Rhophitulus xenopalpus new species

(Figures 19–39)

Diagnosis. Rhophitulus xenopalpus n. sp. can be easily recognized by the enlarged and flattened labial palpi (Fig. 25), which are also present in R. labiosus n. sp. (Fig. 3). Additional diagnostic features of Rhophitulus xenopalpus n. sp. are: pale yellow mandibles, clypeus, lower paraocular area, pronotal lobe, and almost all of the legs on males; labral plate as wide as long, with distal margin rounded (Fig. 26); ventral margin of midfemur of females with acute expansion; mesepisternum of females with strongly curved hairs on ventral portion; T1–T2 of females light brown (Fig. 20).

Description. Holotype female. Approximate body length: 4.1 mm; maximum head width: 1.3 mm; maximum mesoscutum width: 1.0 mm; forewing length: 2.8 mm; maximum width of T2: 1.2 mm. Coloration. Integument mostly black. Pronotal lobe (Fig. 20), basal half of anterior surface of foretibia and basal portion of midtibia pale yellow; tegula translucent with small yellow spot. Mandible, underside of antennal fagellum, proboscis (Fig. 25), labral plate (Fig. 26), tibial spurs, wing veins, pterostigma, legs, and T1–T2 light brown (Fig. 20); marginal zone of metasomal terga translucent light brown. Pubescence. Predominantly white and finely branched. on vertex, gena, mesoscutum, scutellum, apex of hind femur, prepygidial and pygidial fimbria with yellowish brown hairs. Head with decumbent branched hairs, densely pilose on upper half (mainly around the antennal sockets), gradually sparser towards clypeus (Fig. 19); labrum with dense and simple hairs (labral plate excluded) (Fig. 26); scape with decumbent and minute hairs; compound eyes glabrous; vertex, mesoscutum, and scutellum with short hairs, 3x longer than the diameter of punctures. Pronotal collar, edge of pronotal lobe, metanotum, and metapostnotum with dense, erect, plumose pilosity, 0.5x as long as ocellar diameter (Figs. 20–21); upper half of lateral mesepisternum with short, semidecumbent, branched hairs; ventral portion of mesepisternum with strongly curved hairs apically; lower half of lateral mesepisternum with erect and sparse pubescence, gradually increasing in length towards ventral portion; metepisternum and propodeum with sparse and minute hairs; lateral corners of propodeum with long plumose hairs; tibial scopae with long, simple, sparse hairs (those on anterior surface 1.2x as long as the maximum width of tibia) (Fig. 20); hind basitarsus with sparse and short hairs. Metasomal terga with tiny and short hairs on T1–T2 (hairs 2.x as long as puncture diameter), becoming denser towards the apex of metasoma; premarginal line of T1–T3 with sparse and simple hairs; premarginal line of T4 densely pilose, hairs 0.7x as long as the length of marginal zone; disc of S1–S4 with sparse erect plumose hairs; distal half of S5 with dense, semidecumbent, plumose hairs. Integumental surface. Densely punctate, integument between punctures smooth and shiny; pronotum, metepisternum, propodeum, and outer surface of hind basitarsus strongly reticulate between punctures. Upper half of head with dense and deep punctures (≤0.5 pd), becoming gradually sparser and shallow towards clypeus (>4 pd on clypeus) (Fig. 19); labral plate and facial fovea smooth; vertex, mesoscutum, scutellum, and metanotum densely punctate (≤0.5 pd), punctures on metanotum shallower in comparison to mesoscutum (Fig. 21); metapostnotum slightly depressed, with irregular striations (Fig. 21). Metasomal terga densely punctate (≤1 pd), premarginal area smooth; marginal zone of T1–T3 punctate; marginal zone of T4 weakly punctate; metasomal sterna slightly reticulate between punctures; pygidial plate with evident transverse microsculpture. Structure (measurements in mm). Head 1.1x wider than long (1.3:1.17); first labial palpus slightly enlarged and longer than subsequent palpi (Fig. 25); labral plate as wide as long (0.28:0.22), distal margin rounded (Fig. 26), and basal portion with two slightly inflated areas; tentorial pit at intersection of outer subantennal and epistomal sutures; compound eyes 1.8x longer than wide (0.82:0.46), inner orbits slightly convergent below (upper: 0.85; lower: 0.77); clypeus 2.1x wider than long (0.77:0.37); frontal line shallow; upper paraocular area flat, not inflated; facial fovea 3.1x as long as wide (0.22:0.07); gena narrow in lateral view, 0.5x as wide as compound eyes. Forewing with two submarginal cells, posterior margin of first submarginal cell longer than the second; 1m-cu reaching second submarginal cell at the basal half; mid and hind tibial spurs finely serrate; mid tibial spur 0.8x as long as basitarsus (0.26:0.31); hind tibial spurs with similar length; tergal marginal zone depressed in comparison to disc; tergal disc flat adjacent to pregradular area (Fig. 20); T1 with lateral line; lateral fovea of T2 large and slightly depressed; pygidial plate V-shaped and flat.

Paratype male (from Tucumán, Argentina). Approximate body length: 3.8 mm; maximum head width: 1.1 mm; maximum mesoscutum width: 0.9 mm; forewing length: 2.7 mm; maximum width of T2: 0.9 mm. Similar to female, except for the following pale yellow parts: mandible, clypeus, lower paraocular area, apex of femur, anterior surface of foretibia, basal half of mid and hind tibia, and tarsus. Apex of metasoma light brown; metasomal sterna with dense, short, plumose hairs. Structure (measurements in mm). Head 1.1x wider than long (1.5:1.3); labral plate 2x wider than long (0.28:0.14); compound eyes 1.8x longer than wide (0.88:0.48), inner orbits convergent below (upper: 1.0; lower: 0.91); clypeus 1.4x wider than long (0.65:0.45); antennal flagellum longer than maximum head width; facial fovea 2.8x longer than wide (0.14:0.05); gena narrow in lateral view (as in the female); mid tibial spur 0.8x as long as basitarsus (0.27:0.4); hind tibial spurs with similar length; outer margin of hind tibia toothed; tergal marginal zone slightly depressed in comparison to disc; metasomal terga with postgradular area depressed in comparison to disc; T1 with lateral line; lateral fovea of T2 slightly depressed; pygidial plate absent; distal margin of T7 slightly emarginated (Fig. 28); S6 with U-shaped emargination distally (Fig. 29); apical lobes of S7 constricted basally and with few coarse hairs (Figs. 30–31); base of genital capsule with small dorsal sclerite; gonocoxite with oblique lateral impression (Figs. 35–35); cuspis of volsella elongate (Fig. 34); gonostylus densely pilose apically (Figs. 34–36).

Variation. Females normally have lighter colored T1–T2 (in some cases also T3) compared to apical brown metasomal terga (Figs. 20, 27).

Stylopized specimen. One female parasitized by Strepsiptera is recorded from Cadillal (Catamarca, Argentina). Differently from the normal females, this stylopized female has a yellow spot on the central portion of the clypeus and lacks curved hairs on ventral portion of the mesepisternum. It shows a larger yellow area on the basal portion of all tibiae, and T1–T2 are brown like the remaining apical terga (Figs. 37–39). In andrenine bees the female parasitized by Strepsiptera often have altered expression of secondary sexual characters, i.e., they demonstrate masculinized traits, such as conspicuously reduced hairs on hind legs, altered morphology of pygidium, and the presence of yellow or white facial maculation otherwise typical of the males (Pérez 1886; Salt 1927; Straka et al. 2011). This is the first record of a stylopized specimen of Rhophitulus .

Distribution. ARGENTINA: Catamarca and Tucumán. The species is found in open vegetation in the Chacoan subregion of the Neotropics, close to the Andean cordilhera.

Type material. Holotype female (AMNH), " Argentina \ Tucumán: 6km SW Tapia\ XI-20-1993 J.G. Rozen". Paratypes, Argentina, Catamarca: 1 female (MZSP), " Argentina: Catamarca\ Prov., Copacabana\ 14 November 1998 \ A. Ugarte Peña"; 1 female (AMNH), " Argentina: Catamarca\ Prov., Copacabana, 16 km \ SE Tinogasta XI.15.98\ Rozen, Ugarte, Navarrete". Tucumán: 2 females and 1 male (AMNH), same collection data as the holotype; 2 males (MZSP) (one with terminalia dissected), " Argentina \ Tucumán: 6km SW Tapia\ XII-2-1993 J.G. Rozen"; 1 female (parasitized by Strepsiptera) and 1 male (AMNH), " Argentina: Tucaman Prov.\ 11 km N Cadillal XI.17.98\ Rozen, Ugarte, Navarrete"; 2 female (MZSP), " Argentina, Tucuman:\ 11km NW El Cadillal\ Nov.7,1991\ J.G. Rozen, L. Pena\ & A. Ugarte"; 1 male (AMNH), " Argentina \ Tucumán: 11km NW\ Cadillal XII- 4-1993 \ J.G. Rozen"; 1 male (MZSP), " Argentina, Tucumán:\ El Cadillal to 12 km N\ October 30, 1989 \ J.G. Rozen & A. Roig".

Etymology. The epithet refers to the peculiar morphology of the labial palpi, from the Latin xenos, meaning strange.