregenital sclerite and elongated Ac-1 and -2. Medial margin of genital flaps posterior to Ac-2 with a small concave indentation. Postgenital sclerite transverse oval in shape due to extensive secondary sclerotization. Excretory pore plate with extended anterior part, flanking posteroventral plates L-shaped, their inner edge forming a rectangular bay including the pair of posteroventral glands flanking the excretory pore (Fgs 17 b, d). Gnathosoma and its appendages slender, palp: Fig. 17 e . P-1 ventral margin strongly protruding in its proximal part, distally abruptly narrowed, with one long and slender dorsal seta; P-2 ventral margin short and concave, dorsal margin equally rounded, bearing three long setae, one in the centre, the other two between centre and distal margin; P-3 parallelogram-shaped, with subparallel dorsal and ventral margins, distoventral margin forming a rounded, noseshaped projection, dorsally two setae in lateromedial and distal position; P-4 dorsal margin equally rounded, bearing one short seta in distal third and distally ending in a short peg-like tip, ventral margin in the centre protruding to form an obtuse angle near the insertion of a very strong seta that ends in a very fine tip; a further similar seta a little more proximally on the medial segment surface; P-5 inconspicuous, with rather long, straight claws. Except for minor dimensions, the above mentioned differences in sclerite structures, lower setae numbers, and shorter papillae in the ventral membranous areas, the deutonymph agrees well with the holotype from most points of view. Both, the characteristic pregenital sclerite and strong setae on P-4 are well developed, only the distoventral projection on P-3 is not developed at this stage.

Measurements: Female: Idiosoma L/W 1230/900; L/W (L/W ratio) frontal shield 500/450 (1.1), anterior central plate 150/230 (0.7), posterior central plate 270/340 (0.8); L/W lateral plates 1–4: 300/170–260/300–220/240– 270/290; Cx-I+II L/W 300/240; Cx-III+IV L/W 490/250. Pregenital sclerite L/W 100/130; genital flap L/W 280/100; diameter Ac-1–3, 100-95-90; postgenital sclerite L/W 90/145; excretory plate L/W 170/125. Gnathosoma L 300; chelicera L 300, ratio L/H 6.9, basal segment/claw 3.8; palp total L 415; L/H, L/H-ratio, relative L [% total L] palp segments: P-1, 40/65, 0.62, 10; P-2, 125/68, 1.85, 30; P-3, 68/78, 0.87, 16; P-4, 140/44, 3.20, 34; P-5, 43/20, 2.13, 10. Leg segments L/H, L/H ratio (basal segments not detached, not measured): I-L-2, 100/90, 1.11; I-L-3, 90/65, 1.38; I-L-4, 115/70, 1.64; I-L-5, 108/58, 1.87; I-L-6, 130/53, 2.48, claw L 30; II-L-2, 130/95, 1.37; II-L-3, 100/90, 1.11; II-L-4, 130/78, 1.68; II-L-5,139/65, 2.00; II-L-6, 165/58, 2.87, claw L 30; III-L-2, 130/95, 1.37; III-L-3, 110/80, 1.38; III-L-4, 130/80, 1.63; III-L-5, 133/65, 2.04; III-L-6, 175/49, 3.59, claw L 48; IV-L-2, 145/118, 1.23; IV-L-3, 105/88, 1.20; IV-L-4, 250/90, 2.78; IV-L-5, 170/74, 2.31; IV-L-6, 155/63, 2.48, claw L 53.

Deutonymphs: Idiosoma L/W 625–670/425–500; L/W (L/W ratio) frontal shield 270–280/270–290 (0.9–1.0), anterior central plate 75–85/110–135 (0.6–0.7), posterior central plate 117–125/150–180 (0.7–0.8); L/W lateral plates 1–4: 135–150/100–110–130–135/148–150–100–110/110–135–135/190; Cx-I+II L/W 180–190/134–140; Cx-III+IV L/W 190–200/135–140. Pregenital sclerite L/W 40/70; provisional genital field L 100–110; diameter Ac-1–2, 50–40; postgenital sclerite L/W 30/35; excretory plate L/W 60/50. Palp total L 270–278; L/H, L/H-ratio, relative L [% total L] palp segments: P-1, 25–27/30–43, 0.63–0.83, 9–10; P-2, 75–76/40–45, 1.67–1.90, 27–28; P-3, 40/38–40, 1.00–1.05, 14–15; P-4, 96–103/30–31, 3.10–3.42, 36–37; P-5, 31–35/15, 2.07–2.33, 13.

Derivatio nominis: nasus (Latin: nose), and palpis (Latin: palp), referring to the nose-shaped distoventral projection of P-3.

Remarks: The female described here agrees with the other species of the genus ( J. triumvirorum K. Viets, 1929 from Southeast Asia and J. cornipes Cook, 1967 from India) in the combination of rather large genital flaps, narrowed in the centre, and the presence of three pairs of Ac. Both species differ from J. nasipalpis in the absence of a large pregenital sclerite, P-3 without a distoventral projection and the two setae on P-4 being fine, hair-like, not basally inflated (K. Viets 1929, Cook 1967). Similarly strong setae on P-4 are found in species of the genus Dacothyas Motaş, 1959 . In view of the particular significance of male secondary characters for classifying Trichothyas -like mites, a definitive assignement of the new species will be possible only after the detection of the male. The decision, not to include the deutonymphs into the type series, is induced by the far distance between the collecting sites. In contrast to the female, the name giving projection on P-3 is not developed, but, as a general rule, deutonymphal palps are less differentiated in comparison to adults. As they share other important diagnostic characters, conspecificity is probable.

Habitat: Weakly seeping springs.

Distribution: Madagascar, endemic. The finding of two deutonymphs far north and an adult in the southeast, both in springs of forested areas, suggests a wide, but scattered distribution.

Figures

FIGURE 17. Family Hydryphantidae, Euthyadinae, genus Javathyas, J. nasipalpis, female (MD 024) (a.–c., e.–i.: originals, D. Cook). a. dorsum; b. venter; c. genital field; d. excretory plate and surroundings; e. palp medially; f.–i. I-IV-L-2-6.