Corethrella (Corethrella) borkenti Amaral & Pinho, 2015

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 : 82-85

Corethrella (Corethrella) borkenti Amaral & Pinho, 2015

Fig. 41 ; Appendix 1

Diagnosis

Larva

Only bromeliculous species with the following combination of characters: head mostly pale, but mandible, maxilla, segment X, and siphon more darkly pigmented ( Amaral & Pinho 2015: fig. 19); postmentum elongate, with margins almost parallel up to basal 0.6, strongly tapering distally ( Fig. 41D ); prementum with 12–14 darkly pigmented teeth ( Fig. 41D ); central tooth large, second small, third large and remaining ones gradually decreasing in size ( Fig. 41D ); seta 15-C bifurcated or forked.

Pupa

Only bromeliculous species with the following combination of characters: exuvia medium brown ( Amaral & Pinho 2015: fig. 16), abdomen elongate and tapering, darker mesially; abdominal segments little expanded laterally, with one dorsal and one lateral well-developed setae ( Amaral & Pinho 2015: fig. 18) on each of segments II–VII (these setae longer than respective segments, largest ones about twice as long); dorsal setae progressively shorter from V–VII; all setae darkly pigmented; respiratory organ tubular, very elongate, expanded at apex ( Amaral & Pinho 2015: fig. 17).

Material examined

BRAZIL – Bahia State • 1 ♂, adult; Ilhéus, UESC Max de Menezes ; 14°47ʹ54ʺ S, 39°10ʹ24ʺ W; 21 May 2019; A.P. Amaral leg.; Mirco’s bromeliad; CE-MHS • 1 ♀, adult, with larval and pupal exuviae; Ilhéus, Cabruca da UESC ; 14°47ʹ48ʺ S, 39°10ʹ20ʺ W; 35 m a.s.l.; 16 May 2019; A.P. Amaral leg.; bromeliad; CE-MHS • 1 ♀, adult, with larval and pupal exuviae; Porto Seguro, RPPN Estação Veracel , Trilha 12-09; 16°19ʹ38ʺ S, 39°07ʹ22ʺ W; 73 m a.s.l.; 28 Aug. 2019; A.P. Amaral leg.; bromeliad; CE-MHS . – Santa Catarina State • 1 ♀, adult; Grão Pará, Parque Estadual Serra Furada , CAPEA stream; 28°11ʹ26ʺ S, 49°23ʹ30ʺ W; 16 Nov. 2012 – 7 Jan. 2013; L.C. Pinho, M.C. Novaes and M.F. Haddad leg.; Malaise trap; CE-MHS • 1 ♀, adult, with larval and pupal exuviae; Florianópolis, Pantanal, Rua Sulcar ; 27°36ʹ35ʺ S, 48°30ʹ57ʺ W; 53 m a.s.l.; 21 Jul. 2016; A.P. Amaral leg.; bromeliad; CE-MHS .

Description

Male and female adults (1 ♂, 4 ♀♀)

HEAD. Sensilla ( Fig. 41A ): Ocular row with 1 thick offset seta at ventral part and 1 more dorsally, followed by 13–15 setae shortly extending posteriorly. Subocular row well-defined with about 20 slender setae from interocular space to posterior portion. Vertex with a few scattered setae. Postgenal row with 6–15 slender setae, ranging from mid-posterior portion of head to ventromedially. With 2 thick ventromedial setae.

THORAX. Sensilla ( Fig. 41B ): Antepronotum with 1–2 dorsal and 3–7 anteroventral intermediate setae. Postpronotum with 1 thick dorsal, 1 slender anterodorsal, and 4–5 more ventrally located setae. Scutum, prescutal area with 2 thick and 2–4 intermediate setae, dorsoventrally aligned near prescutal suture; 0–7 intermediate/slender anterior setae. Antealar area with cluster of about 5–7 thick, 4–8 intermediate, and 6–9 slender setae located ventrally; 11–25 slender dorsal setae. Supraalar area with 3–4 thick and 0–1 intermediate setae aligned longitudinally, about 6–9 slender setae surrounding. Dorsocentral row, posterior part with cluster of 4–6 thick and about 3–7 slender setae; approximately 17–23 thick/ intermediate and 38–41 slender filling row. Scutellum with 12–14 thick setae. Posterior anepisternum bare. Anepimeron with 5–17 slender setae.

WING. Male R 3 /R 1: 0.40; R 2+3 /R 2: 0.94. Female R 3 /R 1: 0.51 (0.47–0.55); R 2+3 /R 2: 0.66 (0.59–0.73).

LEGS. Empodium ( Fig. 41C ) of intermediate length and thickness, with 5 branches. Male Ta1/Ta2: 3.00; Ta3/Ta4: 1.60. Female Ta1/Ta2: 2.90 (2.71–3.00); Ta3/Ta4: 1.09 (1.08–1.13).

Larva (n = 3)

EXUVIA ( Amaral & Pinho 2015: fig. 19). Head mostly pale; mandible, maxilla, segment X, and siphon more darkly pigmented; without tergal plates.

HEAD ( Fig. 41D ). Wide, somewhat round in dorsoventral view, 1.22 (1.19–1.25) times as wide as long. Antenna 0.41 (0.40–0.41) times length of head; antennal groove 1.36 (1.25–1.48) times length of antenna. Ventral margin of antennal groove serrate. Postmentum elongate, with margins almost parallel until basal 0.6, strongly tapering distally; 1.13 (1.11–1.14) times as wide as long; length 0.58 (0.57–0.59) of head. Prementum ( Amaral & Pinho 2015: figs 21–22) curved, with 12–14 darkly pigmented teeth; central tooth largest, second tooth small, third large, 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 13–17 regularly distributed spines, sizes growing towards lateral, ventral spines shortest; largest spine 0.08 mm (0.07–0.09) long. Seta 16-C anterolateral to crown. Mandible, apical tooth 1.62 (1.43–1.83) times length of first dorsal tooth; seta 3-Mn 0.43 (0.42–0.43) times length of 4-Mn; lacinia mobilis with 8 blades; mandibular lobe well-developed, pale, contiguous to teeth. Sensilla: 9-C short, fan-like; 10-C elongate, simple; 11-C elongate, simple or forked; 12-C elongate, simple; 13-C short, fan-like; 14-C moderately elongate, simple; 15-C moderately elongate, bifurcated or forked; 16-C elongate, bifurcated. 0a-Mn short, fan-like; 0b-Mn elongate, simple. 6-Mx short, bifurcated; 4-Mx moderately elongate, simple; 5-Mx short, fan-like.

SIPHON ( Amaral & Pinho 2015: fig. 28). 0.32 mm (0.30–0.34) long. Seta 1 forked, situated at 0.19 (0.11–0.26) of length from base; 6-S pale, 9-S darkly pigmented; length of 6-S/9-S: 0.54 (0.48–0.60).

Pupa (n = 3)

EXUVIA ( Amaral & Pinho 2015: fig. 16). Medium brown, with abdominal segments II–VII darker mesially; setae darkly pigmented, except cephalothorax dorsal 1, setae on terminal process lightly pigmented.

CEPHALOTHORAX. Length 1.32 mm (1.17–1.61). Dorsal seta 1 pale, short, moderately thick; about one length apart from dorsal 2; dorsal 2 darkly pigmented, of same basal thickness, about four times as long; both setae arising from undifferentiated cuticle. Metathoracic 2 and supraalar 2 sensilla present. Metathoracic seta 1 short, simple.

ABDOMEN ( Amaral & Pinho 2015: fig. 18). Elongate, tapering from IV–VII, dorsal tegument smooth; length of segments I–VIII: 1.37 mm (1.17–1.73), width/length: 0.54 (0.49–0.58). Margins serrate, moderately expanded laterally, somewhat posteriorly from VI–VIII. Largest seta L-2-II, 1.79 (1.68– 1.94) times length of segment. Terminal process moderately elongate, basal width 0.70 (0.67–0.72) of length, with paddles moderately tapering from base; D-1-IX short, at about 0.50 from base; apical spine articulated; ventroapical seta V-1-IX about 3 times as long as apical spine; female genital lobe tapered at midlength, distinctly narrower than base of paddles; genital lobe elongate in male, slightly tapering, extending to half length of paddles. Chaetotaxy as illustrated.

Distribution and biology

Examined individuals with their associated exuviae were collected as larvae from bromeliads in the Atlantic forest of Santa Catarina and Bahia states. Adults were collected with light traps ( Amaral et al. 2019). This species has been recorded at altitudes ranging from 35 to 248 m a.s.l.

Remarks

In the original description, Amaral & Pinho (2015) recognized as a diagnostic feature of the species the exceptionally elongate pupal respiratory organ, with a length 13–18 times its basal width. The specimens examined here show a less elongated respiratory organ, with a length/width ratio ranging from 9.5 to 13. The other diagnostic features of immatures and adults, however, made it possible to confidently identify the specimens. Moreover, in the original description, the long lateral seta on the abdomen of the pupa is indicated as L-4, but we here reinterpret it as an L-2 seta. One of the specimens seems to have trifid branches on the empodium, although the position of the legs on the microscope slide make it difficult to confirm this.

Figures

Fig. 41. Corethrella borkenti Amaral & Pinho, 2015. 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. Exuvia of larval head, ventral view, except mandible in dorsal view. Abbreviations: ocs = ocular row of setae; pgs = postgenal row of setae; pot = postcoila; sos = subocular row of setae; vms = ventromedial setae.