Mydrosoma sabarensis, Silveira, Fernando A. & Martines, Roderic B., 2009

Silveira, Fernando A. & Martines, Roderic B., 2009, A new species of Mydrosoma Smith with a key to Brazilian species of the genus and a discussion on the classification of the Dissoglottini (Hymenoptera: Colletidae), Zootaxa 2105, pp. 32-42 : 33-38

Mydrosoma sabarensis sp. nov.

( Figs. 1–8 , 9 e)

Diagnosis. Mydrosoma sabarensis sp. n. has some of the major diagnostic features of diphaglossine bees, such as a reduced pterostigma, which is much shorter than the prestigma. In the female, F1 is longer than F2 but, as normal in Dissoglotini, not petiolate and less than twice as long as the other flagellomeres. In both sexes, the glossa is only moderately bifid, resembling the bilobed condition of other colletid (and other Dissoglottini ) bees. The size and general pilosity pattern of this new species ( Figs. 2–3 ; 6–7) and some details, such as presence of the stipital brushes ( Fig. 4 , see below), 2nd submarginal cell smaller than 3rd, long tarsal claws and patch of plumose hairs on latero-ventral surface of T1, resemble M. fallax ( Moure, 1953) . This species was previously considered to belong to Ptiloglossidia and is known only from the Argentinean province of Salta. It can be distinguished from this species, however, by the following characters. In both sexes: preoccipital ridge present (more strongly developed in males) (absent in M. fallax ); metapostnotum dull microreticulate, striate basally (in female, only laterally) (shiny microreticulate, not striate in M. fallax ); arolia present (absent in M. fallax ). In female: longitudinal midline of clypeus punctate throughout (smooth and shiny almost to the apical margin in M. fallax ); mesosoma with white, transverse, hair band anteriorly, fuscous elsewhere (completely fuscous dorsally, white on ventro-lateral portion of mesepisternum in M. fallax ); basitibial plate not delimited by carinae, its surface completely hidden by flat apressed hairs (in M. fallax , delimited posteriorly by carina, only partially hidden by thin, semi-erect hairs for most of surface); pilosity on front margin of hind tibia fuscous, composed of relatively long, densely plumose hairs (white, composed of long hairs, with short branches restricted to their apical half in M. fallax ). In male: frons, vertex and most of gena blackish brown (head entirely ferruginous in M. fallax ); pilosity on disc of terga blackish (entirely yellowish in M. fallax ); hind tibia expanded distad, three times as wide distally as hind basitarsus (normal, twice as wide as hind basitarsus in M. fallax ); hind tibial spurs relatively short, outer spur half as long as inner one (long and more equal in size in M. fallax ); ventral surface of hind femur flattened, with row of spine-like bristles on posterior margin (ventral surface of hind femur convex, without such bristles in M. fallax ); S6 with specialized patches of plumose hairs laterally and a triangular sulcus basally (S6 with no such patches and with a long, relatively wide, longitudinal sulcus from the base almost to the apex of the sternum). Distinctions between M. sabarensis and the other species of Mydrosoma known to occur in Brazil are given in the key below.

Description. Female (Holotype):

Measurements (mm): Approximate body length: 12.2; maximum head width: 3.5; fore-wing length: 7.5; length of 2nd and 3rd submarginal cells, on their posterior margins: 0.6 and 0.7; length and width of labrum: 0.4 × 0.9; length and width of malar area: 0.3 × 0.6; clypeocellar distance: 2.7; ocellocular distance: 0.4; ocellar diameter: 0.2; interantennal distance: 0.6; ocelloccipital distance: 0.3; antennocular distance: 0.4; length of F1 and F2: 0.3 and 0.2.

Structure: Glossa bilobed ( Fig. 4 ); clypeus convex, emarginate apically; supraclypeal area convex; malar area distinct, about half as long as basal width of mandible and about as long as flagellar diameter; frontal line weakly carinate, reaching mid ocellus; paraocular carina evident above level of antennal socket, extending up to ocellus level; vertex with well defined preoccipital ridge; F1 one third as long as scape, conical; inner orbits of eyes parallel, except convergent above; scutoscutellar suture relatively wide and deep between the axillar sutures, partially hidden by pilosity; scutellum convex, with medial, weak but well defined longitudinal depression; second submarginal cell smaller than third; vein 1st m-cu reaching second submarginal cell in its basal fourth; 2nd m-cu reaching third submarginal cell at its apical sixth; basitibial plate only indicated by dense, triangular patch of short, flat appressed hairs, not delimited by marginal carinae; external surface of hind basitarsus flat; mid and hind tibial spurs serrate; apical zone of T1–T4 not depressed, except laterally on T2–T4; pygidial plate wide, its apical margin broadly rounded, lateral margins folded upward basad, forming a low marginal lamella.

Color: Body black, except: dark ferruginous as follows: mandible (apex blackish); apical two thirds of labrum; malar area; inner surfaces of front and mid legs and basitarsi and distitarsi of all legs; ferruginous ventrally on F3–F9 and whole of F10; brown on marginal zones of T1–T4 and S1–S4, apical margins of T1–T4 brown with light blue-violaceous reflections. Wing membranes and veins ferruginous, except C and Sc+R and tegula, which are blackish-ferruginous.

Pubescence: On basal two-thirds of stipes yellow, forming dense brush ( Fig. 5 ), the hairs relatively long and thick with fine apexes curved posteriorly; on apex of labrum, golden, on compound eyes, very short and sparse; on gena light yellow; on scape minute and black on anterior surface, with patches of moderately long, simple, erect hairs on each side, black on outer and yellow on inner side; on mesosoma, fuscous, except for a wide transverse stripe of white hairs anteriorly and for a narrow whitish band of densely plumose, short hairs partially hidden under the longer fuscous pilosity on the anterior margin of the scutellum; scopa white on trochanter, black on femur, except for a white tuft subapically on anterior surface; on T1–T4, fuscous on disc (except yellowish, laterally on T2–T3), on marginal zones, forming wide bands of simple, long yellow hairs, widely interrupted medially; under these bands, forming a thin apical band of plumose, pale-yellow hairs; on latero-ventral surface of T1 forming a patch of finely plumose hairs, each one fuscous basally, white apically; on T5 black, densely plumose; on S2–S5 forming apical bands of simple yellowish hairs occupying the medial half of the sternal margins, and apico-lateral bands of plumose white hairs.

Sculpture: Clypeus sparsely punctate apically, denser basally, the surface between punctures smooth and shiny; on supraclypeal area punctures dense laterally; on paraocular area dense; near ocelli, fine and very sparse; on mesosoma fine, largely hidden by pubescence, except on metapostnotum which is striate basally (more so laterally) and dull reticulate throughout; on posterior surface of propodeum fine and sparse, the surface shiny reticulate; on metasomal terga, relatively fine and moderately dense basally, sparser distad; on marginal zone of T3–T4, fine and dense under lateral bands, microlineolate and shiny between them; on T5 coarser and uniformly dense; on sterna, fine and dense.

Variation: In the paratypes from Sabará and Domingos Martins, mandible with two subapical teeth, the basalmost smallest; their mandible light ferruginous up to the base of the basalmost tooth, which is blackishferruginous, while the apical tooth is dark ferruginous; labrum brown. In the paratype from Domingos Martins, the patch of plumose hairs on latero-ventral surface of T1 and those on femoral scopa are entirely white. In this paratype, the posterior margin of mesoscutum has a thin whitish band of densely plumose, short hairs partially hidden under the longer fuscous pilosity, but the similar band on the anterior margin of the scutellum of the holotype is absent.

Male

Measurements (mm): Approximate body length: 10.7; maximum head width: 3.0; fore-wing length: 8.7; length of 2nd and 3rd submarginal cells, on their posterior margins: 0.4 and 0.7; length and width of labrum: 0.3 × 0.7; length and width of malar area: 0.3 × 0.5; clypeocellar distance: 2.2; ocellocular distance: 0.3; midocellar diameter: 0.3; ocelloccipital distance: 0.3; interantennal distance: 0.5; antennocular distance: 0.3; interocullar distance: 3.0; length of F1 and F2: 0.3 and 0.4.

Structure: Mandible bidentate, the apical tooth longer than the subapical one; malar area more than half as long as basal width of mandible and longer than flagellar diameter; clypeus convex; disc of supraclypeal area at same level as clypeus; flagellum not serrate; F1 conical; eyes with short and sparse hairs; scutoscutellar suture wide and deep, anterior surface of scutellum almost vertical; second submarginal cell much smaller than third, almost triangular in shape; ventral surface of hind femur concave on its basal third, flat on the distal two-thirds ( Fig. 8 ); mid and hind tibial spurs serrate; hind tibia widened towards its apex, produced into transparent lamella around tibial spur bases anteriorly; hind tibial spurs short, the outer spur half as long as inner one; hind basitarsus very narrow, only slightly wider than second tarsomere, somewhat cylindrical. S6 with deep V-shaped sulcus basally.

Color: Body black, except pale yellow on labrum, basal two-thirds of mandible and paraocular area up to level of antennal socket; pale ferruginous on clypeus, anterior surface of scape and ventral surface of flagellomeres (darker toward apical flagellomeres) blackish-brown on posterior surface of scape and dorsal surface of flagellomeres; light ferruginous on tarsi of all legs; translucent pale yellow on apical margin of T1–T6 (a narrow line on T1, increasingly wide on successive terga to T6) and S1–S5. Wing membranes hyaline with yellow tint; veins ferruginous, except C and Sc+R, and tegula, blackish ferruginous.

Pubescence: Pale fulvous, except: on posterior fringes of all tibiae, blackish brown; posteriorly, on inner margin of hind tibia, forming a band of keirotrichia; on T2–T6 simple, semi-erect and black on disc, with fulvous hairs intermixed on T2; on marginal zones, semi-decumbent, whitish-yellow, forming ill-defined, wide marginal bands; on S6, short and plumose, forming two longitudinal patches on the sides of a mid smooth and shiny area, the patches black on the outer and white on the inner sides. Ventral surface of hind trochanter, near its posterior margin, with two long, ferruginous, spine-like bristles; posterior margin of ventral surface of hind femur with four similar bristles arranged in a row, decreasing in length toward femoral apex ( Fig. 8 );

Sculpture: Labrum impunctate; on clypeus, fine and sparse apically, coarser and denser on base, where surface between punctures is weakly microreticulate; coarse and dense on supraclypeal area, which is coarsely microreticulate between punctures; very fine and sparse, the surface shiny, on upper paraocular area, between eye and lateral ocellus and behind ocelli. On mesosoma fine and dense, except sparser on disc of propodeum, and transversely striate on metapostnotum basally. On metasoma fine and relatively sparse, with smooth marginal zones on terga and sterna; S6 with a wide, smooth and shiny longitudinal area between dense hair patches.

Holotype. Female: “Sabará MG; Brasil 29/04/2001; F. A. Silveira”, “Abelhas da Zona Metalúrgica de Minas Gerais; Ch[ácara]. do Lessa; 7280-21575”, “ Mydrosoma sabarensis Ψ; Silveira & Martines, sp. n.; HOLOTYPUS ”. This specimen was collected at 8:30 a.m. on flowers of a vine of Serjania sp. ( Sapindaceae ) at the border of a forest fragment (deposited at UFMG).

Paratypes. One male and one female collected in the same locality and plant as the holotype and labelled: “Abelhas da Zona Metalúrgica de Minas Gerais; Ch. do Lessa; 8194-24803”, “Sabará MG; Brasil 04/04/2001; R.B. Martines”, “ Mydrosoma sabarensis ɗ; Silveira & Martines sp. n.; PARATYPUS ” and “Sabará MG; Brasil 24/04/2001; R.B. Martines”, “Abelhas da Zona Metalúrgica de Minas Gerais; Ch. do Lessa; 9024- 26946”, “ Mydrosoma sabarensis Ψ; Silveira & Martines sp. n.; PARATYPUS ” (both deposited at UFMG). The male was collected between 9:00 and 10:00 and the female, between 8:00 and 9:00. An additional female labeled: “D[omingos]. Martins; E.S. – Brasil; 18-II-1966; C. Elias”, “ Mydrosoma sabarensis Ψ; Silveira & Martines sp. n.; PARATYPUS ” (deposited at DZUP).

Etymology. The name “ sabarensis ” is a reference to the type locality, the historic town of Sabará.

Comment. The mandibles of the holotype are closed behind the labrum, hiding the teeth. Their apices are apparently worn.

Figures

FIGURE 9. Examples of a possible mimicry complex: a) Melipona quadrifasciata anthidioides Lepeletier, 1836 (Apidae, Apini); b) Gaesischia anthidioides Urban, 1968 (Apidae, Eucerini); c) Exomalopsis aureosericea Friese, 1899 (Apidae, Exomalopsini); d) Monoeca schrottky (Friese, 1902) (Apidae, Tapinotaspidini); e) Mydrosoma sabarensis Silveira & Martines, sp. n. (Colletidae, Dissoglottini); and f) Megachile pseudanthidioides Moure, 1943 (Megachilidae, Megachilini). All female, but Monoeca schrottkyi, which females present similar color pattern. Specimens are approximately in the same scale, except “ d ”, which is about the same size as “ b ”.

FIGURES 1 – 4. Mydrosoma sabarensis sp. n., female holotype: 1) Frontal view of head; 2) dorsal view; 3) lateral view; 4) frontal view of mouthparts (note golden stipital brushes).

FIGURES 5 – 8. Mydrosoma sabarensis sp. n., male paratype: 5) Frontal view of head; 6) dorsal view; 7) lateral view; 8) ventral view of hindfemur (note spine-like bristles along posterior margin).