Chaetocladius Kieffer, 1911Chaetocladius piger (Goetghebuer, 1913)

Chamutiová, Tímea, Hamerlík, Ladislav & Bitušík, Peter, 2020, Subfossil chironomids (Diptera, Chironomidae) of lakes in the Tatra Mountains an illustrated guide, Zootaxa 4819 (2), pp. 216-264 : 230

Chaetocladius Kieffer ( Figs 29–31 )

Head yellow to light brown with darkened occipital margin. Antenna 5 segmented, never strongly reduced ( Fig. 29A ). Premandible bifid with 1–2 blunt inner teeth ( Fig. 29 ). Labral lamellae of various shape usually well developed between labral setae SI, but can be vestigial or absent ( Fig. 30 ). Apical mandibular tooth shorter than combined width of 3 inner teeth. Mentum with 1–2 median teeth and 5 pairs of lateral teeth, the outermost tooth may be reduced. Ventromental plates usually large, rounded and extending beyond outer lateral mental tooth.

Remarks: The shape of mentum is often the only character that can be used for the identification of subfossils. Parametriocnemus , Paraphaenocladius , Heterotrissocladius have mentum with double median tooth, and 5 pairs of laterals, combined with large ventromental plates extending beyond the outer lateral teeth without beard. Setae submenti of Chaetocladius are arising under the ventromental plates ( Fig. 31 ) while there are located much higher in Parametriocnemus and Paraphaenocladius (see Fig. 58 ). The outermost mental tooth is not reduced in Heterotrissocladius . Metriocnemus, Hydrobeanus and Thienemannia have similar menta, however without large ventromental plates and obviously narrower median teeth/ tooth.

The only Chaetocladius identified to species level from the Tatra Mts. is C. bitusiki Moubayed, 2019 (Moubayed & Bitusik 2019).

The morphotype recognized in our material corresponds to Brooks et al. (2007).

Chaetocladius piger - type ( Fig. 31 )

Mentum with paired median teeth, and 5 pairs of lateral teeth, outermost lateral is minute. Ventromental plates are broad and bulbous ( Fig. 31A ).

Remarks: Head capsules were found in eleven lakes without obvious respect to altitude, however, recent larvae of the genus were typical for lakes and ponds of higher elevations with significant fluctuation of water level ( Hamerlík et al. 2017).

Chaetocladius piger - type ( Fig. 31 )

Mentum with paired median teeth, and 5 pairs of lateral teeth, outermost lateral is minute. Ventromental plates are broad and bulbous ( Fig. 31A ).

Remarks: Head capsules were found in eleven lakes without obvious respect to altitude, however, recent larvae of the genus were typical for lakes and ponds of higher elevations with significant fluctuation of water level ( Hamerlík et al. 2017).

Figures

FIGURES 28–31. Brillia bifida-type: 28—head capsule (arrows indicate fourth and fifth lateral teeth of the mentum and position of seta submenti), A—antenna (arrow indicates second segment). Chaetocladius piger-type: 29—bifid premandible, A—antenna. C. piger-type: 30—labral lamellae (arrow indicates its position). C. piger-type: 31—head capsule (arrow indicates seta submenti), A—detail of mentum (arrows indicate minute last lateral tooth and bulbous ventromental plate).

FIGURES 54–59. Metriocnemus fuscipes-type: 54—head capsule. Orthocladius (Orthocladius) dentifer-type: 55—head capsule. Orthocladius (Mesorthocladius) frigidus: 56—head capsule (arrow indicates seta submenti). Orthocladius (Euorthocladius): 57—head capsule. Parametriocnemus/Paraphaenocladius: 58 (arrow indicates seta submenti). Parorthocladius: 59—head capsule.