New Species of Limnesia and Tryssaturus (Acari, Hydrachnellae) from New Zealand.

Transactions of the Royal Society of New Zealand : Biological Sciences, Volume 11, Issue 7, 16 July 1969, Page 89

New Species of Limnesia and Tryssaturus (Acari, Hydrachnellae) from New Zealand.

C. L. Hopkins,

By

Fisheries Research Division, Marine Department, Wellington

[Received by the Editor, August 30, 1968.]

Abstract

The new species Limnesia testacea and Tryssaturus minutus are described. Both come from lotic environments in New Zealand.

Introduction

This paper describes two new species of Hydrachnellae, both belonging to genera already known to inhabit New Zealand waters (Hopkins 1966, 1967).

Family LIMNESIIDAE

Subfamily LIMNESIINAE

Genus Limnesia ( Duralimnesia) Viets, 1924

Limnesia (Duralimnesia) testacea n.sp. (Fig. 1, A-F)

Material: Holotype male, collected 30/12/65, Dominion Museum catalogue number DM 4/362. Allotype female of same date, catalogue number DM 4/363. Paratype male of same date, catalogue number DM 4/364. Other paratypes (one male, one female) held by author.

Description of Male; Body somewhat flattened, long oval, almost completely sclerotised except for thin band of tissue along body margin between dorsal and ventral shields. Length 510-525/t, greatest width 323-330/*. Dorsum completely covered by oval, sclerotised shield 450-473/* long. Epimera fused to sclerotised ventral surface but with margins distinctly marked; the united Ep. I—II pressed closely up against united Ep. Ill—IV; subcutaneous, hook-like process extends sideways from posterior end of Ep. I and ends beneath Ep. Ill; Ep. IV large, triangular, with apex pointing posterolaterally. External genital area near centre of ventral surface, lying partly in bay formed by Ep. 111-IV; genital aperture flanked on each side by lunate plate carrying three large acetabula; plates fused at each end of genital aperture; a number of small pores lie on outer margin of each plate. Excretory pore at posterior end of ventral surface. Palp moderately slender; P. II with short, thick ventral spine near distal end; P. IV long and slender, with long, fine hair rising ventrally one third of the way from distal end, and a shorter ventral hair at distal end; palp otherwise with few spines or hairs; dorsal lengths of palp segments: P. I 14-15/*, P. II 58-64/*, P. 11l 43-45/*, P. IV 90-92/*, P. V 32/*. Mandible more or less straight, deep,

with strong claw. Legs rather short, without swimming hairs, each segment with several strong spines; each claw with small dorsal clawlet and larger ventral clawlet; ventral clawlet of 111-leg larger than in other legs; IV-leg without claws, ending in short spines with long, fine spine arising just behind tip.

Description of Female: Similar to male except for external genitalia, which have usual female Limnesiid genital flaps covering the acetabula on each side of genital aperture.

Type Locality; Opihi River, Canterbury. Map ref. in map series NZMS 1: S 101, 436867. On coarse gravel and stones in fast water.

Remarks: The subgenus Duralimnesia is characterised by the almost complete sclerotisation of the body in both sexes. It is known from Africa (Viets, 1924; Cook, 1966) and South America (Besseling, 1949). The present species differs from other members of the subgenus in its lack of swimming hairs and in the fact that the male external genitalia are not fused to the Ep. 111-IV.

Family ATURIDAE

Subfamily ATURINAE

Genus Tryssaturus Hopkins, 1967

Tryssaturus minutus n.sp. (Fig. 2, A-F)

Material: Holotype male, collected 26/3/68, Dominion Museum catalogue number DM 4/365. Allotype female of same date, catalogue number DM 4/366. Paratypes (two males, two females) in author’s possession.

Description of Male: Body flattened, posterior borders rounded; Ep. I-111 projecting beyond antero-lateral margins. Length 400-416/*, greatest width 240/*. Dorsal shield sculptured in a reticular pattern of fine ridges. Genital opening near posterior end of ventral surface, rectangular, with a slight triangular trough anterior to it; acetabula on posterior end of body, extending somewhat on to ventral surface; penis skeleton slender. Excretory pore terminal, on a small tubercle. Palp short and thick, with a fine, ventral seta arising from a papilla near distal end of P. IV; ventral surface of P. II smooth; dorsal lengths of palp segments; P. I 16-18 P. II 36P. 11l 16 M , P. IV P. V Legs short and thick with a few long spines at the distal end of each segment, otherwise almost naked; no swimming hairs; claws with clawlets; IV-Leg-5 greatly expanded distally, enclosing base of IV-Leg-6.

Description of Female: Body shape similar to that of male. Length 432/*, greatest width 248/*. Genital area near posterior end of ventral surface, oval, not terminating in anterior trough; acetabula as in male. Legs without swimming hairs; IV-Leg-5 not expanded; all legs of similar construction.

Type Locality: Cave Stream, Canterbury. Map ref. in map series NZMS 1: S 66, 216975. Amongst fine gravel in fast water.

Other Localities: Bealey River and tributaries at Arthur’s Pass, Canterbury (27/3/68); Hatchery Stream, Te Anau (20/3/68); Mangakotukutuku River, Tararua Range (2/7/63).

Remarks: This species is easily distinguished from the other members of the genus so far described (Hopkins, 1967) by its smaller size ( T. spinipes Hopkins, the smallest species previously described, has males of 440/x and greater), and the position of the genital opening which, in both sexes, is set back from the posterior border of the body. The expansion of IV-Leg-5 in the male is a feature also found in the caudate species T. inusitatus Hopkins.

Literature Cited

Besseling, A. J., 1949. Watermijten uit Suriname. Tijdschr. Ent. 91: 159—79. Cook, D. R., 1966. The Water Mites of Liberia. Mem. Am. ent. Soc. 6: 418 pp.

Hopkins, C. L., 1966. A New Species of Limnesia (Acari, Hydrachnellae) from New Zealand. Trans. R. Soc. N.Z., Zool. 8: 1-4.

1967. New Genera and Species of Water Mites (Acari, Hydrachnellae) from New Zealand. Trans. R. Soc. N.Z., Zool. 10: 33-44.

Viets, K., 1924. Diagnosen einiger neuer Hydracarinen. Zool. Anz. 58: 103—6.

C. L. Hopkins, Fisheries Research Division, Marine Department, P.O. Box 19062, Wellington.