THE STRUCTURE OF THE CHELICERAE IN WATER MITES OF THE GENUS EYLAIS LATREILLE, 1796 (ACARIFORMES)

About author:

O.D. Zhavoronkova, Institute for Biology of Inland Waters of the Russian Academy of Sciences, Yaroslavl Prov., Borok, 152742 Russia

Annotation:

The description of the cheliceral structure of adult water mites of the genus Eylais Latreille, 1796 is given.

Chelicerae (ch) are enclosed with a continuous sclerite ring resulting from the extension of hypos-tomal plicae (hpl) and their complete junction around the preoral opening (por; Figs. 1 b, c, d; 2 a, b, c). Chelicerae are two-segmented and represented by massive broadened basal segments and curved bulb-shaped apical segments (dm; Figs. 3 a-c; 4 a-d). Basal segments are joined dorsally by the film forming pseudocapitulum (pc; Fig. 1 a-c). Cheli-cerae possess only protractor muscles (protr. ch; Fig. 4 a); the retractor musculature is absent. Che-liceral claws are located opposite to membranous appendages (m; Figs. 3 c; 4 b-d). Movable digits are located in a hollow (hch) of the sclerite append-ages of basal segments (ach; Figs. 2 a; 3 a-c; 4 b - d). The junction of a movable digit is supported by two ligaments (lg(, lg ; Fig. 4 b-e). The movement of movable digits takes place due to elevator (elev. dm) and depressor muscles (depr. dm), which are located in the hollow of basal segments (Fig. 4 a-d). The antagonistic muscles contract alternately and make the movable digit to perform arched oscilla-tory movements around the articulation by a short ligament (Fig. 4 b-d).

The water mites E.hamata Koenike, 1897; E.rimosa Piersig, 1899, and E.setosa Koenike, 1897 have a cavity inside a movable digit (hdm), apparent-ly filled with a secret (sa; Fig. 4 d, e). In several cases the duct originated from within the secretory sac was found inside a movable digit (du; Fig. 4 e). This duct opens with a pore (po) in the apical part of the cheliceral claw (sdm; Figs. 1 d; 2 a-d; 3 c; 4 e).

However, further histological investigation is need-ed to understand completely the structure and func-tions of secretory formations associated with the movable digits of water mites of the genus Eylais.

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