Hypoponera angustata (Santschi)

Bolton, B. & Fisher, B. L., 2011, Taxonomy of Afrotropical and West Palaearctic ants of the ponerine genus Hypoponera Santschi (Hymenoptera: Formicidae)., Zootaxa 2843, pp. 1-118 : 24-26

Hypoponera angustata (Santschi) (Figs 1 – 3)

Cryptopone angustata Santschi , 1914b: 319, fig. 7. Syntype workers, GUINEA: Kakulima, 1913 (F. Silvestri), and GUINEA: Mamou (F. Silvestri) (NHMB) [examined]. [Combination in Pseudocryptopone: Santschi, 1937b: 366; in Ponera : Brown, 1963: 6; in Hypoponera : Taylor, 1967: 12.]

WORKER. Measurements: HL 0.38 – 0.45, HW 0.27 – 0.35, HS 0.320 – 0.390, SL 0.20 – 0.26, PrW 0.19 – 0.25, WL 0.45 – 0.54, HFL 0.18 – 0.23, PeNL 0.11 – 0.14, PeH 0.18 – 0.22, PeNW 0.12 – 0.15, PeS 0.140 – 0.167 (28 measured). Indices: CI 72 – 78, SI 71 – 79, PeNI 56 – 70, LPeI 55 – 70, DPeI 100 – 125.

Minute species. Eyes absent. Scape very short; when laid straight back from its insertion the apex falls far short of the midpoint of the posterior margin in full-face view; SL/HL 0.53 – 0.60. Funiculus of antenna conspicuously with only four enlarged segments apically. Cephalic dorsum minutely reticulate-punctate. Mesonotal-mesopleural suture absent; fine pubescence of mesonotum ends at line where the suture would be expected to run. Dorsum of mesosoma without trace of a metanotal groove. Propodeal declivity narrow; declivity rounds into the sides through a blunt angle, without a carina or sharp margin separating them. Pronotal dorsum with very weak, superficial punctulate sculpture, much weaker and less dense than on the head. Petiole node in dorsal view as broad as long or only slightly broader than long (DPeI 125 at maximum); anterior face of node bluntly rounded, the sides usually very weakly divergent posteriorly. Posterior surface of node without cuticular ridges radiating from the peduncle, but usually with a fine transverse carina just above the peduncle. Petiole node in profile low and relatively long, with a weakly convex dorsum. Anterior and posterior faces of node usually very weakly convergent dorsally, but sometimes almost parallel. Subpetiolar process usually with a simple angle in the ventral margin of the sternite, but the angle may vary from distinct to very rounded and inconspicuous. In dorsal view the maximum width of the first tergite is less than the width of the second tergite at its midlength. Base of cinctus of second gastral tergite is sculptured with a dense row of very short longitudinal cross-ribs that may appear as a row of adjacent punctures with raised margins between them. Sides of second gastral tergite shallowly convex in dorsal view; midline length of second gastral posttergite, from posterior margin of cinctus to apex, is less than the maximum width of the segment. Disc of second gastral tergite microreticulate or with superficial reticulate-punctate sculpture. Dorsal surfaces of body with short but quite distinct pubescence, and with numerous very short projecting setae. Full adult colour yellow.

A very distinctive and widely distributed minute species that occurs in leaf litter and rotten wood throughout the forest zones of west, central and east Africa. Immediately obvious in angustata is the clearly differentiated 4- segmented antennal club, with funiculus segment 7 extremely reduced compared to segment 8 and scarcely larger than segment 6. This is the only known Afrotropical species with a differentiated club, all others have the funiculus more or less obviously gradually incrassate towards the apex, the incrassation involving 5 or 6 segments. Similar in appearance to angustata is perparva , but the latter has the antenna gradually incrassate apically, with a vaguely 5- segmented club (i.e. funiculus segment 7 is smaller than 8, but distinctly larger than segment 6), and in profile has the anterior and posterior faces of the node strongly convergent dorsally. Both species are small to minute (HW 0.27 – 0.35, SL 0.20 – 0.26) and are characterised together within section 1 of the abeillei group by having relatively short scapes, relatively long narrow petiole nodes in dorsal view and relatively long low petiole nodes in profile, i.e. low SI and DPeI combined with high LPeI. These ranges are not completely exclusive, as individuals from some other species overlap their ends, but in general the other species have relatively longer scapes, relatively shorter and broader petiole nodes in dorsal view, and relatively shorter, higher petiole nodes in profile. The species angustata and perparva together have the ranges SI 71 – 81 (SL/HL 0.53 – 0.60), DPeI 100 – 125 and LPeI 52 – 70. In the remaining species of the section the combined range of SI is 75 – 92 (SL/HL 0.60 – 0.73), with only very few specimens having relatively short scapes with SI <80. DPeI in remaining species of the section is 100 – 187, but only bulawayensis (DPeI 110), regis (DPeI 100), some specimens of blanda (minimum DPeI 120) and some workers of inaudax and coeca (lowest DPeI 125) overlap the range of angustata and perparva .

Material examined. Guinea: Kakulima (F. Silvestri); Mamou (F. Silvestri). Ivory Coast: Abidjan, Adiopodoume(I. Löbl), Abidjan, Banco Nat. Pk (I. Löbl), Agboville, Yapo-Gare (I. Löbl), Iringou (F. K r e ll), Tai Forest (V. Mahnert). Ghana: Tafo (D. Leston), Tafo (R. Belshaw), Mampong (P. M. R o o m), Efiduase (R. Belshaw), Poano (R. Belshaw), Esunkawkaw (R. Belshaw), Sui For. Res. (R. Belshaw), Sagymasi (R. Belshaw), Kade (R. Belshaw), Bunso (R. Belshaw). Nigeria: Ile-Ife (J.T. Medler). Cameroun: Mbalmayo (N. Stork), Prov. Sud-Ouest, Bimbia For., Limbe (B.L. Fisher), Prov. Sud-Ouest, Korup, Mundemba (B.L. Fisher), Prov. Sud, Res. Campo, Massif des Mamelles (B.L. Fisher), Prov. Sud, PN Campo, Campo (B.L. Fisher), Prov. Sud, Res. de Faune de Campo (B.L. Fisher), Prov. Sud, N’kolo, Bondé For., Elogbatindi (B.L. Fisher). Gabon: Prov. Ogooue-Maritime, Res. Moukalaba, Doussala (B.L. Fisher), Prov. Ogooue-Maritime, Res. Monts Doudou (B.L. Fisher), Prov. Estuaire, FC Mondah, NNW Libreville (B.L. Fisher), Prov. Estuaire, Pointe Ngombe, Ekwata (B.L. Fisher), Prov. Woleu-Ntem, ESE Minvoul (B.L. Fisher). Central African Republic: PN Dzanga-Ndoki, Lidjombo (B.L. Fisher), Res. Dzanga-Sangha, Bayanga (B.L. Fisher). Rwanda: Rangiro (P. W e r n e r). Uganda: Kalinzu N.P. (M. Kiyono). Kenya: Western Prov., Kakamega For., Buyangu (G. F is c h e r); Kakamega For., Ngavira (F. Hita Garcia); Kakamega Distr., Yala River Nat. Res. (Snelling & Espira); Nakuru, Lake Naivasha (Mahnert & Perret); Lamu, nr Witu (Mahnert & Perret); Lake Nakuru Nat. Pk (V. M a h n e r t); Kisumu Chemelil (V. Mahnert).