Polycentropus ierapetra, Malicky, 1972

Karaouzas, Ioannis & Waringer, Johann, 2017, The larva of Polycentropus ierapetra Malicky 1972 (Trichoptera: Polycentropodidae), including a key to the larvae of genus Polycentropus (Curtis 1835) in the Hellenic western Balkan region, Zootaxa 4294 (5), pp. 586-592 : 588-589

Separation of P. ierapetra from other known larvae of European Polycentropus specie s

The uniform pale background colour of the head capsule of P. ierapetra is similar to that of P. corniger , P. excisus , P. intricatus and P. irroratus , where only dark muscle attachment spots are present. In contrast, the head capsule of P. kingi and P. flavomaculatus have, in addition, distinctly dark bands ( Pitsch 1993, Table 6, figs. 82–84; Waringer & Graf 2011, fig. 11). In P. schmidi , dark bands or muscle attachment spots are completely lacking. Each anal claw of P. ierapetra is obtuse-angled as in P. excisus , P. intricatus , P. irroratus , P. kingi and P. schmidi , whereas in P. corniger and P. flavomaculatus it is right-angled ( Pitsch 1993, Table 6; Vieira-Lanero et al. 2003, fig. 4; Urbanič 2006, figs. 1–3; Waringer & Graf 2011, figs. 10, 16). The frontoclypeal apotome of P. ierapetra and P. irroratus is concolorous whereas two light areas can be distinguished in the apotome of P. excisus , P. flavomaculatus , P. intricatus , and P. kingi ( Vieira-Lanero et al. 2003, fig. 2; Waringer & Graf 2011, figs. 11, 14, 15). The ratios of protarsal length / protibial length are <0.50 in final instar larvae of Polycentropus species known so far except in P. schmidi Novák & Botosaneanu 1965 (0.50–0.58; Urbanič 2006, figs. 1–3) and P. ierapetra (0.72–0.74). When comparing the projected length of the longitudinal axis ‘d’ of muscle attachment spot ‘m’ with the distance between the median border of this spot to the frontoclypeal suture (measured at a right angle of the frontoclypeal suture towards spot center), this distance is greater than ‘d’ in P. excisus ( Fig. 5 ) but equivalent in P. flavomaculatus and P. ierapetra ( Figs. 1 , 6 ).

Ecology. Larvae of P. ierapetra inhabit a wide range of stream habitats, from slow to moderate currents and low to medium water temperatures. Altitudinal distribution ranges from 10 to 1,000 m a.s.l. As their congenerics, larvae build fixed tubular retreats and use associated silk strands to detect vibrations of their prey ( Wiggins 1996). Their microhabitats are composed of cobbles, pebbles, gravel, and abundant coarse particulate organic matter (i.e., fallen leaves, twigs, etc.). Polycentropus ierapetra has two annual, poorly synchronised generations from late April to July and from September to October ( Malicky 2005). Other caddisflies inhabiting the same habitats are Agapetus episkopi Malicky 1972 , Hydroptila aegyptia Ulmer 1963 , H. vectis Curtis 1834 , Oxyethira falcata Morton 1893 , and Hydropsyche pygmalion Malicky 2001 .

Figures

FIGURES 5 – 7. Polycentropus spp., 5 th instar larvae. 5, Polycentropus excisus Klapálek 1894, head, dorsal. 6 – 7, Polycentropus flavomaculatus (Pictet 1834), 5 th instar larva: 6, head, dorsal; 7, left anal claw, left lateral. d = projected length of longitudinal axis of muscle attachment spot ‘ m’; m = muscle attachment spot ‘ m’. Scale bars = 1 mm.

FIGURES 1 – 2. Polycentropus ierapetra Malicky 1972, 5 th instar larva. 1, head and pronotum, dorsal. 2, head and pronotum, right lateral. d = projected length of longitudinal axis of muscle attachment spot ‘ m’; m = muscle attachment spot ‘ m’. Scale bars = 1 mm.