Pedicia (Amalopis) occulta (Meigen, 1830)

(Figs. 2, 3)

Limnobia occulta Meigen, 1830: 279 (description) Amalopis gumdensis Egger, 1863: 1104 (description) Amalopis opaca Egger, 1863: 1104 (description)

Amalopis pyrenaica Verrall, 1888: 27 (description)

Lectotype designation: A lectotype is herein designated for Limnobia occulta Meigen, 1830. While describing the species, Meigen (1830) did not specify the number of specimens and the exact collection locality. The Meigen collection, deposited in the MNHN, contains a single L. occulta specimen. The single male bears the following data on two labells: " Allemagne (the French name of Germany), Meigen" (hand-written round label) and “ occulta ” (handwritten rectangular label), under catalogue number 259. In cases like this, where no haplotype or syntypes was fixed for nominal species-group taxa established in the original description, a lectotype should be designated (recommendation 73F of The International Code for Zoological Nomenclature, 1999). The specimen is labelled as lectotype (“ Lectotype / Limnobia / occulta Meigen ♂/ L. Ujvárosi, 2009 ”), with a printed red label, and identified as Pedicia (Amalopis) occulta (Meigen, 1830). The specimen is pinned, with only the left leg and wing present. The apex of the terminalia has been removed and pinned together with the specimen in a micro-vial in glycerol. The lectotype is deposited in MNHN.

The locality data of the lectotype male is Solingen (51 º 05’ N, 7 º 11’ E) and is based on the biography of J. Meigen, published by Förster (1974), who stated that J. Meigen spent his last decades in Solingen, Germany, gathering his collections around 1830 in the vicinity of this town.

Re-description of P. occulta based on Meigen’s original male specimen. Body length is 12 mm, wing length 14 mm. It resembles P. f u s c a n. sp. in general appearance (Fig. 2 B), but the body coloration is generally lighter. The head is yellowish brown, dusted with grey; only the frons are darker (Fig. 3 C). Antennae are pedicel yellow and have scape, flagellomeres are yellow (Fig. 4 B). Maxilar palpus is yellowish brown (Fig. 3 C). Stipes are narrower and lighter than in P. f u s c a n.sp. The distal arms of the stipes bear two bristles each, a characteristic not observed in P. f u s c a n.sp. (Fig. 3 D). The thorax is grayish-light brown and three dark brown praescutal stripes can frequently be observed on its dorsal side. Brown patches can be observed on mediotergite, anepisternum, katepisternum and the base of the coxa (Fig. 5 B).

On first view the main distinguishing characteristic of P. occulta is the narrower wing with a yellowish to brownish membrane, in comparison with the wing of P. f u s c a n. sp. (Fig. 6 B). Dark-coloured spots of the wing are reduced in some individuals. The dark seam over the wing cord is longer and narrower, extending from costa to the proximal end of vein CuA2 (this seam is shorter in P. f u s c a). The halters are identical with P. f u s c a n.sp. (Fig. 5 B). The coxa and trochanter are yellowish brown. The femur is brown in the basal section, yellowish toward the tip (Fig. 2 B). The rest of the leg is brown. The abdomen is light reddish-brown, except for the two terminal segments, which are darker brown.

Male terminalia is lighter yellowish than those of P. f u s c a n. sp. and the proctiger is more lightly sclerotized (Fig. 7 B). The lobe of the gonocoxite is shorter and broader compared to the sister species; oblique, but not convex on its ventral side (Fig. 8 D). The saddle-like gonostylus is equally broad in its extent, with both ends curved upward (Fig. 8 E). The interbase has a straight collar, not oblique as in P. f u s c a n. sp., with a small lobe in the middle (Fig. 8 E). The interbase thorn is variable, frequently with a lateral orientation (character evaluated from interior view, Fig. 8 F).

The female terminalia described here is based on a specimen collected in Bitburg, Germany, close to the type locality Solingen where the original male specimens were identified. Female terminalia of P. o c c u l t a is rather similar with those of P. f u s c a n. sp. but slightly different in its generally yellowish-brown colour and the slender and longest cerci (Fig. 9 B). The infraanal plate bears less than 5–6 bristles on its subapical end (Fig. 9 D). For additional material examined, see Table 1 in the Appendix.

Distribution confirmed by the material examined. Pedicia occulta is a West Palaearctic species (Oosterbroek 2011). For the material examined see Fig. 1, Table 1.

Mitochondrial sequence support. The sequence data shows strong differences between the barcode (mtCOI) fragments of P. f u s c a n. sp. and P. occulta (Fig. 10). We found no shared haplotypes between the two species. The observed differentiation (13.1% sequence divergence) is well over the 2% sequence divergence threshold generally used for delimiting cryptic entities of aquatic insects (Zhou et al. 2010). This is high compared to their distances from the outgroup (P. straminea, 15.5% sequence divergence, for both P. f us ca n. sp. and P. occulta). The patterns of genetic differentiation are similar to those published by Ujvárosi et al. (2010a), based on a different fragment of the mtCOI gene.