Tachytrechus costaricensis Brooks

Brooks, Scott E. & Cumming, Jeffrey M., 2008, The Tachytrechus alatus species group (= Syntomoneurum Becker) revisited: new species and revised species group limits (Diptera: Dolichopodidae), Zootaxa 1676, pp. 1-27 : 8-11

publication ID	https://doi.org/ 10.5281/zenodo.180314
DOI	https://doi.org/10.5281/zenodo.6227303
persistent identifier	https://treatment.plazi.org/id/03D787A6-FFA6-FF99-E1C9-6696FFFAFA76
treatment provided by	Plazi
scientific name	Tachytrechus costaricensis Brooks
status	sp. nov.

Treatment

Tachytrechus costaricensis Brooks View in CoL sp. nov.

(Figs. 3, 4, 12)

Diagnosis. Upper part of face metallic greenish or bluish, lower part of face and clypeus silvery; 2 notopleural bristles; R4+5 and M subparallel in distal portion (Figs. 3C, 3D), male wing membrane unevenly infuscated and lacking costal swelling (Fig. 3C); tibiae and tarsi mainly dark; male fore tibia slightly swollen apically with silvery anterodorsal patch, male fore tarsomeres 2 and 3 enlarged with anterior surface bare and silvery (Fig. 3E); tarsomere 2 of midleg longer than basitarsus; hypandrium with elongate ventral projection and lamellate subapical process on right side ( Figs. 4 View FIGURE 4 A, 4B).

Description. Male: Body length: 6.8–7.0 mm, wing length: 6.2–6.4 mm.

Head (Fig. 3A): Vertex distinctly excavated, vertical bristle weak and short, less than half as long as paravertical bristle, subequal to upper postocular seta, pair of strong ocellar bristles, pair of strong paravertical bristles. Postoculars mainly white, becoming stronger ventrally, upper five postoculars black, short. Frons dark metallic green with bronze reflections. Upper part of face metallic blue with bronze reflections, weakly metallic green medially, lower part of face and clypeus silvery, clypeus broadly rounded below. Palpus brown with pale yellow margin, ground color obscured by silvery pruinosity at certain angles, with pale hairs, with or without distinct apical seta. Antenna: Scape subtriangular in lateral view, laterally compressed, blackish dorsally, brownish ventrally, about 0.7x as long as pedicel and postpedicel combined; pedicel blackish; postpedicel mainly blackish, ovoid, about 1.6x as long as wide; arista-like stylus subapical, black with white apex, about 3.6x as long as postpedicel, basal article about 0.1x as long as distal article. Thorax: Notum metallic greenish-blue with coppery reflections, with metallic blue-violet vitta lateral to acrostichals, with grayish pruinosity anteriorly, lateral margin mainly dark bronze; acrostichals biserial, 6 dorsocentrals, 1 presutural, 1 sutural, 2 supraalars, 1 postalar, 1 posthumeral, 1 postpronotal bristle with 1–2 weaker setae, 2 notopleural bristles, posterior bristle weak. Pleuron with silvery pruinosity, metaepisternum bare. Scutellum greenish-blue with coppery reflections, with strong inner bristle and weak outer seta. Legs: Fore coxa yellow, mid coxa mainly dark with pale apex, with silvery pruinosity, hind coxa mainly dark on outer surface with silvery pruinosity, anterior surface pale; femora dark metallic greenish or blackish dorsally, yellow ventrally; tibiae mainly dark brown or dark metallic green, paler ventrally; tarsi dark, fore tarsus with tarsomeres 2–3 modified (see below). Foreleg: Coxa with pale pile and weak setae, silvery-white at certain angles, apical margin with 2 strong outer and 4–5 weak inner setae; femur with distinct tubercle behind basal cluster of 2 strong bristles, posterior preapical seta present; tibia with 1–2 anterodorsal setae, 1–2 posterodorsals, 2 apicals, apex swollen with silvery anterodorsal patch; tarsus slightly longer than tibia, tarsomeres 2 and 3 enlarged with anterior surface bare and silvery (Fig. 3E), tarsomere 2 with anterodorsal row of curved setae, tarsomere ratio: 4.1/3.1/ 2.0/1.1/1.0. Midleg: Coxa with row of 2–3 weak black setae medial to cluster of 3 strong bristles; femur with distinct tubercle on ventral surface proximal to mid-length, 1 strong anterior preapical bristle, tibia with 3–4 anterodorsal setae, 3 posterodorsals, 3 ventrals, 4 apicals; tarsus 1.5x longer than tibia, tarsomere ratio: 6.2/ 7.8/2.1/1.0/1.4. Hindleg: Femur with 1 strong anterodorsal preapical bristle; tibia with 4 anterodorsal setae, 2– 3 posterodorsals, 5–7 ventrals, 1 preapical dorsal, 2 apicals, with dentiform posteroapical process; tarsus about 1.3x longer than tibia, with hook-shaped posterobasal process opposite apical dentiform process of tibia, tarsomere ratio: 4.4/9.1/2.5/1.0/1.3. Wing (Fig. 3C): Veins dark brown, membrane unevenly infuscated; costa unmodified, without costal swelling; M with S-shaped bend; R4+5 and M subparallel in distal part; crossvein dm-cu near midpoint of wing, longer than distal section of CuA1. Calypter with black setae. Abdomen: Tergites 1–5 metallic green with coppery reflections, with silvery pruinosity laterally, posterior margin of tergites dark brown; tergite 5 with large posterior membranous region, extended laterally as broad band to ventral margin of sclerite; sternite 5 with eversible glandular structure; tergite 6 blackish with metallic green reflections; segment 7 dark brown; sternite 8 subtriangular with several long setae near posterior margin, largely covered with silvery pruinosity, dull metallic blue basally. Hypopygium ( Figs. 4 View FIGURE 4 A, 4B): Epandrium black with FIGURE 3. Tachytrechus costaricensis Brooks sp. nov.: (A) male head; (B) female head; (C) male wing; (D) female wing; (E) male foretarsus (anterior view). Abbreviations: A1: anal vein; CuA1: 1st anterior branch of cubital vein; dm-cu: discal medial-cubital crossvein; M: medial vein; pavt s: paravertical seta; R1: 1st radial vein; R2+3: 2nd + 3rd radial vein; metallic green-blue reflections; basiventral epandrial lobe elongate, digitiform, pointed apically, with basiventral protuberance, seta present, near base of lobe; apicoventral epandrial lobe short, projected posteriorly, ventral margin rounded, posterodorsal margin truncate, with pair of pale setae, medial seta branched apically; accessory epandrial process present medial to apicoventral epandrial lobe. Surstylus ( Fig. 4 View FIGURE 4 C): Ventral lobe digitiform, slightly flattened dorsoventrally, with ridged ventral surface, apex with blunt curved seta; dorsal lobe about half as long as ventral lobe, flared apically, apex with setae laterally and rugose membraneous portion medially. Apicolateral arm of postgonite ( Figs. 4 View FIGURE 4 C, 4D) lacking medial process, apex expanded and granulated. Cercus pale yellow with dark apical margin, subquadrate in dorsal view, lateral margin with long setae. Hypandrium with lamellate lateroventral process subapically on right side and elongate claw-like projection ventrally ( Figs. 4 View FIGURE 4 A, 4B). Phallus simple, tubular in distal part, widened in middle section with acute dorsal projection ( Fig. 4 View FIGURE 4 A).

Female: Body length: 6.6–6.8 mm, wing length: 6.0– 6.6 mm. Similar to male except as follows: Head: Vertical bristle stronger, subequal to paravertical (Fig. 3B); upper part of face dull metallic green-bronze; clypeus acutely rounded below (Fig. 3B); tip of stylus whitish, but not as pronounced as in male. Thorax: Metaepisternum sometimes with 1 weak hair. Legs: Foreleg: Femur lacking ventral tubercle and associated cluster of bristles; tibia with 2–4 anterodorsal setae, sometimes with 1–2 weak posterior setae, apex only slightly enlarged, lacking silvery anterodorsal patch; tarsomeres 2 and 3 unmodified, dark, tarsomere 2 lacking curved setae anterodorsally. Midleg: Setation of coxa similar to male but weaker; femur lacking ventral tubercle. Hindleg: Tibia lacking dentiform posteroapical process; tarsus lacking hook-shaped posterobasal process. Wing (Fig. 3D): Membrane evenly infuscated, brownish. Abdomen: Tergites 1–5 subrectangular, metallic green with coppery and violet reflections, with silvery pruinosity laterally, posterior margin of tergites dark; sternites brownish-black, tergite 1 very short, band-like, tergites 2–5 subrectangular; tergites 6 and 7 wider than long, divided medially into subquadrate halves, sternites 6 and 7 smaller, undivided, sternite 7 broadly V-shaped; tergite 8 divided medially, narrowly connected to sternite 8 anterolaterally, sternite 8 undivided, lacking deep medial invagination; tergite 10 divided into subtriangular hemitergites, each with 3–5 spines.

Type material. Holotype ɗ, COSTA RICA: Guanacaste, Estación Maritza, west side of Volcan Orosi, II curso Parataxonomos, August 1990, L-N-326900, 373000, INBIO CRI 000 253845 ( INBC). Paratypes, 1ɗ with same data as holotype; 1ɗ and 7Ψ, COSTA RICA: Alajuela, Rio San Lorencito, 900 m, R.F. San Ramón, 5 km N of Colonia Palmareña, 13–18.vi.1993, I curso Scarabaeidae , L-N-244500, 470700 ( INBC).

Distribution. Tachytrechus costaricensis is known from the type locality near Volcan Orosi, Guanacaste, and from Alajuela, along the Rio San Lorencito, Costa Rica ( Fig. 12 View FIGURE 12 ).

Etymology. The new species name is derived from the country of the type locality.

Remarks. The holotype male and the two male paratypes are quite badly damaged.