Scaptomyza (Mesoscaptomyza) pipinna, Goñi & Vilela, 2016

Goñi, Beatriz & Vilela, Carlos R., 2016, Two new Neotropical species of Drosophilinae (Diptera: Drosophilidae) from Uruguay, Zoologia (e 20160142) 33 (6), pp. 1-13 : 9-10

Scaptomyza (Mesoscaptomyza) pipinna sp. nov.

Figs. 64- 78

urn:lsid:zoobank.org:act:0BCA88CF-93ED-4A78-85A6-89D36ED04183

Types. Holotype male (dissected), labelled: Uruguay – Departament of Rocha, Sarandí del Consejo [creek, near north shore of Laguna (lagoon) de Castillos ], 34°16’86”S, 53°59’08”W, M.E. Martinez coll. /segada [net swept over grass], 15.X.1994 / pradera [prairie]/ Scaptomyza pipinna ♂ Goñi & Vilela /HOLOTIPO [red label]” ( MZSP) .

Diagnosis. Frons yellowish-brown, dull, lacking defined stripe (present in Scaptomyza striaticeps ), orbits and anterior region lighter, ocellar triangle dark brown, antennae brown, medial vertical convergent and conspicuously long (longer than frontal length), vt index 1.63; scutum light brown, with three prominent brown longitudinal stripes, the central one extending to the end of scutellum; one pair of small presutural dorsocentrals; a single dorsal pleural stripe extending to postscutellum; wing clear; epandrium devoid of upper and lower setae (lower setae present in S. striaticeps ), cercus slightly fused to epandrium on anteroventral corner (not fused in S. striaticeps ), aedeagus straight (bent upwards in S. striaticeps ) in lateral view.

Description. Male (n = 1). Head. Frons mostly yellowish brown, dull, anterior 1/3 light yellow and medially brownish, devoid of a broad blackish stripe from ocelli to anterior margin; frontal length 0.24 mm, frontal index = 0.83, top to bottom width ratio = 1.42. Frontal triangle indistinct; ocellar triangle prominent dark brown, about 40% of frontal length. Orbital plates light brown, subshining, apically divergent from eye margin, about 80% of frontal length. Orbital setae black, or2 just outside of or1, shorter and about one-half diameter of proclinate setae of pedicel, distance of or3 to or1 = 40% of or3 to vtm, or1/or3 ratio = 0.86, or2/or1 ratio = 0.50, postocellar setae 80%, ocellar setae 80% of frontal length. Medial vertical convergent and remarkably long (longer than frontal length) ( Fig. 64), vt index 1.62. Postocellar setae cruciate at tip. Face yellowish, dull; facial carina rudimentary, not sulcate; vibrissal index = 0.57. Cheek index = 7.50. Eye index = 1.25. Antenna brown, globose, pedicel with two larger setae, anterior ones proclinate and larger, reaching tip of flagellomere I, posterior ones directed outwards. First flagellomere with median-sized hairs; length to width ratio = 1.00. Arista with 3 upper and 2 lower branches, plus one long terminal fork; 6 inner branches. Proboscis light brown, elongated, palpus dark brown with 1 terminal seta as long as vibrissa, but thinner, 1 smaller subterminal seta half the length of terminal, plus several fine setulae.

Thorax. Length = 0.78 mm. Scutum light brown, subshining, bearing three conspicuous, brown, longitudinal stripes, the central one extending to the tip of scutellum, the two lateral ones lying outside the dorsocentrals, extending onto the sides of scutellum ( Fig. 66); one dorsal, brown, conspicuous, pleural stripe, narrow at proepisternum, widening at katepisternum, extending to postscutellum and including meso and metathoracic spiracles. Apparently 2 irregular rows of acrostichals (most of them are broken off) at presutural area. Apparently only one postpronotal. Transverse distance of dorsocentral setae 143% of longitudinal distance; dc index undetermined. A pair of additional small dorsocentrals, twice as long as adjacent acrostichal setulae, just anterior to transverse suture. Prescutellar setae absent. Scutellum with a large, diffuse, brown stripe at center, light brown laterally, subshining; distance between apical scutellar setae about 67% of that between apical and basal one, basal setae parallel, apical setae cruciate at median region; scut index undetermined. Pleura yellow at lower half, with a brownish stripe at upper half, subshining, sterno index undetermined; median katepisternal seta 50% of anterior one and noticeably thinner. Proepisternal seta absent. Halter long, pale yellow, contrasting with brownish background of pleural longitudinal stripe. Legs uniformly yellow, except metatarsomere V, brownish. One black seta at base of inner surface of mesotarsomere I, apical setae on protibia and mesotibia, the latter spur-shaped; preapicals on all three.

Wing. Hyaline, length 2.00 mm, length to width ratio = 2.42. Indices: C = 3.31, ac = 2.00, hb = 0.35, 4C = 0.67, 4v = 1.46, 5x = 1.57, M = 0.46, prox. x = 0.42.

Abdomen shining dark brown with a dorsal pattern of pale yellow areas except on the last tergite.

Terminalia ( Figs. 67-78). Epandrium microtrichose on posterior area; upper and lower setae absent; ventral lobe pointed at tip, bearing 1 robust terminal seta and 2 thin, subterminal setae ( Fig. 67) arranged in tandem, not covering surstylus. Cercus mostly microtrichose on anterior area, slightly fused to epandrium on anteroventral corner; ventral surface without any sclerotized spine, but medially bearing four setae emerging from an irregular, sclerotized spot, preceded by a membranous, turned frontwards, rectangular area; ventral cercal lobe absent. Surstylus not microtrichose extensively fused to epandrium, with about 4 long, marginal setae, and three smaller, thinner setae on outer surface ( Fig. 68). Decasternum with straight anterior and posterior margins, the former slightly incised at middle (not shown in Fig. 67 because anterior margin is curved frontwards), the latter medially protruding sharply backwards, as in Fig. 67. Hypandrium short, about half the length of epandrium, anteriorly narrow, anterior margin convex; posterior hypandrial process and dorsal arch absent ( Fig. 69); gonopod posteriorly more sclerotized, laterally double-walled, linked to paraphysis by membranous tissue, bearing one tiny setula on middle inner margin ( Figs. 70, 71). Aedeagus tiny, straight in lateral view, tube-shaped; distal tip membranous ( Figs. 70-76). Paraphysis triangle-shaped ( Fig. 74), ca. 2/3 aedeagus length, double-walled ( Fig. 76), blunt at tip, bearing two tiny terminal setulae ( Figs. 73, 74). Aedeagal apodeme rod-shaped, longer than aedeagus, posteriorly fused to it ( Figs. 75, 76). Ventral rod absent.

Female. Unknown.

Distribution. So far only known from its type locality.

Remarks. Scaptomyza pipinna sp. nov. belongs to the subgenus Mesoscaptomyza. The male terminalia shows similarities with those of two species depicted by HACKMAN (1959) and WHEELER & TAKADA (1966: figs. 15.10 and 18.10).The straight aedeagus, although cylinder-shaped, reminds to those of S. paravittata Wheeler, 1952, from California, and S. setosa Wheeler & Takada, 1966 , from Ecuador, which are somewhat cone-shaped; its decasternum and epandrium are similar to those of the Colombian S. striaticeps , from which it differs mainly by the absence of the paralobe sensu HACKMAN (1959).

Etymology. The specific name pipinna is a noun in apposition, in allusion to the tiny size (~ 81 µm long) of the aedeagus.

Note. While transferring the terminalia sclerites from the microscope slides to the glass microvial, the epandrium and hypandrium have been accidentally lost and only the aedeagus+aedeagal apodeme and paraphyses, together with the remains of abdominal tergites and sternites, are preserved in the microvial attached to the double-mounted holotype.