Hypoponera dulcis (Forel)

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 : 43-46

Hypoponera dulcis (Forel)

(Figs 34 – 36)

Ponera dulcis Forel , 1907a: 2. Holotype worker, TANZANIA: Arusha-chini (Katona) (not in MHNG, presumed lost.) [Combination in Hypoponera : Bolton, 1995: 214.] (See note 1.)

Ponera dulcis var. uncta Santschi , 1914c: 7. Holotype worker, SOUTH AFRICA: Zululand, Dukudu, dans la mousse, 27.vii.05 (I. Trågärdh) (not in NHMB, presumed lost). Syn. n. [Combination in Hypoponera : Bolton, 1995: 216.] (See note 2.)

Ponera rothkirchi Wasmann , 1918: 145. Holotype worker, CAMEROUN: Kamerunburg, Soppo, 730 m., xii.1912 (von Rothkirch) (NHMM) [not examined directly]. Syn. n. [Combination in Hypoponera : Bolton, 1995: 216.] (See note 3.)

Ponera lotti Weber , 1942: 45, fig. 5. Syntype workers, SUDAN: Imatong Mts, Equatoria, Lotti Forest, 24.vii. - 5.viii.1939, nos. 1442, 1448 (N.A. Weber) (MCZC) [examined]. Syn. n. [Combination in Hypoponera : Bolton, 1995: 215.]

Ponera muscicola Weber , 1942: 45, fig. 13. Holotype queen, SUDAN: Imatong Mts, 25.vii.1939, 7200 ft, no. 1313, in wet moss in cavity of a tree (N.A. Weber) (not in MCZC, presumed lost). Syn. n. [Combination in Hypoponera : Bolton, 1995: 215.] (See note 4.)

Ponera lamottei Bernard , 1953: 204, fig. 3B. Syntype workers, GUINEA: Nion, 700 m., 15.iv., st. 22 (Lamotte) (MNHN) [examined]. Syn. n. [Combination in Hypoponera : Bolton, 1995: 215.]

Ponera mandibularis Bernard , 1953: 205, fig. 3F. LECTOTYPE worker (teneral) (by present designation), GUINEA: Nimba (Lamotte) (MNHN) [examined]. Syn. n. [Combination in Hypoponera : Bolton, 1995: 215.] (See note 5.)

Ponera (Hypoponera) villiersi Bernard , 1953: 206, fig. 3G. Holotype worker (teneral), GUINEA: N.-E. du Nimba, mousses de la forêt (Villiers) (MNHN) [examined]. Syn. n. [Combination in Hypoponera : Bolton, 1995: 216.] (See note 6.)

NOTES.

1 Dr Bernhard Merz (MHNG) informs us that the holotype of dulcis is missing from the Forel collection. He says that there are three empty pin-holes in the Forel collection under this name, one of which was presumably the holotype. Fortunately three specimens so identified by Forel remain; they are conspecific and indicate exactly what Forel regarded as dulcis : one worker each from South Africa (Durban), Zimbabwe (Bulawayo) and Eritrea (Nefasit). Designation of a neotype was considered but rejected because there is a chance that the holotype may eventually be found and there is no doubt about what Forel considered the species to be.

2 The holotype of uncta is missing from the NHMB collection. However, Santschi does not cite any characters that would isolate uncta or separate it from dulcis . The dentition he describes is extremely common in dulcis but not elsewhere and his description is an adequate match with Forel’s South Africa specimen. Together, this information seems sufficient to place var. uncta safely in synonymy here.

3 Dr Paul Beuk (NHMM) kindly sent several photographs of the holotype of rothkirchi and answered a series of questions concerning details of its morphology, confirming the synonymy of this name under dulcis . The synonymy was previously suspected from Wasmann’s original description and the sketches of the holotype made later by Santschi (1926: 208, fig. 1A,B). In Santschi’s drawing of the head in full-face view, fig. 1A, small eyes are indicated, but these are omitted from the profile view that is his fig. 1B. In view of their presence in fig. 1A, and of Wasmann’s statement that the holotype has “ sehr deutliche kleine Augenpunkte ”, confirmed by Dr Beuk’s photographs, it seems reasonable to assume that Santschi’s omission of eyes from his fig. 1B was an oversight.

4 We are informed by Stefan Cover that although the holotype of muscicola is registered as present in MCZC the specimen is missing from the collection and cannot be found. However, Weber’s description, and his drawing of the petiole, make it reasonably certain that the specimen was a queen of dulcis .

5 Bernard’s original syntype series for mandibularis included one worker and one queen from Guinea: Nimba (Lamotte) as “types”, and one worker and one queen from Ivory Coast: Banco (worker) and La Bé (queen) (Delamare) as “cotypes”. The two Nimba specimens are mounted on a single card rectangle. The queen has no head, is mounted upside-down and lacks most of its legs. However, the petiole node is clear of the substrate and visible; the specimen is certainly a queen of coeca or inaudax and is certainly a different species from the worker mounted on the same card, which is a teneral of dulcis . Of the two Ivory Coast specimens one, labelled Banco, 8.8.45, appears to be a queen of coeca ; the other, a worker from La Bé, was not found. Note that Bernard (1953: 205) states that the queen is from La Bé and the worker from Banco, the opposite of the data on the available label. The Nimba worker specimen is here designated as lectotype as that is the one actually described by Bernard; only the length of the queen is given, without further information. All specimens except the lectotype are hereby excluded from the type-series.

6 The head of the villiersi holotype has been lost and much of the mesosoma, petiole and gastral base are coated with glue. However, what remains is very obviously a teneral worker of dulcis . Bernard (1953: 201) runs villiersi out in his key under the section in which the metanotal groove is absent; it is present but obscured by glue.

WORKER. Measurements: HL 0.54 – 0.63, HW 0.44 – 0.52, HS 0.490 – 0.570, SL 0.41 – 0.48, PrW 0.33 – 0.39, WL 0.73 – 0.84, HFL 0.44 – 0.54, PeNL 0.11 – 0.14, PeH 0.34 – 0.39, PeNW 0.23 – 0.28, PeS 0.227 – 0.267 (60 measured). Indices: CI 77 – 84, SI 92 – 102, PeNI 60 – 76, LPeI 32 – 39, DPeI 180 – 218.

Eyes present, black, small but distinct (always very conspicuous in specimens in alcohol), of 2 – 6 small ommatidia that are variable in size. The individual ommatidia are sometimes poorly defined or even partially fused; occasionally when several ommatidia are present one may be decidedly larger than the rest. Mandible most commonly with three relatively large teeth distally that are followed proximally by a variable number of smaller teeth or denticles that are all of approximately the same size, giving the margin a roughly serrate appearance. In some, one or two teeth in the serrate row may be somewhat enlarged. Scapes relatively long, SI 92 – 102; apex of scape, when laid straight back from its insertion in full-face view, varies from just failing to reach to slightly exceeding the mid-point of the posterior margin; SL/HL 0.74 – 0.83. Reticulate-punctate sculpture on cephalic dorsum very fine, frequently superficial but denser than on the dorsal pronotum, which is almost smooth with only very widely spaced minute superficial punctulae present. Mesonotal-mesopleural suture distinct on side of mesosoma. Metanotal groove conspicuous across dorsum of mesosoma, distinctly incised; mesonotum with a well-defined posterior margin. Mesopleuron mostly to entirely smooth and shining, unsculptured except for a few scattered minute pits. With propodeum in profile the length of the dorsum may vary from slightly to distinctly shorter than the full depth of the declivity. Petiole squamiform; node in profile tall and narrow, with the anterior and posterior faces converging dorsally to a short and narrowly rounded dorsum. Subpetiolar process in profile distinct but blunt, without acute or sharply developed angles anteriorly or posteriorly. In dorsal view the petiole node much broader than long (DPeI 180 or more), the dorsal surface very short from front to back. Maximum width of first gastral tergite in dorsal view sometimes slightly greater than width of the second tergite at its midlength, but often the two are about equal. Base of cinctus of second gastral tergite smooth and shining in dorsal view, without cross-ribs. Posttergite of second gastral segment, from posterior margin of cinctus to apex, broader than long. First gastral tergite pubescent and dorsally with standing setae that vary from absent to conspicuous (see discussion below). Full adult colour varies from dull yellow to dark brown; most common shades are light brown to medium brown.

This is one of the most widely distributed and most abundant Hypoponera species throughout sub-Saharan Africa. It may be extremely numerous in leaf litter samples. For instance, in Belshaw & Bolton (1994), dulcis (recorded as H.sp.2) accounted for more than three times the number of all the other Ghanaian Hypoponera species combined. On its own dulcis represented an incredible 51% of all the Ponerini retrieved and comprised 4.2% of all the ants collected in the survey. This preponderance is also reflected in B. L. Fisher’s collections in Cameroun, Gabon and the Central African Republic (unpublished data).

As defined above, dulcis is perhaps the most easily recognised of all the Afrotropical Hypoponera . In brief, any specimen that combines the characters of eyes small but distinctly present, scapes relatively long, mesonotal-mesopleural suture (in profile) and metanotal groove (in dorsal view) both present, petiole scale-like, mesopleuron unsculptured and cinctus of second gastral tergite smooth at its base, is dulcis . However, there is some variation in the material examined that may suggest the presence of a second species within this group. In some darkly coloured specimens from Cameroun and Gabon (in BMNH and CASC), the mesonotum in profile is distinctly convex, whereas in all other material it is more or less flat. The degree of convexity varies and is sometimes difficult to assess as specimens in which the pronotum is fully flexed down with respect to the mesonotum appear more convex than those in which the two sclerites are aligned, because more of the curved anterior articulatory surface of the mesonotum is exposed. Coupled with this, the dorsum of the first gastral tergite in these workers where the mesonotum is more convex has conspicuous setae, whereas in the vast majority of specimens the setae on the first tergite are sparse and minute, and sometimes appear to be absent. The state in which the setae are reduced or absent applies to all queens examined, apparently regardless of the condition exhibited by their workers. None of the names included in the synonymic synopsis above, and none of Forel’s surviving specimens of dulcis , show either of the variations just discussed. It would perhaps be justifiable to nominate the variant forms as a separate species, but intermediates would, it is suspected, render the separation untenable. The resolution of this problem is beyond the scope of this contribution and must await individual analysis.

Variation in full adult colour seems insignificant as all intermediate shades between the lightest (dull yellow) and the darkest (dark brown) occur. No worker-queen intercaste forms have been seen in the hundreds of specimens examined, nor has any ergatoid male been detected; all queens and males seen have been fully alate.

The taxon H. lea (Santschi) may be a junior synonym of dulcis ; see the discussion under species inquirendae.

Material examined. Guinea: Nion (Lamotte); Nimba (Lamotte), N.E. Nimba (Villiers); Crête de Nion (no collector's name). Ivory Coast: Agboville, Yapo For., Yapo-Gare (I. Löbl); Abidjan, Banco Nat. Pk (I. Löbl); Tai Forest(V. M a h n e r t); Man (Mahnert & Perret); Man, Mt Tonkou (I. Löbl); Zaidon (I. Löbl); Sassandra, Monogaga, Monoho Pt (I. Löbl); Sangouiné (I. Löbl). Ghana: Bunso (R. Belshaw); Tafo (B. Bolton); Tafo (R. Belshaw); Poana (R. Belshaw); Mabang (R. Belshaw); Sui For. Reserve (R. Belshaw); Atewa For. Res. (H. Wright); Bobiri (R. Belshaw); Esunkawkaw (R. Belshaw); Kade (R. Belshaw); Akomodan (R. Belshaw); Sajymasi (R. Belshaw); Asiakwa (R. Belshaw); Asiakwa (H. Wright); Nkawkaw (R. Belshaw); Ofinso (R. Belshaw); Efiduase (R. Belshaw); Juaso (R. Belshaw); Tinte Bepo For. Res. (R. Belshaw); Mankrang (R. Belshaw); Jachie (R. Belshaw). Nigeria: Ibadan(A. Russel-Smith); Gambari (B. Bolton). Cameroun: Mbalmayo (N. Stork); Nkoemvon (D. Jackson); Prov. Sud, N’Kolo, Bondé For., Elogbatindi (B.L. Fisher); Prov. Sud, Res. Campo, Massif des Mamelles, Ebodjé (B.L. Fisher); Prov. Sud, P.N. Campo, Campo (B.L. Fisher); Res. de Campo (D.M. Olson); Prov. Sud, Res. de Faune de Campo (B.L. Fisher); Prov. Sud-Ouest, Bimbia For., Limbe (B.L. Fisher); Prov. Sud-Ouest, Korpu, Mundemba (B.L. Fisher). Gabon: La Makandé, For. des Abeilles (S. Lewis); Prov. Ogooue-Maritime, Res. Moukalaba (B.L. Fisher); Prov. Ogooue-Maritime, Res. Monts Doudou, Doussala (B.L. Fisher); Prov. Woleu-Ntem, Minvoul (B.L. Fisher); Prov. Estuaire, Pointe Ngombe, Ekwata (B.L. Fisher); Prov. Estuaire, F.C. Mondah, Libreville (B.L. Fisher); For. de la Mondah, Cap Esterias, n. Libreville (Bartolozzi & Taiti). Central African Republic: Dzanga-Sangha, Bayanga (B.L. Fisher); Dzanga-Ndoki, Mabéa Bai (B.L. Fisher); Dzanga-Ndoki, Lidjombo (B.L. Fisher). Congo: Res. de Tchimpounga, Pointe Noire, surr. Lac Foni (Bartolozzi & Bambi). Democratic Republic of Congo: Epulu (S.D. Torti). Angola: W. Gabela (P. H a m m o n d). Eritrea: Nefasit (Escherich). Sudan: Equatoria, Lotti Forest (N.A. Weber). Uganda: Kibale For. Res. (M.R. Orr); Kalinzu For., Bushenyi Distr. (S. Yamane); nr Mbarara (S. Yamane). Kenya: Tana R., Wema (Mahnert & Perret); Kisumu, Chemelil (V. Mahnert); Lamu, Lk Mukunguya (Mahnert & Perret); Embu, W. Ishiara (Mahnert & Perret); Western Prov., Kakamega For., Colobus (G. F i s c h e r); Colobus (M. Peters); Kakamega For., Buyanga (M. Peters); Kakamega For., Ikuywa (F. Hita Garcia); Kakamega Distr., Isecheno (R.R. Snelling); Isecheno For. Res., Kalunya Glade (R.R. Snelling); Malindi (Bartolozzi); Arabuko Sokoke For. Res., S. Malindi (Miss. Acc. Lincei). Tan zania: Mahale Mts N.P. (M. Kiyono); Morogoro Reg., Mkungwe For. Res. (Hawkes, Bhoke & Richard); Lindi Reg., Rondo For. Res. (Hawkes, Mlacha & Ninga); Mtwara Reg., Mkunya River proposed FR (Hawkes, Mlacha & Ninga). Zimbabwe: Bulawayo (G. Arnold). South Africa: Natal, Durban (H.W.B. Marley); Natal, Dukuduku Nat. Res. (D.J. Brothers); KwazuluNatal, Umtamvuna Nat. Res. (S. van Noort); E. Cape, Mkambati Game Res. (B.L. Fisher); Mpumalanga, Songimuelo Nat. Res., Komati Riv. (D. Ubick).