Pseudodiamesa nivosa, Goetgehebuer, 1928

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 : 223

Pseudodiamesa nivosa - type ( Figs 17–19 )

This is a new morphotype, not listed in Brooks et al. (2007).

Antennal ratio ≥ 2.5 ( Fig. 17A ). Pecten epipharyngis is characterized by even number (3–4 pairs) strongly sclerotized scales. Labral lamellae present between bases of SI setae. Premandible with more than 10 teeth ( Fig. 19 ). Mandibular seta interna consists of 14–24 branches ( Fig. 18 ).

Mentum with a lighter median tooth compared to the black lateral teeth; outermost lateral teeth are more visible in unflatten mentum ( Fig. 17 ). However, be aware of the fact that first and second instar larvae of both morphotypes has broad median mental tooth that is lighter than the blackish lateral teeth ( Figs 20, 21 ), thus young instars are not sufficient for morphotype identification.

Remarks: This morphotype was the most frequent Diamesinae remain in surface sediments of the Tatra Mts. lakes. Its distribution is consistent with the knowledge of the ecology of the nivosa species group. It is more coldadapted than the P. branickii group, which occurs under more moderate conditions ( Ilyashuk et al. 2010; Hamerlík et al. 2017). One species of the species group, P. nivosa Goetgehebuer, 1928 , was recorded in the Tatra Mts. ( Novikmec et al. 2015).

Figures

FIGURES 15–22. Pseudodiamesa branickii-type: 15— mandible (arrow indicates branches of seta interna). P. branickii-type: 16—detail of pecten epipharyngis and premandible (arrows indicate seven scales of pecten epipharyngis and 8–9 teeth of the premandible). Pseudodiamesa nivosa-type: 17—head capsule, A—antenna. P. nivosa-type: 18—mandible (arrow indicates branches of seta interna). P. nivosa-type: 19—detail of pecten epipharyngis and premandible (arrows indicate premandible teeth, SI setae and detail of labral lamellae). Pseudodiamesa: 20—young instar head capsule. Pseudodiamesa: 21—detail of mentum. Pseudokiefferiella parva: 22—head capsule.