Corethrella alticola Lane, 1939a

Amaral, André P. & Pinho, Luiz Carlos, 2015, New species and records of frog-biting midges from southern Brazil (Diptera: Corethrellidae), Zootaxa 3946 (2), pp. 274-284 : 281-283

Corethrella alticola Lane, 1939a

( Figures 22–28 )

Additional material. Seven females, five males, BRAZIL: Santa Catarina State, Grão Pará, Serra Furada State Park, CAPEA stream, 28°11’26” S 49°23’30” W, 510m a.s.l., 06.ix.2012 – 15.x.2012, malaise, LC Pinho, AC Ganzer, LS Gomes & AG Parise leg. One male as previous except 17.xi.2012, reared from larva, LC Pinho, & LC Gomes & AL Schlindwein leg. Three females, one male as previous except 07.v.2013, LC Pinho, & V Freitas leg. Two females as previous except 07.iv.2013, LC Pinho, AL Schlindwein & AP Amaral leg. Fourteen females, fifteen males as previous except 16.xi.2012 – 07.i.2013, malaise, LC Pinho, MC Novaes & MF Haddad leg. One female, BRAZIL: Santa Catarina State, Grão Pará, Serra Furada State Park, 28°11’28” S 49°23’30” W, 505m a.s.l., 13.x.2012, Frog call trap ( Physalaemus cuvieri calling), LC Pinho, AC Ganzer, LS Gomes & AG Parise leg. Forty females, twenty seven males, BRAZIL: Santa Catarina State, Grão Pará, Serra Furada State Park, 28°10’36” S 49°23’41” W, 622m a.s.l., 14.x–16.xi.2012, malaise, LC Pinho, LS Gomes & AL Schlindwein leg. Thirty eight females, six males, BRAZIL: Santa Catarina State, Grão Pará, Serra Furada State Park, 28°10’27” S 49°23’38” W, 652m a.s.l., 17.xi.2012, Shannon trap, LC Pinho, LS Gomes & AL Schlindwein leg. One female, BRAZIL: Santa Catarina State, Orleans, Brusque do Sul, Rio Minador, 28°14’32” S 49°24’13” W, 236m a.s.l., 07.i.2013, light trap, LC Pinho, MC Novaes & MF Haddad leg. One male, BRAZIL: Santa Catarina State, Orleans, Rio Minador, 28°10’43” S 49°24’33” W, 447m a.s.l. 8.vi.2013, reared from larva, LC Pinho, AP Amaral, MO Bessel & AM Will leg. One male, BRAZIL: Santa Catarina state, Porto Belo, Araçá Environmental Protection Area, Brejo Guinho, S 27°07’21” W 48°30’51”, 81m a.s.l., 27.viii.2011, AC Ganzer & N Fabris leg.

Diagnostic characters. The pupa of C. alticola can be distinguished from other pupae within the peruviana group by the combination of the following characters: abdomen slightly darker and rough on margins, segments 3– 7 moderately expanded laterally with L-4 setae much shorter than corresponding segment length. The larva differs from C. blanda and C. davisi in having at least 14 teeth on the mentum. Also, larvae differ from those of C. davisi in having the siphon about three times longer than wide.

Descriptions. Pupa (n=7). Total length 2.66–2.93 mm. Third abdominal segment 0.84-0.98 mm wide. Exuviae ( Fig. 22 ) mostly yellowish. Abdominal margins slightly darker, rough, serrate.

Cephalothorax. Metathorax without spherical sensory pits. Respiratory organ ( Fig. 23 ) trilobed, broadly flattened, about 1.5 times wider than long with spiracles along outer margin; anterior lobe elongate, lateral lobe elongate, as wide as the anterior; deep concavity between lateral, posterior lobes. Posterior lobe moderately wide.

Abdomen ( Fig. 24 ). Chaetotaxy as in figure 24. All sensilla very short. Segments expanded laterally with sharp extremities. Terminal process 0.43–0.49 mm long, serrate on margins, with spined apex, mesial seta on lateral margin.

Larva (n=6–7). Coloration greyish dark brown, with darker sclerotized plates on thorax and abdomen.

Head ( Fig. 26 ). Length 0.83–0.86 mm and width 0.88–0.98 mm. Antennae 0.45–0.50 mm long, about 0.6 times length of head, inserted apically on head, bearing three stout apical spines, one longer than others, about 0.5 times length of shaft. Mandible ( Fig. 25 ), with two dorsal teeth, one large apical tooth, five short inner teeth. Mandibular lobe rounded, as dark as teeth. Outer margin serrate with two thick setae located apically, very short one at center, right beside long one; basally brush with seven stout, serrate spiniform setae. Mentum ( Fig. 27 ) with 14–17 bold teeth, lateral ones gradually shorter. Posterolateral row of 14–15 spines, of which 7–8 located dorsally, 6–8 ventrally.

Body. Damaged, chaetotaxy not described. Anal segment cylindrical, about 1.5 times longer than wide. Siphon cylindrical ( Fig. 28 ) 382–441 µm long, 99–147 µm wide, with pair of slender subapical setae, spiracular plate with two pairs of thick setae, another pair of slender ones.

Distribution and bionomics. Corethrella alticola was previously known only from the Brazilian states of São Paulo and Goiás at altitudes ranging from 834–1736 m ( Borkent, 2008). Its current distribution is now extended to south Brazil, at northern and southern Santa Catarina state at altitudes ranging from 80– 500 m. Larvae were collected in streamside pools and the adults caught in malaise traps, light traps and frog call traps playing the call of Physalemus cuvieri Fitzinger, 1826 .

Taxonomic discussion. Corethrella alticola belongs to the peruviana species group, recognized, among other synapomorphies, by a very broad and flattened pupal respiratory organ and a terminal process without socketed spines ( Borkent, 2008). Twelve species are assigned to the peruviana group and pupae are known for five of these: C. manaosensis ( Lane & Cerqueira, 1958) , C. inornata Borkent, 2008 , C. pallida Lane, 1942 , C. blanda Dyar, 1928 and C. davisi Shannon & Del Ponte, 1928 . Pupae of Corethrella alticola differ from those of C. inornata by having a relatively long terminal process and abdominal segments 3–7 with short lateral setae. This last character and the shallow concavity between anterior and lateral lobes of respiratory organ also distinguishes C. alticola from C. blanda and C. pallida (as described by Borkent, 2008).

Corethrella alticola is easily distinguished from C. davisi by the abdominal segments (expanded in C. alticola and not expanded in C. davisi ) and shape of the respiratory organ (anterior lobe relatively short, posterior lobe subtriangular in C. alticola and anterior lobe relatively long, posterior lobe large and rounded in C. davisi ). Larvae have been previously described for only two species of the peruviana group, C. blanda and C. davisi . However, descriptions of larvae within the genus are mostly incomplete and therefore it is not possible to understand the differences between most species at present.

Figures

FIGURES 22 – 28. Corethrella alticola Lane, 1939, pupa (22 – 24) and larva (25 – 28). 22. Pupal exuviae, dorsal view. 23. Left respiratory organ. 24. Metathorax and abdomen, tergites to the left, sternites to the right. 25. Right mandible, dorsal view. 26. Larval head capsule, ventral view. 27. Mentum. 28. Siphon, lateral view.