Uncovering cryptic diversity in the enigmatic ant genus Overbeckia and insights into the phylogeny of Camponotini (Hymenoptera: Formicidae: Formicinae) Author Klimeš, Petr Biology Centre of the Czech Academy of Sciences, Institute of Entomology, BraniŠovská 31, CZ- 370 05 České Budějovice, Czech Republic Author Drescher, Jochen Department of Animal Ecology, University of Göttingen, J. - F. - Blumenbach Institute for Zoology & Anthropology, Untere Karspüle 2, D- 37073 Göttingen, Germany Author Buchori, Damayanti Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University, Jl. Kamper, Kampus IPB Dramaga, Bogor 16680, Indonesia Author Hidayat, Purnama Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University, Jl. Kamper, Kampus IPB Dramaga, Bogor 16680, Indonesia Author Nazarreta, Rizky Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University, Jl. Kamper, Kampus IPB Dramaga, Bogor 16680, Indonesia Author Potocký, Pavel Biology Centre of the Czech Academy of Sciences, Institute of Entomology, BraniŠovská 31, CZ- 370 05 České Budějovice, Czech Republic Author Rimandai, Maling New Guinea Binatang Research Center, PO Box 604, Madang, Papua New Guinea Author Scheu, Stefan Department of Animal Ecology, University of Göttingen, J. - F. - Blumenbach Institute for Zoology & Anthropology, Untere Karspüle 2, D- 37073 Göttingen, Germany & Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Büsgenweg 1, D- 37077 Göttingen, Germany Author Matos-Maraví, Pável Biology Centre of the Czech Academy of Sciences, Institute of Entomology, BraniŠovská 31, CZ- 370 05 České Budějovice, Czech Republic text Invertebrate Systematics 2022 2022-07-25 36 6 277 288 http://dx.doi.org/10.1071/is21067 journal article 10.1071/is21067 8c0715c9-57f5-40db-8c48-99bf3719eedb 6987297 Genus Overbeckia Viehmeyer ( Fig. 1 – 6 ) The diagnosis based on workers (for males and queens, see descriptions). External morphology Body length . 4–5 mm (min. to max. WL = 1.24–2.02, WL mean = 1.68 mm ). No dimorphism or apparent polymorphism in workers. Head. 12-segmented antennae including scape, without distinct club but with funicular segments continuously enlarged towards the tip, with distal flagellomere approximately twice as wide as the basal flagellomere ( Fig. 2 h ); scape curved and widened apically ( Fig. 1 b , 2 h ). Antennal socket relatively closer to the posterior margin of clypeus than in other Camponotini . Palp formula 6: 4, with apical segment of maxillary palp 15–20% shorter than the subapical segment ( Fig. 5 a ). Head in frontal view oval, with HL similar to HW (min. to max. CI = 94–105, CI mean = 101) ( Fig. 1 b ). Clypeus slightly convex anteriorly and posterior clypeal margin incised in the middle by a developed suture, forming the frontal triangle; but the posterior suture of the triangle below carinae not developed, rather only outlined by bent cuticle ( Fig. 1 d ). Frontal carinae well developed, going from clypeal margin up to the middle of the head ( Fig. 1 d ) and forming a convex lifted ridge between each carina and the antennal socket apparent at lateral view ( Fig. 1 a ); vertical groove in the middle of frons between carinae missing ( Fig. 1 d ) or only outlined by a glossy smooth line ( Fig. 5 d ). Mandibles triangular with five teeth that decrease in size from apical to basal teeth. Eyes relatively large (min. to max. EL = 0.25–0.40 mm , mean EL = 0.32) and placed vertically in the middle of the head, surpassing the head margins in frontal view, with ~20 ommatidia in the longest axis ( Fig. 1 b ). Workers without ocelli. Mesosoma. Mesosoma shape resembles that of the genus Calomyrmex , with a well developed promesonotal suture. Metanotal groove limited at most of the length to the dorsum of thorax and ending laterally next to the metathoracic spiracle, with a depression and smooth area around the spiracle ( Fig. 1 a ). The depression next to metathoracic spiracle region is also well visible in dorsal view, with propodeum laterally constricted compared to relatively broad pronotum ( Fig. 1 c ). Fig. 1. Overbeckia subclavata , non-type. Worker from Indonesia (specimen HJ.3.1) displaying the lateral ( a ), frontal ( b ) and dorsal ( c ) views. Detail of head sculpture and shape of frontal carinae ( d ). Note hind leg tibia and tarsi are missing (damaged). Metasoma. Petiole squamiform and triangular, with sharp apex in lateral view and of relatively broad lentil-shape in dorsal view ( Fig. 1 c ); a characteristic subpetiolar process present and divided from petiole node by a ridge ( Fig. 1 a , c ). Petiolar and propodeal spiracle with light-coloured margins. Metapleural gland vestigial, probably not functional according to Heterick (2019) . Sculpture. On whole body, cuticle relatively smooth and glossy, with only fine punctation or soft lineation. No spines on thorax and petiole, and no deep wrinkles and pits present. Pilosity. Rather short, appressed pilosity; a few longer erect hairs present however at least at the scape apex, on ventral head, abdomen and clypeus (hair length ≤ EL ); in contrast to Calomyrmex lacking a dense cover of long, erect hairs over thorax and legs. Colouration. Head, mesosoma and petiole dark brown to blackish colour, abdomen and appendages rather lighter (brown to light brown) and with yellowish coxae and trochanters; except frontal coxa that are darker, similar in colour to thorax ( Fig. 1 a , 2 g , 4 a , 5 a ). Internal morphology: proventriculus in Overbeckia v. other Camponotini genera Viehmeyer (1916) provided a drawing of the proventriculus in the original genus description, in which rather short sepals were described, being slightly bent anteriorly and of a similar length to the vertical length of the valve (i.e. ‘the stomach pump’), resembling in this respect the genus Paraparatrechina . These short sepals have been noted as a main feature to distinguish Overbeckia from other SE Asian Formicinae genera ( Bolton 1994 ). Our dissection conforms to the original drawing of Overbeckia ’s proventriculus by Viehmeyer (1916) , showing a similar proportion of sepals compared to the valve. Furthermore, we observed that the valve has relatively thicker walls of whitish colour in Overbeckia , when compared to the other examined genera ( Fig. 3 a ). Our dissections of Echinopla also show sepals not much longer than the valve ( Fig. 3 c ), resembling the proventriculus of Overbeckia , but with softer and thinner walls (brittle structure). In contrast to Overbeckia and Echinopla , Calomyrmex has sepals approximately twice as long as the valve, similar to Opisthopsis (i.e. ‘ Formica ’ type in Eisner 1957 ; Fig. 3 b ). Colobopsis resembles Camponotus in the long sepals, more than 2.5× longer than the valve (i.e. ‘ Camponotus ’ type that also occurs in Polyrhachis ( Eisner 1957 ; Fig. 3 d ).