Heterotrissocladius Spärck (Figs 48–50)

Head capsule yellow, occipital margin pale or darkened. Antenna 7-segmented, seventh segment vestigial (Fig. 48). Premandible with two indistinct teeth (Fig. 49). Apical mandibular tooth shorter than combined width of 3–4 inner teeth. Mentum with two (rarely one) median teeth (sometimes accessory teeth are present) and 5 pairs of lateral teeth. First and second lateral teeth clearly longer than other three lateral teeth. Ventromental plates distinct, bulbous, extended beyond margin of mentum.

Remarks: Heterotrissocladius is similar to Paratrissocladius, however the latter has 4 lateral mental teeth. Subfossil remains without antennae and labro-epipharyngeal region could be confused with Psectrocladius and Chaetocladius that have distinct ventromental plates. However, the outmost lateral tooth is usually reduced in Chaetocladius, and ventromental plates of obviously triangular shape with weak beard in Psectrocladius .

One morphotype was distinguished.

Heterotrissocladius marcidus - type (Fig. 50)

Mentum with two median teeth. Submentum entirely pigmented, darker than the rest of the head capsule.

Remarks: Heterotrissocladius marcidus (Walker, 1856) is the only known species in the Tatra Mts. lakes, and it is considered to be the most common chironomid inhabiting the Tatra Mts. lakes (Bitušík et al. 2006a).

Subfossil remains were abundant in most of the studied lakes.