Stegana (Steganina) tempifera Malloch, 1924

Bächli, Gerhard & Vilela, Carlos R., 2022, On the identities of Neotropical Stegana species (Diptera, Drosophilidae). III. Four Costa Rican species described by J. R. Malloch, Revista Brasileira de Entomologia (e 20210113) 66 (1), pp. 1-23 : 17-22

Stegana (Steganina) tempifera Malloch, 1924

( Figs. 26–31 )

Stegana tempifera Malloch, 1924a: 98 (key, description), Malloch, 1924b: 3 (description); Heed, 1956: 61 (distribution); Heed, 1957: 76 (distribution); Wheeler, 1970: 79.7 (affiliation).

Stegana (Steganina) tempifera Malloch : Wheeler, 1981:31 (affiliation); Brake and Bächli, 2008: 300 (affiliation).

Type locality: Costa Rica, Province of Alajuela, Canton of San Mateo, Higuito.

Diagnosis. Generally brownish flies.Front pale with one large upper and one smaller lower black, medially joining triangles that form an hourglass-shaped design. Pleura pale with two distinct black bands. Surstylus trapezoid, bearing two blunt prensisetae (one dorsal and one ventral), double-walled, inner wall densely covered in the anteromedial area with ca. 40 strong, curved, and sharp-tipped setae. Dorsal arch sclerotized, laterally perpendicular and widely fused to the posterior hypandrium arms, dorsodistally strongly projected forward as a half pear-shaped tube dorsally sheltering the aedeagus. Gonopods proximally fused to each other, with each side apparently bearing one tiny setula on a conspicuous conical-shaped tip. Aedeagus ca. 1/2 length of the aedeagal apodeme, distally covered with seta-like scales, anterior ones short and posteromarginal ones conspicuously long, sharply pointed, distally 3- or 4-branched (longest ones), and fringe-shaped; base of aedeagus linked to the aedeagal apodeme by membranous tissue.

Material examined (n = 6).

Holotype ♂ [#23], dissected, labeled ( Fig. 26 ): “Higuito / SanMateoCR [ Costa Rica] // PabloSchild / coll // Stegana / tempifera / Type [handwritten] / Det. / J R Malloch [printed] // Type No. / 26680 [handwritten] / U.S.N.M. [red label] // USNMENT / [QR code] / 01384614 [back side] // Stegana / tempifera Malloch / Bächli & Vilela det. 2017 // HOLOTYPE [red label] // ♂ ”. Paratypes: ♂♂ [#31, #32], ♀♀ [#29, #30]: same data as holotype, except Type status and QR code labels. Non-type specimen ♀ [#33]: labeled: “… // Stegana / tempifera / Mall // ALMelander / collection / 1961 [green right half] // USNMENT [QR code] / …. [back side] // [#33].

Comments. Malloch (1924b) listed one male holotype and four paratypes. Indeed, the type specimen series we have received contains five specimens (3 ♂♂ [holotype and 2 paratypes] plus 2 ♀♀ paratypes).

The external description is based on the five type specimens and one non-type specimen (#33).

Redescription

♂. (n = 3). Head generally yellowish.Frons( Figs.27a,c , 28a ) glossy, with a large brownish spot just above the antenna, medially connected with the brownish frontal triangle, somewhat looking like an hourglass ( Fig.28a ). Frontal length 0.41 (0.39–0.43) mm.Frontal index about 1.68 (1.61–1.75), top to bottom width ratio about 1.44 (1.39–1.50).Frontal triangle apically pointed,about 50%of the frontal length; ocellar triangle prominent, black, about 45% of the frontal length. Orbital plates slightly paler, about 60% of the frontal length. Orbital setae arranged in a row, distance of or3 to or2 about 55% of or3 to or1, distance of or2 to or1 about 45% of or3 to or1, distance of or3 to or1 about 220% of or3 to vtm, or1 / or3 ratio about 1.27 (1.25–1.29), or2 / or1 ratio about 0.67 (0.61–0.73), vt index about 0.92 (0.78–1.07), postocellar setae about 35 (32–37) % of frontal the length, ocellar setae about 61 (57–63) % of the frontal length; vibrissal index about 0.25. Face brownish, with a yellowish median cross–band. Carina narrow, about 1/4 the face length. Cheek pale yellowish, narrow, index about 13 (12–13). Eye roundish, main axis almost vertical, index about1.08 (1.06–1.11).Pedicel yellow, with a dark spot above.Flagellomere 1yellow,with brownish margin,length to width ratio about 1.92 (1.75–2.14). Arista has 7 dorsal, 5–6 ventral and about 6 small inner branches, plus a terminal fork. Proboscis yellowish, palpus blackish.

Thorax ( Fig.27 ) length about 1.45 (1.42–1.50) mm. Scutum brownish, frontal margin paler, about 8 rows of acrostichal setae. Transverse distance of the dorsocentral setae six times the longitudinal distance; dc index about 0.47 (0.45–0.48). Scutellum slightly pointed apically, scut index about 1.52 (1.48–1.57), distance between the apical scutellars about 80% of the apical to the basal one; basal ones divergent. Pleura ( Fig.27b ) pale yellowish, with a black stripe in the upper 1/3 and a dark brown stripe in the upper 1/3 of the katepisternum, the stripe reaching the base of the abdomen, sterno index about 0.86 (0.82–0.90). Haltere yellow, legs generally yellowish, fe1 basally and apically brownish, ti1 with a median brownish ring, mid and hind legs with fe2 and fe3 predominantly brownish, ti2 and ti3 with dark median bands.

Wing ( Fig. 28c ) apically pointed, generally brownish, with paler hind margin, m 3 almost straight but slightly bent upwards towards the tip, both crossveins shadowed, length = 2.38 (2.17–2.52) mm, length to width ratio about 2.05 (1.97–2.18). Indices: C = 1.96 (1.81–2.18), ac about 9 (8–10), hb = 0.73 (0.71–0.76), 4C = 1.23 (1.06–1.38), 4v = 1.78 (1.63–2.00), 5x = 0.97 (0.78–1.13), M = 0.50 (0.44–0.54), prox. x = 0.92 (0.81–1.08).

Abdomen ( Fig. 27b,d ) predominantly dark brown.

Terminalia (n = 1) ( Figs.29–31 ). Epandrium uniformly microtrichose, longer than the hypandrium, with 5 (left) or 8 (right) upper and 6 (left) or 5 (right) lower setae;upper setae in two parallel curved rows adjacent to the posterior margin, setae of the posterior row longer, lower setae scattered over the ventral region that is neither in a ventral lobe form nor covering the surstylus. Cercus ( Fig. 29 ) reduced to a narrow vertical stripe, setose (setae mostly waved and remarkably long), not microtrichose, without a ventral lobe and anteriorly linked to the epandrium by membranous tissue.Surstylus trapezoid in lateral view ( Fig.29b ), double-walled, outer wall covered with tiny wart-shaped scales (seen in the left surstyli of Fig.29a,b ), bearing a row of setae adjacent to the inner margin;inner wall like a brush, densely covered in the anteromedial area with ca. 40 strong, curved, sharply-tipped setae (seen in the right surstyli of Fig. 29a,b ), and only two blunt prensisetae (one dorsal and one ventral, Fig. 29a,b ); base of surstylus weakly linked to the epandrium by membranous tissue. Decasternum as in Fig. 29a,b . Hypandrium sinuate in the lateral view, triangular in the anterior and posterior views, slightly longer than wide, shorter than the epandrium, anterior margin convex, posterior margin concave; posterior hypandrial process absent; dorsal arch sclerotized, distally sinuate in the anterior and posterior views, laterally perpendicular and widely fused to the posterior hypandrium arms and slightly concave, dorsodistally strongly projected forwards as a half pear-shaped tube (lateral view) dorsally sheltering the aedeagus; gonopods proximally fused to each other, anterolaterally linked to the outer paraphysis by membranous tissue, perpendicular to and membranously linked to the medioposterior margin of the hypandrium, each gonopod bearing one tiny setula on a conspicuous conical-shaped tip. Aedeagus ( Figs. 30a–d , 31 ) relatively small (ca. 1/2 length of the aedeagal apodeme), triangular in the lateral view, elliptical in the dorsal and ventral views, distally covered with seta-like scales, anterior ones short and posteromarginal ones conspicuously long, sharply pointed, distally 3- or 4-branched (longest ones), and fringe-shaped; linked to the aedeagal apodeme by membranous tissue.Aedeagal apodeme curved, rod-shaped, distally expanded laterally. Ventral rod sclerotized,anteroposteriorly flattened, bowl-shaped, laterally flanked by the outer paraphyses, linked to the sclerite composed of fused gonopods by membranous tissue. Outer paraphyses proximally membranous, slightly sclerotized distally, devoid of setae, and linked to the ventral rod by membranous tissue; inner paraphyses not recognizable (probably absent or fused to each other as a shelter, dorsally embracing the aedeagus). Ejaculatory apodeme ( Fig. 30e,f ) strongly sclerotized, somewhat similar in profile to the generalized tripunctata type of genus Drosophila of Throckmorton (1962: 242, fig. 19.34); in the lateral view ( Fig. 30e ), plate 54% of the handle length, and the handle 74% of the aedeagal apodeme length ( Fig. 30b ), inner angle ( Fig. 30e ) between the handle and plate ca. 90°; plate spatulate, as long as wide, in the posterior view ( Fig. 30f ).

♀. (n = 3). Differences compared to males:No obvious differences in external morphology. Measurements: Frontal length about 0.44 (0.40– 0.46) mm, frontal index about 1.45 (1.42–1.50), top to bottom width ratio about 1.36 (1.32–1.44), or1 / or3 ratio about 1.30 (1.06–1.50), or2 / or1 ratio about 0.59 (0.50–0.65), postocellar setae about 38 (35–42) % of the frontal length, ocellar setae about 65 (59–69) % of the frontal length; vt index about 0.83 (0.78–0.88); vibrissal index about 0.34 (0.27–0.42). Cheek index about 10 (9–11). Eye index about 1.07 (1.06–1.09).

Thorax length about1.43 (1.36–1.48) mm,dc index about 0.44 (0.42–0.46), scut index about 1.40 (1.38–1.42), sterno index about 0.89 (0.77–1.00).

Wing length 2.30 (2.24–2.41) mm, length to width ratio about 1.90 (1.83–2.00). Indices: C = 1.81 (1.76–1.85), hb = 0.76 (0.71–0.81), 4C = 1.32 (1.24–1.40), 4v = 1.84 (1.65–2.00) 5x = 1.14 (1.00–1.29), M = 0.58 (0.53–0.60), prox. X = 0.90 (0.82–0.93).

Terminalia. Not analyzed.

Distribution. Costa Rica (Province of Cartago).

Biology. Unknown.

Comments. All specimens are partially covered with mold, and many setae are missing or broken. It seems that the epithet tempifera stands for the large hourglass-shaped dark spot of the frons. According to Malloch (1924b), this character also occurs in Stegana interrupta Malloch 1924a collected from the same locality and in Stegana horae Williston, 1896 , from Saint Vincent Island (Caribbean Sea).

Figures

Figure 26 Stegana tempifera Malloch, 1924, labels of male holotype #23.

Figure 27 Stegana tempifera Malloch, 1924, male holotype #23, Higuito, San Mateo, Alajuela, Costa Rica [Type Number 26680, USNM], habitus, two views: a, oblique dorsal, b, left lateral, c, thorax and wings dorsal, d, abdomen dorsal. Scale bar = 1 mm.

Figure 28 Stegana tempifera Malloch, 1924, male holotype #23, Higuito, San Mateo, Alajuela, Costa Rica [Type Number 26680, USNM], habitus, three close-up views: a, head dorsal, b, terminalia posterior, c, right wing dorsal. Scale bars = 1 mm.

Figure 29 Stegana tempifera Malloch,1924,male holotype #23, Higuito,San Mateo,Alajuela,Costa Rica [Type Number 26680,USNM],external terminalia,two views:a,epandrium [accidentally broken during dissection], surstyli, and cerci, posterior, b, idem, oblique posterior. Scale bar = 0.1 mm.

Figure 30 Stegana tempifera Malloch, 1924, male holotype #23, Higuito, San Mateo, Alajuela, Costa Rica [Type Number 26680, USNM], inner terminalia, several views:a, hypandrium+gonopod, aedeagus, aedeagal apodeme, ventral rod, and outer paraphyses, anterior (dorsal), b, idem, left lateral, c, idem, oblique posterior, d, idem, posterior (ventral), e, ejaculatory apodeme left lateral, f, idem, posterior. Scale bar = 0.1 mm.

Figure 31 Stegana tempifera Malloch, 1924, male holotype #23, Higuito, San Mateo, Alajuela, Costa Rica [Type Number 26680, USNM], five views of the aedeagus, aedeagal apodeme, ventral rod, and outer paraphyses, from dorsal through ventral. Scale bar = 0.1 mm.