Overbeckia Viehmeyer 1916
Creators: name: Klimeš, Petr
name: Drescher, Jochen
name: Buchori, Damayanti
name: Hidayat, Purnama
name: Nazarreta, Rizky
name: Potocký, Pavel
name: Rimandai, Maling
name: Scheu, Stefan
name: Matos-Maraví, Pável
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Overbeckia

description: Genus <i>Overbeckia</i> Viehmeyer (Fig. 1 <i>–</i> 6) The diagnosis based on workers (for males and queens, see descriptions). External morphology <i>Body length</i>. 4–5 mm (min. to max. WL = 1.24–2.02, WL mean = 1.68 mm). No dimorphism or apparent polymorphism in workers. <i>Head.</i> 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 <i>h</i>); scape curved and widened apically (Fig. 1 <i>b</i>, 2 <i>h</i>). 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 <i>a</i>). Head in frontal view oval, with HL similar to HW (min. to max. CI = 94–105, CI mean = 101) (Fig. 1 <i>b</i>). 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 <i>d</i>). Frontal carinae well developed, going from clypeal margin up to the middle of the head (Fig. 1 <i>d</i>) and forming a convex lifted ridge between each carina and the antennal socket apparent at lateral view (Fig. 1 <i>a</i>); vertical groove in the middle of frons between carinae missing (Fig. 1 <i>d</i>) or only outlined by a glossy smooth line (Fig. 5 <i>d</i>). 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 <i>b</i>). Workers without ocelli. <i>Mesosoma.</i> Mesosoma shape resembles that of the genus <i>Calomyrmex</i>, 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 <i>a</i>). 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 <i>c</i>). <i>Metasoma.</i> Petiole squamiform and triangular, with sharp apex in lateral view and of relatively broad lentil-shape in dorsal view (Fig. 1 <i>c</i>); a characteristic subpetiolar process present and divided from petiole node by a ridge (Fig. 1 <i>a</i>, <i>c</i>). Petiolar and propodeal spiracle with light-coloured margins. Metapleural gland vestigial, probably not functional according to Heterick (2019). <i>Sculpture.</i> 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. <i>Pilosity.</i> 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 <i>Calomyrmex</i> lacking a dense cover of long, erect hairs over thorax and legs. <i>Colouration.</i> 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 <i>a</i>, 2 <i>g</i>, 4 <i>a</i>, 5 <i>a</i>). Internal morphology: proventriculus in <i>Overbeckia v. other Camponotini</i> 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 <i>Paraparatrechina</i>. These short sepals have been noted as a main feature to distinguish <i>Overbeckia</i> from other SE Asian Formicinae genera (Bolton 1994). Our dissection conforms to the original drawing of <i>Overbeckia</i> ’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 <i>Overbeckia</i>, when compared to the other examined genera (Fig. 3 <i>a</i>). Our dissections of <i>Echinopla</i> also show sepals not much longer than the valve (Fig. 3 <i>c</i>), resembling the proventriculus of <i>Overbeckia</i>, but with softer and thinner walls (brittle structure). In contrast to <i>Overbeckia</i> and <i>Echinopla</i>, <i>Calomyrmex</i> has sepals approximately twice as long as the valve, similar to <i>Opisthopsis</i> (i.e. ‘ <i>Formica</i> ’ type in Eisner 1957; Fig. 3 <i>b</i>). <i>Colobopsis</i> resembles <i>Camponotus</i> in the long sepals, more than 2.5× longer than the valve (i.e. ‘ <i>Camponotus</i> ’ type that also occurs in <i>Polyrhachis</i> (Eisner 1957; Fig. 3 <i>d</i>).
description: Published as part of <i>Klimeš, Petr, Drescher, Jochen, Buchori, Damayanti, Hidayat, Purnama, Nazarreta, Rizky, Potocký, Pavel, Rimandai, Maling, Scheu, Stefan &amp; Matos-Maraví, Pável, 2022, Uncovering cryptic diversity in the enigmatic ant genus Overbeckia and insights into the phylogeny of Camponotini (Hymenoptera: Formicidae: Formicinae), pp. 277-288 in Invertebrate Systematics 36 (6)</i> on pages 562-563, DOI: 10.1071/is21067, http://zenodo.org/record/6987297
description: {"references": ["Heterick BE (2019) First record of the formicine genus Overbeckia (Hymenoptera: Formicidae) from Australia. Myrmecological News 29, 163 - 166.", "Viehmeyer H (1916) Ameisen von Singapore. Beobachtet und gesammelt von H. Overbeck. Archiv fur Naturgeschichte - A 81 (8), 108 - 168.", "Bolton B (1994) ' Identification guide to the ant genera of the world. ' (Harvard University Press: Cambridge, MA, USA)", "Eisner T (1957) A comparative morphological study of the proventriculus of ants (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology at Harvard College 116, 439 - 490."]}