Corethrella (Corethrella) ananacola Dyar, 1926

Amaral, André P., Mariano, Rodolfo & Pinho, Luiz Carlos, 2023, Description of five new species of frog-biting midges (Diptera, Corethrellidae) from Brazil and examination of new morphological characters with utility for taxonomic and phylogenetic studies, European Journal of Taxonomy 874 (1), pp. 1-120 : 50-53

Corethrella (Corethrella) ananacola Dyar, 1926

Fig. 22 ; Appendix 1

Diagnosis

Larva

Only bromeliculous species with the following combination of characters: head mostly pale ( Fig. 22D ), with darker mandibles and maxillae; postmentum elongate, with margins gently tapering from base ( Fig. 22E ); crown with about 14 spines regularly distributed, sizes slightly growing towards lateral, with two ventralmost shorter; subgenal carina without spinules ( Fig. 22E ); ventral margin of antennal groove serrate ( Fig. 22E ).

Pupa

Only bromeliculous species with following combination of characters: exuvia medium brown, abdomen elongate and tapering, darker mesially; abdominal segments little expanded laterally; one dorsal and one lateral well-developed setae on each of segments II–VII (largest setae not longer than 1.67 times length of segment); dorsal setae progressively shorter from V–VII; all setae lightly pigmented; respiratory organ tubular, elongate, expanded at apex.

Material examined

BRAZIL – Santa Catarina State • 1 ♀, adult, with pupal and larval exuviae; Santo Amaro da Imperatriz, Plaza Caldas ; 27°44ʹ01ʺ S, 48°48ʹ45ʺ W; 248 m a.s.l.; 22 Jul. 2014; L.C. Pinho et al. leg.; bromeliad; CE-MHS • 2 ♀♀, 1 ♂, adults, with pupal exuviae; same collection data as for preceding; CE-MHS • 2 ♂♂, adults, with pupal exuviae; same collection data as for preceding, except 7 Jun. 2014; CE-MHS .

Description

Male and female adults (3 ♂♂, 3 ♀♀)

HEAD. Sensilla ( Fig. 22A ): Ocular row with 1 thick offset seta at ventral part, 1 more dorsal and 13–15 extending to mid-posterior portion of head. Subocular row not well-defined anteriorly, with about 5 setae on posterior portion. Interocular space and vertex with many slender setae. Postgenal row with 9–13 slender setae, ranging from posterior part of ocular row to subventrally. With 2 thick ventromedial setae.

THORAX. Sensilla ( Fig. 22B ): Antepronotum with 1–3 slender dorsal setae and about 4–10 intermediate/ slender ventral setae. Postpronotum with 1 thick and 1 slender dorsal setae; 1 intermediate and 4–5 slender posterior setae. Scutum, prescutal area with 2–3 thick, vertically aligned, posterior setae; 7–9 thick/intermediate and 11–15 slender setae spread. Antealar area with 3–4 thick/intermediate setae vertically aligned anteriorly and 8–10 thick/intermediate setae more posteriorly; about 15–26 slender setae distributed from ventral to dorsal portions. Supraalar area with 3–4 thick setae surrounded by about 6–15 slender setae. Dorsocentral row, posterior part with cluster of 4–5 thick and 6 slender setae; 16–20 thick/intermediate and approximately 27–45 slender setae filling row. Scutellum with 8–10 thick setae. Posterior anepisternum bare. Anepimeron with 3–12 slender mid-posterior setae.

WING. Male R 3 /R 1: 0.44 (0.43–0.46); R 2+3 /R 2: 0.79 (0.77–0.81). Female R 3 /R 1: 0.49 (0.48–0.49); R 2+3 /R 2: 0.78 (0.73–0.86).

LEGS. Empodium ( Fig. 22C ) of intermediate length, intermediate thickness, with 3 branches. Male Ta1/Ta2: 3.06 (3.00–3.13); Ta3/Ta4: 0.68 (0.64–0.73). Female Ta1/Ta2: 2.79 (2.67–2.88); Ta3/Ta4: 1.13 (1.09–1.20).

Larva (n = 1)

EXUVIA ( Fig. 22D ). Head mostly pale; mandible and maxilla more darkly pigmented; thorax and abdomen unknown.

HEAD ( Fig. 22E ). Wide, somewhat round in dorsoventral view, 1.18 times as wide as long.Antenna 0.46 times length of head; antennal groove 1.23 times length of antenna. Ventral margin of antennal groove serrate. Postmentum elongate, with margins gently tapering from base; 0.90 times as wide as long; head 0.55 mm long. Prementum curved, with 13 apically tapering, darkly pigmented teeth, central one largest, second small, third large and remaining ones gradually smaller.Anteroventral projection of gena strongly projected anteriorly, surface smooth. Postcoila extending to lateral margin of gena. Subgenal carina without spinules. Crown with 14 spines, regularly distributed, sizes slightly growing towards lateral, with first two ventral ones shortest; largest spine 0.07 mm long. Seta 16-C anterolateral to crown. Mandible, apical tooth length 1.29 of first dorsal tooth; seta 3-Mn 0.46 length of 4-Mn; lacinia mobilis with 7 blades; mandibular lobe well-developed, pale, contiguous to teeth. Sensilla: 9-C short, fan-like; 10-C elongate, simple; 11-C moderately elongate, simple; 12-C elongate, simple; 13-C short, fan-like; 14-C moderately elongate, simple; 15-C elongate, forked; 16-C elongate, simple. 0a-Mn unknown; 0b-Mn elongate, simple. 6-Mx short, simple; 4-Mx moderately elongate, simple; 5-Mx short, simple.

SIPHON. Unknown.

Pupa (n = 6)

EXUVIA ( Fig. 22F ). Medium brown, with mesial portion of abdominal segments III–VII darker; all setae lightly pigmented.

CEPHALOTHORAX. Length 1.29 mm (1.24–1.37). Respiratory organ ( Fig. 22G ) tubular, elongate, with expanded apical opening; trachea not spiraled, 0.24 mm (0.23–0.26) long. Dorsal seta 1 pale, short, thick; one length apart from dorsal 2; dorsal 2 pale, of same basal thickness, tapering distally, about four times as long; both setae arising from undifferentiated cuticle. Metathoracic 2 and supraalar 2 sensilla present. Metathoracic seta 1 short, fan-like.

ABDOMEN ( Fig. 22H ). Elongate, tapering, tegument smooth. Segments I–VIII length 1.38 mm (1.17– 1.51), width/length: 0.54 (0.51–0.58). Margins serrate, little expanded laterally. Setae D-2 elongate, subequal from II–IV. Lateral setae well-developed on II–VII. Largest seta D-2-III, 1.42 (1.22–1.67) length of segment. Terminal process elongate, basal width 0.65 (0.61–0.69) of length, paddles moderately broad, with small indentation on mesial margin; D-1-IX short, at about 0.70 from base; apical spine articulated; ventroapical seta V-1-IX about 3 times as long as apical spine; male and female genital lobes ovate, in male slightly extending beyond basal portion. Chaetotaxy as illustrated.

Distribution and biology

The specimens were previously recorded by Amaral et al. (2019). They were collected in Atlantic forest fragments in Santa Catarina State, at altitudes ranging from 13 to 252 m a.s.l. Immatures were captured from bromeliad tanks and two adults in CDC traps.

This species is otherwise known from Costa Rica, Panama, Trinidad and Tobago, and the Brazilian states of ES and SP, at altitudes ranging from 0 to 600 m a.s.l. ( Borkent 2008).

Remarks

Immatures of Corethrella ananacola have previously been described by Dyar (1926), Lane (1939b, 1942, 1953), and Borkent (2008). There was only one larval exuvia available, and it lacked the thorax and abdomen. Nevertheless, the morphologies of larval head and the pupa are similar to those of C. borkenti , which is currently hypothesized to be phylogenetically distant. In future analyses, including immature morphology and molecular data, a closer relationship between these species may be retrieved.

Figures

Fig. 22. Corethrella ananacola Dyar, 1926. A. Adult cranial setae, anterior and posterior views, and female clypeus in anterior view. B. Adult thoracic setae, lateral view. C. Hind leg claw and empodium, lateral view. D. Head of larval exuvia, ventral view. E. Exuvia of larval head, ventral view, except mandible in dorsal view. F. Pupal exuvia, dorsal view. G. Pupal respiratory organ, dorsal view. H. Pupal methatorax and abdomen, dorsal and ventral views. Scale bars: 0.2 mm. Abbreviations: D-1–9 = dorsal setae; L-1–4 = lareral setae; V-1, 5–6 = ventral setae.