Helicopsyche obscura, Rueda Martín, Paola A. & Miranda, Águeda Verónica Isa, 2015

Rueda Martín, Paola A. & Miranda, Águeda Verónica Isa, 2015, Association of immature stages of some caddisfly species from northwestern Argentina with description of a new species of Helicopsyche (Trichoptera: Helicopsychidae), Zootaxa 3949 (2), pp. 203-216 : 205-208

Helicopsyche obscura sp. nov.

( Figs 1 –3)

Helicopsyche obscura sp. nov. resembles Helicopsyche turbida . The new species is recognizable mainly by the general coloration of body and wings (dark grey in H. obscura sp. nov., and medium brown in H. turbida ). Another important character is size, H. obscura sp. nov. is remarkably larger than H. turbida (mean length of each forewing is 9.5 mm in H. obscura sp. nov., 6–7 mm in H. turbida ). The genital segments of the two species are similar, but the differences in the general habitus provide a good way to separate the species. However, some characters of the larva and pupa are the strongest means to differentiate the two species. The larval head of H. obscura sp. nov. is darker than that of H. turbida ; each metanotal plate is divided in four sclerites in the new species, whereas in H. turbida each plate of metanotum consists of two sclerites only. The pupal stage differs in the two species by the shape of the mandibles that are straighter in H. obscura sp. nov.; the posterior hook plates of H. obscura sp. nov. are asymmetrical whereas in H. turbida they are symmetrical; the terminal segment in both species bears a pair of processes but in H. turbida they are more divergent.

The larva of H. murina was associated by Marlier (1964). The illustrated head coloration pattern seems to be similar that of H. obscura sp. nov., but in the description, the metanotum has a central sclerite whereas in H. obscura sp. nov. and H. turbida the metanotal sclerites are distributed symmetrically on either side of a median suture and are without a central plate.

Adult male ( Fig.1 ). Mean length of each forewing 9.5 mm (9.4–9.6, n=5). Forewings with light spots arranged transversally. Maxillary palps of male each two-segmented. General coloration dark grey, with pleural areas yellowish ( Fig. 1 A). Reticulate pattern on sternites III–V. Sternite VI with ventral lobe absent.

Male genitalia ( Fig.1 ). Segment IX annular, with anterior margin straight; posterior margin widened in middle in lateral view ( Fig. 1 B: ix). Tergum X with truncate apex in lateral view ( Fig. 1 B: x); apex of tergum X slightly bifid in dorsal view, bearing strong lateral setae and long setae in dorsal area with sclerotized Y-shaped reinforcement with anterior branches ( Fig. 1 C). Preanal appendages setose, small and rounded ( Fig. 1 B: ap). Inferior appendages widened in lateral view, posterior and dorsal margins of inferior appendages serrate bearing setae ( Fig. 1 B: ai); inferior appendages curved in ventral view ( Fig. 1 D), with internal margins concave, each bearing round basomesal process with short and strong spines, apices of inferior appendages curved mesad and acute. In noncleared males, inferior appendages mostly dark grey, but light yellowish in posterior marginal area. Phallic apparatus slightly curved with apical area membranous; internal sclerite oval ( Fig. 1 E).

5th instar larva ( Fig. 2 ). Mean total length 7 mm (n=3). Head round in dorsal view, frontoclypeus and adjacent parietal areas nearly flat and margined with semicircular carina; generally dark brown with light brown muscular scars in posterior area of fronclypeus ( Fig. 2 A). Pronotum dark brown, with brown muscle scars, internal posterior angles clear, without coloration, anterior margin with yellowish spines and anterior area of pronotum bearing long setae ( Fig. 2 B). Mesonotum brown, with muscle scars in different degrees of light brown; posterior internal margins angulate and strongly sclerotized ( Fig. 2 C). Metanotum with 4 pairs of sclerites, 3 pairs of anteromesal (sa 1) sclerites small and irregular among which largest each bearing 4 setae and 1 pair of posterior subtriangular sclerites (fused sa 2 and sa 3 sclerites) each bearing single seta posteromesally (sa 2) and several setae anterolaterally (sa 3) ( Fig. 2 D). Thoracic legs with chaetotaxy as in Figures 2 E–G. Anal prolegs each with lateral sclerite curved; anal claw elongate with accessory parallel teeth pectinate, arranged like comb ( Fig. 2 H).

Larval case ( Fig. 2 ). Mean anterior diameter: 5 mm (n=3). Made with sand grains attached forming snail–like, helical case ( Fig. 2 I).

Pupa (Fig. 3). Mean body length: 5 mm (4.9–5.1, n=5). Generally dark brown, almost black, with yellowish abdomen. Mandibles curved with wide bases, each with length 2.5 times basal width, apex pointed and internal margin smooth (Fig. 3A). Paired anterior dorsal hook plates on segments II–V, pair of posterior dorsal hook plates on segment IV asymmetrical; general morphology of dorsal hook plates as in Fig. 3B. Terminal abdominal segment rounded, with two divergent digitate processes, each process bearing 1 subapical and 3 apical setae (Fig. 3C).

FIGURE. 3. Helicopsyche obscura sp. nov., pupa: 3A, mandible, ventral; 3B, abdominal segments I–V, dorsal, with details of dorsal hook plates; 3C, terminal abdominal segment, dorsal. 2a–5a=anterior dorsal hook plates of abdominal segments II–V; 4p=posterior dorsal hook plates of abdominal segment IV.

Biological notes. Larvae of this species were collected in slowly running water in mountain rivers. They are associated with rocks and vegetation. The adults were collected mainly during the day, among rocks near the margins of the river. Males and females were seen in copula in August and September. The adults with folded wings were observed on tops of rocks in groups of 5 or 7 individuals making random movements, possibly exhibiting precopulatory behavior.

Etymology. The name of this new species refers to the generally dark color of the adults and larva and the obscure relationship with H. turbida .

Distribution: Argentina (Tucumán).

Material examined. Male holotype: ARGENTINA: Tucumán: Anfama, 2645’ 08,9 S, 06531’22 W, 1169 m, 12.ix.2006, 1 male (IBN).

Paratypes: ARGENTINA: Tucumán: Same data as holotype, 4 males (IBN); Río La Hoyada, Garabatal, 2642’ 4.6 S, 06531’29.1”W, 1270 m, 12.ix.2006, Domínguez et al. cols., 1 metamorphotype male, 3 larvae, 3 pupae (IBN).

Figures

FIGURE 1. Helicopsyche obscura sp. nov., adult male: 1 A, habitus of adult, left lateral; 1 B, genitalia, left lateral; 1 C, genitalia, dorsal; 1 D, inferior appendages, ventral; 1 E, phallic apparatus, left lateral. ix = segment IX; x = tergum X; ap = preanal appendages; ai = inferior appendages.

FIGURE 2. Helicopsyche obscura sp. nov., larva: 2 A, head, dorsal; 2 B, pronotum, dorsal; 2 C, mesonotum, dorsal; 2 D, metanotum, dorsal; 2 E, right foreleg, right lateral-posterior; 2 F, right mid leg, right lateral-posterior; 2 G, right hind leg, right lateral-posterior; 2 H, anal proleg, right lateral; I, larval case.