Lynchiatilla leguera Casal, 1963

Bergamaschi, Antonio C. B., Cambra, Roberto A., Brothers, Denis J. & Melo, Gabriel A. R., 2012, Lynchiatilla Casal, 1963 (Hymenoptera: Mutillidae): a new species from Brazil associated with Paroxystoglossa spiloptera Moure (Hymenoptera: Apidae: Halictinae), and notes on other species, Zootaxa 3548, pp. 55-64 : 59-62

Lynchiatilla leguera Casal, 1963

( Figs 13 , 15–22 )

Lynchiatilla leguera Casal, 1963 . Acta Zool. Lilloana 19: 361. Holotype Ƥ, Argentina, Córdoba, Calera (AMNH).

Description. MALE (hitherto unknown; Figs 13 , 20–22 ). Body length 5.4–8.9 mm (mean 6.25 mm, SD 0.61 mm, n=64). Color: integument of head, mesosoma and legs entirely black, metasoma usually with first few segments orange, becoming ferruginous and then black on apical segments, but sometimes entirely black (see discussion below); palps medium to dark brown; tibial spurs pale white; wings with membrane almost hyaline basally, weakly infuscated apical to cells, veins blackish; body and legs covered with sparse, simple to brachyplumose, white setae, except inner margin of eye with very few long black setae, mesoscutum with decumbent black setae and long white setae intermixed, and T2–T6 with decumbent brownish setae and erect white setae.

Head: transverse in dorsal view, sub-rounded, with dorsal erect brachyplumose pubescence becoming briefly plumose posteroventrally; frons and vertex with medium-sized, very close punctures, gena with finer and denser punctures; eye 0.54–0.60 × as long as medial length of head; ocelli small, distance between eye margin and lateral ocellus 5.54–6.00 × as long as diameter of ocellus; genal carina absent; clypeus convex mesally, its antero-medial margin slightly concave and untoothed; proboscidial fossa large, extending laterally nearly to insertion of mandible; mandible slender, bidentate apically, simple ventrally; scrobal carina reduced to an inconspicuous protuberance between antennal tubercle and eye; antennal tubercle simple, without protuberance or carina; scape with a single longitudinal carina below; first flagellomere as long as second.

Mesosoma: pronotum, mesoscutum and scutellum with medium-sized, very close punctures; tegula convex, without a distinct posterior surface, smooth and shiny but with a few punctures along anterior and lateral margins; scutellum slightly convex; dorsum and posterior face of propodeum broadly reticulate; pronotum with humeral area rounded, anterior and lateral micro-setose tubercles distinct, lateral area with short obliquely vertical carina anteriorly; mesopleuron anterior one-third with small separated punctures and dense micro-punctation, posterior two-thirds with medium-sized, very close punctures, dorsal and ventral areas separated by broad and deep scrobal groove; metapleuron and propodeum laterally mostly smooth and impunctate; forewing with three submarginal and two discal cells, veins 3rs-m and 2m-cu faintly indicated and nebulous.

Metasoma: T1 not constricted posteriorly, sessile and evenly merging with T2, 0.56–0.64 × as long as wide, 0.37–0.40 × length and 0.48–0.61 × width of T2, mostly smooth, with few and small punctures except apically and laterally with small, close punctures; T2 covered with medium-sized, close punctures except base smooth and apex with small, close punctures, with lateral felt line 0.47–0.56 × as long as lateral margin; T3–T6 with small, very close punctures; T7 basal half with medium-sized, very close punctures, apical half with intermixed microgranulate and irregular rugose sculpture; S1 mainly smooth, with strong median longitudinal carina ending anteriorly abruptly near sternal base and forking posteriorly; S2 without felt line; S2 with medium-sized punctures; S3–S6 with small, very close punctures; S7 mainly smooth, with a few small close punctures medially; hypopygium with medium-sized punctures anteriorly and small fine punctures posteriorly, apex with deep, V-shaped, medial emargination; genitalia: paramere with apex simple, basal half not very broad, distal half gradually narrowing toward apex, ventral margin with long setae, except becoming short and sparser on apical one-fourth; volsella with cuspis and digitus short, cuspis with long setae; penis valve with apical tooth and lacking preapical tooth ( Fig. 13 ).

Material examined. Argentina, Jujuy, Huacalera [23°25'46"S 65°21'25"W], 17 km N Tilcara, 2800 m, 6.I.1972, col. D.J. Brothers (2 ♂ 1 Ƥ, AMNH; 62 ♂ 67 Ƥ, DJBC). Uruguay, Rocha, Fortaleza de Santa Teresa [33°59'S 53°32'W], 2.X.1944, col. P.A. Berry, det. Casal 1965 (1 Ƥ, USNM).

Variation. In the sample from Huacalera, there is considerable variation in color and size in both sexes. Males (n=64) have the head, mesosoma and legs always black, but most specimens have the metasoma orange to reddish basally but darkened apically, and a few have it entirely black. The metasomal coloration can be characterized as follows: 3% with at least T2–T4 orange, apical terga becoming darker (e.g. Fig. 21 ); 36% with T2–T3 orange, T4–T7 distinctly darker; 39% with T2 orange, T3–T7 distinctly darker and apically black; 14% with T2 dark ferruginous, T3–T7 black; 6% with entire metasoma, including T2, black (e.g., Fig. 22 ); the metasomal sterna vary in a similar fashion, although their color tends to be slightly paler than the corresponding terga. Two males (8.5 and 8.9 mm long) are considerably larger than the rest (5.4–7.0 mm long, mean 6.17 mm, SD 0.42 mm, n=62); nevertheless, no other morphological differences were found between these two and the others. Such distinct size differences may indicate development on different-sized hosts, as was found for Dasymutilla bioculata ( Cresson, 1865) by Mickel (1924).

Females show color variation across most of the body, the head usually ferruginous and darker than the orange to light ferruginous mesosoma, and the metasoma ferruginous to apically blackish above but light ferruginous laterally and ventrally; the legs are slightly darker than the mesosoma. In 13% of specimens the head is paler, scarcely darker than the mesosoma (e.g. Fig. 15 ), and in 24% it is much darker, almost black (even darker than shown in Fig. 17 ). In 7%, T2 is entirely light ferruginous to orange but appearing darker dorsally because of the dark recumbent pubescence (e.g., Fig. 16 ) and in 9% the entire metasoma (except perhaps for the base of T1) is black (e.g., Fig. 18 ). Although there is a tendency for the whole body to be lighter or darker, the specimen with the darkest head (essentially black) is not that with the darkest metasoma. In addition to these variations in integumental color, there is also some variation in the shape and size of the pubescent spots on T2; they are mostly relatively large, slightly elongate and with the borders somewhat fuzzy (as in Fig. 15 ) but less often (about 8%) round, slightly smaller and better defined (as in Fig. 17 ). These differences are not evidently correlated with coloration. The females are 4.4–6.6 mm long (mean 5.4 mm, SD 0.52 mm, n=68); there is no evidence for different size classes in the sample, but this may be sampling error (the holotype is reported as 8.5 mm long). As for some other mutillids (see, e.g., Nonveiller 1959: 114, 1980: 123), there is evidence that some specimens developed in cells or cocoons which were too small to permit full expansion of the body. This results in a squashed appearance (form “curtiventris” of Nonveiller), with the body regions proportionately shorter and broader than usual, and therefore differently shaped (compare the shapes of the head, mesosoma and T 2 in Figs 15 and 19 , for example).

Distribution. Argentina: Corrientes, Buenos Aires, Cordoba ( Casal 1963, Fritz 1998), Jujuy (first record); Uruguay (first record of the genus and species).

Comments. The sex association is based on two associated pairs of specimens collected with many others of both sexes in a limited bare area at Huacalera within a few hours. One pair was collected in copula and the male of the other pair was pursuing the female on the ground. The two females are essentially identical, but the two associated males differ in the coloration of the metasoma; one has T2 and T3 orange and the other has the metasoma entirely black.

The presence of such a large number of specimens of both sexes in a limited area suggests that this species is a parasitoid of an aggregating host; although potential hosts were not observed at the locality, many species of Halictinae occur in aggregations and it is perhaps likely that one or more halictine species are involved, as for L. parana sp. nov. (see below) and several other pseudomethocine mutillids ( Brothers et al. 2000).

The larger male specimen in AMNH has many grains of pollen on the hypostoma and a few more on the meso and metasoma. The pollen ( Fig. 14 ) was identified as belonging to the tribe Heliantheae ( Asteraceae ), and its presence suggests the utilization of an asteraceous plant as a food source for L. leguera . None of the other specimens carries such pollen, however.

Figures

FIGURES 5 – 14. Lynchiatilla spp., males. 5 – 6. Forewing. 5. L. parana sp. nov.; 6. L. tacana Casal. 7 – 9. Metasoma. 7. L. parana sp. nov. dorsal view; 8. L. parana sp. nov. hypopygium, ventral view; 9. L. tacana Casal, dorsal view. 10 – 13. Genitalia. 10 – 12. L. parana sp. nov. 10. Left side, lateral view, basal ring omitted, c = cuspis, p = paramere; 11. Volsella, lateral view, c = cuspis, d = digitus; 12. Penis valve, lateral view, 13. L. leguera Casal, penis valve, lateral view. 14. Pollen grain of tribe Heliantheae (Asteraceae) found on L. leguera Casal. Scales: 5 – 9 = 1 mm, 10 – 13 = 0.1 mm.

FIGURES 15 – 22. Lynchiatilla leguera Casal, specimens collected at same time at Huacalera, Argentina. 15 – 19. Females, showing variation in coloration, pubescent markings and body form. 15, 16. Specimen with palest coloration, largest pubescent spots and slenderest form; 17, 18. Specimen with darkest coloration (except for head), smallest pubescent spots and intermediate form; 19. Specimen with intermediate coloration, large pubescent spots and “ curtiventris ” form. 20 – 22. Males. 20. Wings. 21. Specimen with T 2 – T 4 orange, apical terga darker; 22. Specimen with metasoma entirely black. Scales = 1 mm.