Axonopsis (Plesiobrachypoda) periyar, Pesic, Vladimir & Reddy, Yenumula Ranga, 2009

Pesic, Vladimir & Reddy, Yenumula Ranga, 2009, New records of water mites (Acari: Hydrachnidia) from interstitial freshwaters of India, with descriptions of three new species, Zootaxa 2158, pp. 20-32 : 30

Axonopsis (Plesiobrachypoda) periyar sp. nov.

( Fig. 6 A-E)

Material examined. Holotype: male, dissected and slide-mounted in Hoyer's fluid. India, Kerala State, River Periyar near Kalady village, 10°09.927' N, 76°26.750' E, 8 m asl., hyporheic zone (temperature 22 o C; pH 8.2), 13 May 2008.

Diagnosis. (only based on male, female unknown). Dorsal shield extending posterior to ventral shield; posterolateral margins of ventral shield with a small pointed projection on each side; two pairs of glandularia lying between the genital field and insertions of the fourth legs; middle of ventral side of P-4 expanded.

Description. Male: dorsal and ventral shields present, these slightly fused at anterior end; dorsal shield oval, truncate anteriorly; dorsal shield L/W 359/247; anterior part of dorsal shield with several small, pointed, posteriorly directed processes on each side ( Fig. 6A ); eye pigment well developed; dorsal shield extending posterior to ventral shield; ventral shield ( Fig. 6B ) L/W 349/278; ventral shield oval, slightly truncate at anterior end; lateral margins of ventral shield with a small pointed projection on each side considerably posterior to the insertions of the fourth legs; tips of first and second coxae produced into pointed, recurved, hook-like processes; posterior margin of first and second coxae with small, pointed, posteriorly directed processes; capitular bay L 96; two pairs of glandularia lying between the genital field and insertions of the fourth legs, these relatively close together; three pairs of genital acetabula, these arranged in an arc; width between most lateral pair of acetabula 111; gonopore elongated L 32; chelicera total L 91; palp ( Fig. 6C ): total L 181, dL and %L (in parentheses): P-1 28 (15.5), P-2 42 (23.2), P-3 27 (14.9), P-4 61 (33.7), P-5 23 (12.7); L P-2/P-4 ratio 0.69; middle of ventral side of P-4 expanded, bearing a relatively heavy seta which lies on a small tubercle. Legs: L of I-Leg-2-6: 27, 26, 41, 58, 61; L of the IV-Leg: 45, 61, 61, 74, 97, 83; IV-Leg-5 ( Figs. 6 D-E) expanded and bearing numerous thickened setae in posterior part of the segment.

Female: unknown.

Discussion. The new species is the second representative of the subgenus Plesiobrachypoda K. Viets, 1942 . The first described species, Axonopsis claviger was been described by Walter (1922) from the White Nile, Sudan. A species from Sri Lanka was reported by Cook (1974) in the collection of Dr. C. H. Fernando, but has not been described.

Compared with Axonopsis claviger , A. periyar sp. nov. can be easily distinguished by the following features: dorsal shield extending posterior to ventral shield (not extending in A. claviger ), posterolateral margins of ventral shield with a small pointed projection on each side (without projection, with an obtuse angle in A. claviger ), two pairs of glandularia lying between the genital field and insertions of the fourth legs (the illustration of A. claviger shows only one pair of glandularia but there are two closely spaced pairs in the specimen from Sri Lanka ( Cook 1974) and middle of ventral side of P-4 expanded (not expanded in A. claviger ).

Etymology. The specific epithet, alluding to the River Periyar , the type locality of the new species, is proposed here as a noun in apposition to the generic name.

Habitat. The single specimen was taken in interstitial waters. However, the well-developed eye pigment suggest that the surface habitat may prove to be the more typical one.

Distribution. Known only from the type locality in Kerala State ( India).

Figures

FIGURE 6 A – E. Axonopsis periyar sp. nov., male: A = dorsal shield; B = idiosoma, ventral view; C = right palp, medial view; D = right IV-Leg- 4 - 6; E = left IV-Leg- 4 - 6. Scale bars = 100 µm.