Hydropsyche siltalai Döhler 1963

Bemmoussat-Dekkak, Soumya, Abdellaoui-Hassaine, Karima, Sartori, Michel, Morse, John C. & Zamora-Muñoz, Carmen, 2021, Larval Taxonomy and Distribution of Genus Hydropsyche (Trichoptera: Hydropsychidae) in Northwestern Algeria, Zootaxa 4915 (4), pp. 481-505 : 483

Hydropsyche siltalai Döhler 1963

( Figs 2 , 3 )

Material examined: Chouly Wadi at Beni Ghazli ( CH 0): 5 mature mƋ pupae ( UTA) and 4 mƋ adults ( UTA), 1 Ƌ pupa ( UGS), 1.v.2015; 1 Ƌ pupa ( UTA), 14.v.2016; 2 Ƌ pupae ( UTA), 17.v.2017; 1 Ƌ pupa ( UTA), 08.v.2017 and 4 Ƌ reared adults ( UTA), 08.v.2017; Chouly Wadi Yebder ( CH 1): 2 mature mƋ pupae ( UTA) , 1 Ƌ imago ( UTA), 14.v.2016; 1 Ƌ imago ( UTA), 13.v.2019; Safsaf Wadi downstream of the El Ourit Area (SK1): 5 mƋ ( UTA) ; 2 mƋ adults ( UTA, UGS), 25.vii.2016; 3 mƋ adults ( UTA), 21.x.2019; Chouly Wadi in Beni Ghazli ( CH 0): 55 H. siltalai morphotype 1 larvae ( UTA) ; Chouly Wadi in Yebdar ( CH 1): 192 H. siltalai morphotype 2 larvae ( UTA) ; Safsaf Wadi (SK1): 154 morphotype 2 ( UTA, UGS) ; Khemis Wadi (KH1): 62 morphotype 2 ( UTA, UGS) .

Description: Body length of fifth-instar larva ranging from 12.5 to 14.0 mm. Morphotype 1 with head and pronotum very light brown ( Figs 2A, 2B ); morphotype 2 darker ( Figs 3A, 3B ). Specimens collected in Algeria morphologically identical to their French or Spanish conspecifics, except for small difference in shape of median spot on frontoclypeus, slightly wider in morphotype 1 and longer and bifurcate in morphotype 2. Oral and aboral light spots of apotome joined in morphotype 1 ( Fig. 2B ) and not joined in morphotype 2 ( Fig. 3B ). In both morphotypes, lateral parts of submentum short and wide ( Figs 2C , 3C ) and prosternites pigmented ( Figs 2D , 3D ).

Distribution and ecology: The distribution area of H. siltalai covers Western Europe (West Palearctic species). Hildrew & Edington (1979) have described it as a species of “small streams”.

In Europe, H. siltalai appears to be a submontane species that is also present in low mountain streams with altitudes varying between 200–800 m a.s.l and sometimes even below 200 m a.s.l. It is a eurythermal and rheophilic species living in the metarhithral and hyporhithral zones, occurring in microhabitats composed of coarse gravel, stones, boulders, bedrock, woody fragments, macrophytes, mosses, and green algae ( Graf et al. 2008).

This species was collected at only four sites of the Tafna Wadi tributaries. The larvae of the fifth instar were usually collected during March, April, and May at Chouly (1065- 916 m a.s.l.) and Khemis Wadis (723 m a.s.l). However, at Safsaf Wadi, the species was found only in August and September. These sites ( CH 0, CH 1, and SK1) are located at altitudes between 723 and 1065 m a.s.l. where the stream beds do not exceed 4 m width. At the Safsaf Wadi site (SK1), it was even found in a stream bed with small heterometric rocks. Its largest populations have been observed at higher altitudes at Chouly Wadi sites ( CH 0, CH 1). It seems to be a stenothermal rheophilic species inhabiting heterometric blocks and pebbles in clear and poorly mineralized waters with no salinity, very high oxygenation (8.41–10.06 mg /l), and with a low to high level of nitrates (1.78–4.9 mg /l). The microhabitats of this species are devoid of aquatic vegetation, on the other hand the riparian vegetation is very dense.

Figures

FIGURE 2. Hydropsyche siltalai D̂hler 1963, morphotype 1. 2A, head and thorax, dorsal; 2B, cephalic capsule, dorsal; 2C, cephalic capsule; ventral; 2D, posterior prosternites, ventral. [scale bar = 1 mm].

FIGURE 3. Hydropsyche siltalai D̂hler 1963, morphotype 2. 3A, head and thorax, dorsal; 3B, cephalic capsule, dorsal; 3C, cephalic capsule, ventral; 3D, posterior prosternites, ventral. [scale bar = 1 mm].