Balleriolus howdeni, Sousa & Vaz-de-Mello, 2023

Sousa, Rafael & Vaz-de-Mello, Fernando Z., 2023, Balleriolus, a new termitophilous genus of Ceratocanthinae (Coleoptera: Hybosoridae) from South America and notes on termitophily in the tribe Scarabatermitini, Journal of Natural History 57 (29 - 32), pp. 1377-1395 : 1386-1389

Balleriolus howdeni sp. n.

( Figures 1A–D, M, 2, 3 H, 4 B, F, J, M, N, 5B, C)

Differential diagnosis. See B. alleni sp. n. (below).

Description. Holotype. Male. Body. Length 4.5 mm; width across posterior margin of pronotum 1.5 mm. Colour. Dorsal surface dark reddish brown; ventral surface, antennae, mouthparts and legs light reddish yellow, except the protibia, slightly darker, setae yellow ( Figure 1A–C, E–H, M). Head. Surface of frons glabrous; disc slightly convex; eye-canthus slightly angulated, extending about half length of eye; clypeal disc glabrous, anterior margin slightly reflexed, emarginated in median area and with 3 setae on each side ( Figures 1A–C, M, 4B). Labrum transverse and membranous, disc convex, anterior margin slightly rounded and with a long lateral seta on each side ( Figure 1M). Mandibles with a long seta on anterior area of outer face, inner margin slightly sinuated, tooth rounded ( Figure 1M). Maxilla with galea inwards projected and with long and light-yellow brushlike setae ( Figure 3H); distal palpomere flattened ( Figures 1M, 3H, 4B). Mentum small and slightly convex. Antennal scape outwardly expanded ( Figures 3H, 4B); club oval and laterally setose, dorsal surface of distal lamella tomentose anteriorly ( Figures 3H, 4B). Thorax. Surface of pronotum glabrous, slightly shiny and with micro punctures; anterior median half strongly convex, converging anteriorly; posterior angles rounded and divergent; lateral area concave on each side extending almost to anterior and posterior angles; outer anterior area of sulcus slightly emarginated, anterior angles distinct; pronotal scar distinct; pseudoscutellum rounded and strongly convex, posterior margin rounded ( Figures 1A–C, E–H, M, 4B). Hypomeron glabrous ( Figure 3H). Prosternal anterior margin setose. Scutellum almost as wide as the posterior area of pseudoscutellum; posterior area narrow and acute ( Figure 1A). Elytral surface with 3 weakly marked striae in the anterior half; disc rounded; distal angle rounded; limit between pseudoepipleure and elytron with 7 long setae; posterior area near to distal angles with a slight depression ( Figures 1A–C, E–H, 2 A, 4F). Mesoventrite glabrous. Metaventrite with sparse setae posteriorly; posterior margin sinuated. Legs. Procoxa with setae on median area of outer face and on distal area of inner face ( Figure 3H). Profemur with small and sparse setae laterally and a fringe of long setae on proximal area of inner face ( Figure 3H). Outer face of protibia with setigerous punctures, setae short and erect; outer margin with long and sparse setae; inner margin with setae only on distal area ( Figure 4J). Meso- and metafemora with setigerous punctures with setae short and erect on ventral surface and long and sparse setae distributed laterally. Metathoracic wings large. Abdomen. Surface of 6 visible sternites with long and scattered setae ( Figure 1F). Terminalia. Aedeagus with parameres narrow, laterally depressive, poorly sclerotised, sinuous in the apex and lightly separated from each other. Median lobe indistinct ( Figure 3M, N).

Type material. Holotype: J ( CEMT); BRAZIL: Distrito Federal., Planaltina. Embrapa CPAC, 15.605528°S, 47.707056°W, 1001 m. Armadilha queda, 24 August 2005. C.M. Olivera; Projeto FAPD /DF – CNPq, Biodiversidade / Entomológica, Cerrado – 2005/2006, Fitofisionomia: Cerradão, Coll. Charles Martins Oliveira; holotype; Balleriolus howdeni sp. n.; des. Sousa and Vaz-de-Mello 2021 . Paratypes: BRAZIL: Distrito Federal: same as holotype (1 J CEMT); Minas Gerais: BRAZIL: M .G. Lavras, C /M M3-B 15 August 2002, Project . Fragm. Entom. ( 2 ♀ CEMT, 1 ♀ MZSP 22060 ) ; BRAZIL: M.G. Lavras, C /M B3-B 15 August 2002, Proj . Fragm. Entom. ( 1 ♀ CEMT, 1 ♀ ABPC) ; BRAZIL: M.G. Lavras, C /M M5-B 28 August 2002, Proj . Fragm. Entom. ( 1 ♀ CEMT) ; Brazil: M.G., Nova Lima, Caverna: RM _0038, Coord . 606874/7786748 20.013472°S, 43.978639°W, Alt . 1, 357 m – Parcela 18, Data: 04 September 2016, Coll . Zampaulo R .A.; Reis, A.S. ( 1 ♀ CEMT) .

Paratypes are labelled as ̍ PARATYPE; Balleriolus howdeni sp. n.; des. Sousa & Vaz-de-Mello 2022 [handwritten]′.

Distribution. Brazil: Minas Gerais (Lavras, Nova Lima), Brasília ( Figures 5A, 6A). Etymology. The species is named to honour the memory of the great scarabaeoid researcher Dr Henry F. Howden.

Physogastric and intermediate forms. Metathoracic wings large, broken on the base in the studied physogastric specimen. Abdomen greatly expanded (intermediate forms are more compact, Figures 2, 5B, C), tergites V–VIII dorsally visible, densely setose (setae long and erected) and with sclerotised plates in the median dorsal area ( Figure 2). Pygidium with disc membranous, posterior half setose, margin very sclerotised ( Figure 2A). Sternites densely setose on the anterior half. Abdominal spiracles IV– VIII visible in lateral view. Terminalia. Paraprocts elongated and slightly rectangular ( Figure 2D, E). Gonocoxite divided into 3 pieces; proximal piece covers all lateral area, with long and erected setae in the distal area; median piece with setae in distal margin; distal piece elongated, slightly setose, emarginated medially with divergent angles; gonostylus indistinct ( Figure 2D, E).

Biology. The physogastric female was collected in the soil, near a termite gallery, alongside workers of Apicotermitinae (Isoptera: Termitidae ) and near soldiers of Nasutitermes sp. ( Termitidae : Nasutitermitinae ) in an aphotic zone, inside a cave at Parque Estadual da Serra do Rola Moça (Nova Lima, Minas Gerais State) ( Figure 5). However, it was not possible to specify which (if any) of these termite species belonged to the gallery.

Remarks. Some paratypes have morphological variations in body colour (dark reddish brown), and the shape of pronotum (less rounded anteriorly and lateral margin slightly sinuated in median area). Some setae of the clypeus and elytra were not observed in the holotype (probably broken), only in the paratypes. Studies on genera of Scarabatermitini describe very superficial sexual dimorphism among the species of the tribe (eg Silvestri 1940; Howden 1973; Howden and Gill 1988a, 1995, 2000); otherwise, the sexual dimorphism of Balleriolus is restricted to terminalia.