Horismenus depressoides Hansson & Kenyon & Benrey 2019, sp. nov.

Horismenus depressoides sp. nov.

Figs 5–8, 9–12, 13, 15

Diagnosis. Antennal scrobes join below frontal suture (Figs 9, 10); female flagellomeres short and stout (Fig. 7), e.g. 1 st flagellomere 2.4× as long as wide; male scape 3.7× as long as wide (Fig. 8); forewing speculum open below; scutellum flat with posteromedian part smooth and shiny (Fig. 12); propodeum with median carina with sides rounded and converging towards posterior part, and with anterior part blunt (Figs 12, 13); first gastral tergite with posterior ¾ with punctures. Very similar to H. depressus but differs in having a larger propodeal spiracle (Fig. 13), female gaster with apex distinctly more blunt (Fig. 15), and entire thoracic dorsum bright metallic bluish-green (Fig. 6), with or without purple tinges.

Description. FEMALE. Length 2.0– 2.1 mm. Scape yellowish-white with apical ¼ metallic bluish-green; pedicel and flagellum metallic bluish-green. Frons metallic bluish-green. Vertex metallic bluish-green. Mesosoma metallic bluish-green with purple tinges, propodeum with smooth parts metallic bluish-green, reticulate parts metallic dark purple. Coxae metallic bluish-green; femora, tibiae and tarsi yellowish-white. Wings hyaline. Petiole metallic dark purple. Gaster with first tergite metallic bluish-green in anterior ⅓, metallic dark purple in posterior ¾; remaining tergites metallic dark purple.

Antenna as in Fig. 7. Frons with interscrobal area smooth, clypeal area and part just above frontal suture with raised and weak reticulation, remaining parts with raised and strong reticulation; frontal suture V-shaped, incomplete not reaching eyes; antennal scrobes join below frontal suture. Vertex with engraved and strong reticulation; with a median groove in posterior part, groove continues down on occiput. Occipital margin rounded.

Mesoscutum with raised and strong reticulation, midlobe with posteromedian ¼ with engraved reticulation; notauli as narrow and distinct grooves medially. Scutellum flat, with engraved and weak reticulation, partly to predominantly smooth. Dorsellum smooth, anterolaterally with two large foveae. Coxae smooth and shiny. Propodeum smooth and shiny, submedian grooves reticulate; propodeal callus with 2–3 setae. Forewing speculum open below; with 12–13 admarginal setae.

Gaster with first tergite smooth and shiny in anterior ⅓, posterior ¾ with punctures.

Ratios. DE/DO 5.0; WH/DE 2.1; HE/MS/WM 3.6/1.0/2.2; POL/OOL/POO 8.3/2.8/1.0; WH/WT 1.1; LW/ LM/HW 1.7/1.0/1.0; PM/ST 0.8; LC/WC 3.9; WG/WC 0.5; LS/LT 0.21; LP/WP 1.1; MM/LG 1.1.

MALE. Length 1.9–2.1 mm. Frons metallic purple. Vertex golden-green. Colour otherwise as in female. Antenna as in Fig. 8. Head and mesosoma as in female.

Ratios. HE/MS/WM 3.2/1.0/2.0; LP/WP 1.4; MM/LG 1.2.

Distribution. Honduras, Mexico.

Hosts. Larvae of Acanthoscelides obtectus and Acanthoscelides sp. (Coleoptera: Chrysomelidae: Bruchinae) on Phaseolus vulgaris (Fabaceae).

Type material. Holotype female labelled “ MEXICO, Est. Mexico, Temascaltepec, 100°02'730''W 19°02'584''N, 1750 m, 21.xii.2001 - 2.iii.2002, A. Aebi ”, “Ex Acanthoscelides sp. on Phaseolus vulgaris ”, in MZLU. Paratypes. 22♀ and 22♂ mounted on cards (in MZLU & NHM). HONDURAS. Francisco Morazán: San Antonio de Oriente, El Zamorano, 8.ii.1990, L. Vazquez, from larva of Acanthoscelides obtectus on Phaseolus vulgaris (6♀ 6♂). Mexico: with same label data as holotype (3♀ 4♂), and from same locality and same host but collected 16.xii.2001 - 3.ii.2002 (1♀ 2♂); Valle de Bravo, 100°08'985''W 18°55'85''N, 1950 m, 1.i-15.ii.2002, A. Aebi, from Acantoscelides sp. on Phaseolus vulgaris (1♀ 1♂); Tejupilco, 99°07'270''W 18°59'603''N, 1400 m, 21.xii.2001 - 2.ii.2002, A. Aebi, from Acanthoscelides sp. on Phaseolus vulgaris (5♀ 3♂). Michoacan: Paso Real, 101°44'359''W 19°06'769''N, 1490 m, 10.ii.2002, A.Aebi (1♀ 2♂): Morelos: San José de los Laureles, 99°00'005''W 18°58'497''N, 1855 m, 19.xii.2001 - 3.ii.2002, A. Aebi, from Acanthoscelides sp. on Phaseolus vulgaris (1♀ 1♂), and from same locality and same host but collected 5.i-23.ii.2003 (4♀ 4♂); Tepoztlan, 99°07'2705''W 18°59'603''N, 1870 m, 16.xii.2001 - 3.ii.2002, A. Aebi, from Acanthoscelides sp. on Phaseolus vulgaris (2♀ 1♂), 5♀ 7♂ from same locality as previous, from A. obtectus and collected 31.iii.1980.

Etymology. Named after similarity to H. depressus, with the Greek suffix - eides = like.

Molecular data. Horismenus depressoides equals “HD3” in Kenyon et al. (2015) and molecular data associated with “HD3” is accounted for in that paper.

Remarks. H. depressoides is very similar to H. depressus and has previously been mixed-up with this species (Hansson et al. 2004, Hansson 2009). Due to the difficulty in separating these two species the distributional and biological records presented here include only specimens that have been examined for this manuscript.