Olecryptotendipes Zorina

Description

Introduction

Medium-sized larvae, up to 8 mm long, colour in life unknown. Body elongate, with 3 thoracic segments, 17 abdominal 'segments' (7 of which are 'accessory').

Dorsal Head

Undescribed.

Antenna

Antenna short, with 6 segments, segment 2 subequal to 3rd, 4th, 5th and 6th short. Lauterborn organs absent, style on apex of 3rd segment (indicating original apex of 2nd segment, subdivided), reaching 5th segment. Ring organ in middle of segment 1, seta absent. Blade apical / subapical on 2nd segment, reaching near apex of antenna, accessory blade undescribed.

Labrum

Bases of SI fused, SI blade-like, SII also blade-like, subequal to SI, apparently without labral chaetae; SIII short, seta-like; SIVA long, '3-segmented', SIVB simple. Labral lamellae absent. Pecten epipharyngis a simple scale with apical notch. Premandible with 3 pointed teeth, brush absent.

Mandible

Mandible with pale, sickle-shaped, dorsal tooth, with apical tooth and 2 inner teeth. Seta subdentalis lanceolate, extending to base of apical tooth. Seta interna of 4 simple main branches. Pecten mandibularis of several fine lamellae, located in basal half of mandible.

Mentum

Mentum with broad rounded-triangular median tooth, paler than 7 pairs of lateral teeth on each side; laterals decreasing in size laterally; mentum flat to almost concave in shape. Each ventromental plate narrower than mentum, very widely separated medially, with distinct striae not reaching anterior margin. Setae submenti strong, simple.

Maxilla

Palp strongly developed, 1st segment weakly sclerotised, about 2.5 times as long as wide.

Body

Posterior parapod elongate, tapering with 10 simple claws. Procercus short. Anal papillae elongate with median constriction

Notes

Taxonomic Notes

Olecryptotendipes resembles Chernovskiia in having a larval body with 'extra' segmemts in the abdomen (each of the first 7 abdominal segments subdivided, giving appearance of 17 against 10) and very elongate posterior parapods. However features of the antenna (short, 6 segmented), mandible (regular-shaped, with inner teeth) and mentum with rounded-triangular pale median tooth and 7 laterals distinguish from Chernovskiia and more resemble Paracladopelma and particularly Saetheria. The presence of a dorsal tooth of the mandible, unusual in Harnischia-complex, is found also in Hanochironomus.

Ecological Notes

Two species of Olecryptotendipes are known: O. lenzi in Primorye Territory, Russia, and O. secundus in Sakhalin, Russia. Larvae of O. lenzi occur in sandy substrates in a river of the far eastern Palaearctic region.

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