Orthocladius van der Wulp

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 : 239-241

Orthocladius van der Wulp ( Figs 55–57 )

Head capsule yellow, brown to dark brown, or reddish brown, occipital margin usually darkened. Antenna 5-segmented (rarely with 4 segments). Premandible with one (frequently notched) or two apical teeth. Mandible with 3 inner teeth, apical tooth usually short, longer in some species of subgenera Euorthocladius and Symposiocladius . Mentum with one median and usually with 6 pairs of lateral teeth, sometimes 7–9 laterals are present ( O. (Symposiocladius) lignicola has unusual mentum with single elongate median tooth and 2 pairs of lateral teeth). Ventromental plates narrow and short, beard absent (with the exception of subgenus Pogonocladius ).

Remarks: Subfossil head capsules of Orthocladius with 6 pairs of lateral mental teeth and without beard are essentially indistinguishable from Cricotopus (incl. Paratrichocladius) as mentioned above (see remarks to Cricotopus ).

The following Orthocladius species have been recorded in the Tatra Mts. lakes: O. (Eudactylocladius) fuscimanus (Kieffer, 1908) , O. (Eudactylocladius) olivaceus (Kieffer, 1911) , O. (Euorthocladius) rivicola Kieffer, 1921 , O. (Euorthocladius) rivulorum Kieffer, 1909 , O. (Mesorthocladius) frigidus (Zetterstedt, 1838) ( Bitušík 2004; Novikmec et al. 2015).

The remains identified as Orthocladius were recorded very rarely in small number of the surveyed lakes. Three morphotypes were distinguished following Schmid (1993) and Soponis (1977), none of them is listed in Brooks et al. (2007).

Key to morphotypes:

1 Median mental tooth extending considerably beyong apieces of first laterals; mentum noticeably triangular in shape; median tooth with first two lateral teeth paler than remaining laterals.............................. Orthocladius dentifer - type

- Median and first lateral teeth subequal in lenghts............................................................ 2

2 Mandibular teeth black; ventromental plates short and narrow; seta submenti located close to bases of ventromental plates, 2 setal pores present.................................................................... Orthocladius frigidus

- Mandibular teeth brown; ventromental plates long extended well below seta submenti, angling inwards apically, setae submenti positioned below the base of ventromental plates.................................... Orthocladius (Euorthocladius)

Figures

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.