Drosophila lecythus sp. nov.

urn:lsid:zoobank.org:act: 7A9CBBE4-FD74-4DE7-832D-AE4407E77CA4

Figs. 3–5, 6a, 7a

Diagnosis

Yellowish brown body colour. Arista with five dorsal, two ventral branches, plus a terminal fork. Two prominent oral bristles. Yellowish brown thorax. Transparent wings, slightly yellowish. One row of cuneiform bristles (Fig. 3F) on the anteroventral region of the fore femur. Yellow abdomen with the 1st and 5th tergites devoid of dark distal band, 2nd to 4th tergite with dark distal bands, and 6th with the presence of a dark spot in the median region, may also show variations in the dot pattern, having the 5th with a small dot with no definite shape or with the distal bands of the tergite lightly painted and a tiny spot on the 6th tergite. Siege not fused to the epandrium. Hypandrium shield-shaped. Gonopodium with a large bristle. Paraphysis fused to the gonopodium and with a medium bristle compared to that found on the gonopodium. Tubular aedeagus, both apical surfaces dorsally and subapical ventrally membranous; subapical part laterally with a pair of serrated processes. Spermathecal inner capsule spherical in shape and with slight wrinkling on the surface.

Etymology

The epithet lecythus refers to the shape of the fruit (Latin lecўthus) that gives name to the tree family Lecythidaceae Poit, whose flowers are used as adult feeding and larval breeding sites.

Material Examined

Holotype (Figs. 3a–c, f, 5a–e)

Caxiuanã, Brazil — ♂ (dissected, terminalia in microtube, dry mounted). Captured in nature with an entomological net over the fallen flowers of the Bertholletia excelsa. Location north 01º37’S / 51º19’W and 01º54’S/ 51º58’W and south 02º15’S/ 51º15’W and 02º15’S/51º56’W. 30 Jan. 2020. V. Queiroz-Maciel col. MPEG 02033853.

Allotype (Figs. 3d, e, g, 6a, 7a)

Caxiuanã, Brazil — ♀ (dissected, terminalia in microtube, dry mounted). Captured in nature with an entomological net over fallen flowers of the Bertholletia excelsa. Same data as for holotype. MPEG 02033854.

Paratypes (Figs. 4a–d)

Caxiuanã, Brazil —9 ♂♂ (2 dissected, terminalia in microtubes, dry mounted, and 7 not dissected in ethanol). Captured in nature with an entomological net over the fallen flowers of the Bertholletia excelsa. Same data as holotype; MPEG 02033855 to MPEG 02033863— 6 ♀♀ (2 dissected, terminalia in microtubes, dry mounted and 4 not dissected in ethanol). Captured in nature with an entomological net over the vfallen flowers of the Bertholletia excelsa. Same data as for holotype; MPEG 02033864 to MPEG 02033869.

Description

Males of the species

External morphology of holotype: total length (body including wings) 2.45 mm, body length without wings 1.8 mm. Yellowish brown body.

HEAD. Arista with five dorsal and three ventral branches, plus terminal bifurcation and thin inner branches. Yellow Orbital plate, frontal length = 0.24 mm, frontal index = 0.75, the upper to lower width ratio = 0.17. Medial vertical bristle close to lateral vertical bristle with direction opposite to orbital plate, index vt = 0.22, index or1- or3 = 0.11, index or 2- or 1 = 0.02. Yellowish brown ocellar triangle, yellow ocelli with partially darkened outline; yellowish brown frontal triangle, yellowish edge, yelloww Gena and postgena, cheek index = 7.7. Two prominent oral bristles, vibrissa index = 0.6. Prominent Carina and not grooved, yellow proboscis, scarlet eyes, eye index = 1.48.

THORAX.Yellowish brown, thorax length 0.73 mm, six rows of acrostichal bristles between the two dorsocentral bristles. Index h = 0.96, index dc = 0.61. Yellowish Scutellum; basal scutellar bristles convergent, index scut = 1.08. Median katepisternal bristle smaller than anterior, sterno index = 0.52. Yellow legs.

WINGS. Slightly yellowish transparent, bM-Cu hyaline, wing length 1.86 mm, wing width 0.81 mm, length to width ratio = 2.3 mm. Indices: C = 3.82; ac = 1.85; hb = 0.59; 4e 4C = 0.67; 4v = 1.74; 5x = 1.45; M = 0.45 and prox. x = 0.55.

ABDOMEN. Yellow with distal bands, 1st tergite without distal dark bands, 2nd to 4th tergite with dark distal bands interrupted in the median region, 5th without lateral dark band and 6th with the presence of a black spot, which may be vestigial and almost imperceptible, a rectangular shape in the median region and which does not reach the distal margin of tergite.

TERMINALIA ♂ (Fig. 5a–e). Epandrium microtrichose, two bristles on the dorsal part, ventral lobe with four bristles, two pairs of lower and one inner bristle, bristle on the epandrium, bristles on the dorsal region of the epandrium distant from each other. Surstylus with 9–10 primary teeth arranged in an L-shaped row and 5–6 marginal secondary teeth, and its underside with bristles evident and aligned. Hypandrium with an oval shape and shorter than the epandrium. Decasternum with a hardened membrane. Gonopod with a well-developed bristle fused to the paraphysis. Paraphysis with bristles median relative to the bristle of the gonopod.

AEDEAGUS (Fig. 5a–c). Aedeagus tubular; ventral median region membranous and conspicuously expanded into a triangular shape in lateral view (Fig. 5b); subapical part laterally with a pair of serrated processes. Aedeagal apodeme shorter than edeagus, flattened laterally.

Females of the species

External morphology: total size (body including wings) 2.98 mm, body length without wings 2.56 mm. Body yellowish brown.

THORAX. Yellowish brown, thorax length = 1.25 mm, six rows of acrostichal bristles between the two anterior dorsocentral bristles. h index = 1.02, dc index = 0.69. Scutellum yellow; basal scutellar bristles convergent, scut index = 1.08. Median katepisternal bristle smaller than above, sterno index = 0.74. Yellow legs.

WINGS (Fig. 3g). Transparent yellow, bM-Cu hyaline, wing length 2.25 mm, wing width 0.97 mm, length to width ratio = 2.32. Indices: C = 4.13; ac = 2.49; hb = 0.87; 4e 4C = 0.45; 4v = 2.42; 5x = 1.30; M = 0.63 and prox. x = 0.72.

ABDOMEN. Yellow with distal bands, 1st tergite without pigmentation, 2nd to 4th tergite with pigmented and median interrupted distal bands, 5th without pigmentation and 6th with the presence of a dot in the median region.

TERMINALIA (Figs. 6a, 7a). Oviscapt valve pointed apically and sclerotinized, with 6–7 marginal and 4–5 discal teeth. The inner capsule of spermatheca is spherical in shape and with basal wrinkles. Spermathecal duct slightly invaginated and with microvillous edges.

Variation in paratypes

Abdomen: Distal band of the 1st tergite without pigmentation, 2nd to 4th tergite with horizontally pigmented distal bands. 5th tergite without pigmentation or with a rounded spot in the median region of the tergite, and the 6th tergite with the presence of a larger spot than that of the 5th tergite (Fig. 4). Females with the number of aristal branches ranging from 8 to 10, not including the terminal bifurcation.

Distribution

Known for the Caxiuan„ National Forest, Melgaço and Portel (PA) and Mocambo Reserve, Belém (PA), where two males (MPEG-DIP 12031918 and MPEG-DIP 12031919) emerged from Eschweilera spp. flowers in 1988, and one male (MPEG-DIP 12032089) emerged from Clusia grandiflora in 1987, all identified and labelled, initially as Drosophila mediosignata like (Dobzhansky & Pavan 1943) and later as Drosophila mesostigma like (Frota-Pessoa 1954). The specimens have been reviewed and deposited in the entomological collection of the Museu Paraense Emilio Goeldi, Brazil.

Relationship to other species

Although the phylogeny alone could not assert the placement of this species among the four subgroups of tripunctata, we suspect, from the morphology, that the new species is closely related to the other five species with cuneiforms bristles on the fore femur present in the subgroup III: Drosophila mediostriata, Drosophila mesostigma Frota-Pessoa, Drosophila frotapessoai Vilela and Bächli, Drosophila paramediostriata Townsend and Wheeler and Drosophila converga Heed and Wheeler.

Biology of the species

We collected 2,052 individuals of the new species flying over fallen flowers of six species of Lecythidaceae (Couratari multiflora, Bertholletia excelsa, Eschweilera grandiflora, Eschweilera coriacea, Eschweilera ovata and Lecythis idatimon), in addition to 353 individuals that emerged from fallen flowers of the Bertholletia excelsa (n = 44) and of the Eschweilera grandiflora (n = 309).