Chironominae Maquart

Description

Introduction

Small to very large, usually red with haemoglobin pigment of varying depth and intensity, sometimes whitish or greenish. Head seldom more than 1.5 times as long as wide. Eye spots usually double, situated one above the other.

Dorsal Head

Frontoclypeal apotome present, or clypeus separated as discrete sclerite, labrum always consisting of several simple and paired sclerites. In a few genera of tribe Chironomini a distinct fenestra is located on anterior frons.

Antenna

Always well-developed, with 5-8 segments, in Harnischia complex sclerotization often is incomplete or very weak, and segmentation difficult to determine, except immediately prior to moulting. Blade shorter than or, occasionally, little longer than flagellum; accessory blade usually fused with and much shorter than blade; occasionally strongly developed and separate. Lauterborn organs usually present and on apex of 2nd segment, occasionally difficult to distinguish or absent, occasionally alternate on apices of segments 2 and 3, sometimes either when opposite or alternate inserted subapically; frequently placed on pedestal in Tanytarsini, never so in Chironomini or Pseudochironomini. Style mostly situated on segment 2, exceptionally on apparent segment 3 (but perhaps actual apex of a divided 2nd segment). In Chironomini or Pseudochironomini antennae arise from rounded protuberances, whereas in Tanytarsini they are on distinct pedestals, usually at least as high as wide and frequently with distal spur.

Labrum

SI seta simple, palmate or plumose, bases usually separate in Chironomini and Pseudochironomini, always fused in Tanytarsini; SII simple in most Chironomini, usually plumose to finely feathered in Tanytarsini and Pseudochironomini, in which may arise from strong pedestal; SIII always fine, simple; SIVa ranges from simple sensillum to very very well developed and on pedestal in some genera of Harnischia complex. Chaetae laterales absent, simple or deeply serrate. Labral lamellae usually well-developed and comb-like, except in Harnischia-complex in which it usually consists of a single scale, often very small, which may or may not be serrated; in Pseudochironomini the pecten epipharyngis consists of 3 single, sclerotized spines; in Tanytarsini the pecten epipharyngis consists of 3 serrate scales, sometimes however consists of 3-5 pointed or digitiform lobes and occasionally it is a single, broad, serrated comb. Premandible almost invariably present and well-developed, with one to 7 teeth and strong brush; seta premandibularis short to very long.

Mandible

With dorsal tooth in Tanytarsini and Chironomini, except Harnischia complex and few other genera; usually with well-differentiated apical tooth and several inner teeth. Pecten mandibularis generally present and well-developed, but usually greatly reduced and or absent in Harnischia-complex. Seta subdentalis almost invariably present and usually simple, inserted ventrally, except dorsally in Pseudochironomini, extending to mola, mid-teeth, or exceptionally  to apical tooth. Seta interna almost always present, with 4 plumose branches. External surface of mandible smooth to rugose or crenulate, molar margin with or without spines.

Mentum

Usually with 9-16 distinct dark teeth, sometimes median region or whole mentum very pale, especially in Harnischia complex; median zone (ventromentum) may be delimited from the lateral regions (dorsomentum) and connected with the ventomental plates. Ventromental plates nearly always well developed, usually with distinct striae; variable in shape from slender, broad, gently curved, only narrowly separated medially to rather narrow; reduced to a few hooks in Stenochironomus.

Maxilla

In general the maxilla has not been studied in enough detail to consistently diagnose, but details of length and shape of the palp is significant in Harnischia-complex.

Body

Procercus and parapods typically well developed. Eleventh body segment of some Chironomini with 1 or 2 pairs of long ventral tubules, in addition short lateral tubules may occur on segment 10. Two pairs of anal tubules usually, varying in size and shape. Body segments 5-9 of most Tanytarsini with characteristic, bifurcate setae, often difficult to see in slide-mounted specimens.

Notes

Ecological Notes

Larvae of Harnischia complex are free-living, obligate or facultative predators. Larvae normally live in fixed (non-transportable tubes), exceptionally in transportable cases similar to those of Trichoptera.

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