Monomorium hanneli species group

based on Bolton, 1987

Species

Diagnosis

Worker Monomorphic. Mandibles unsculptured, with 4 teeth which decrease in size from apex to base. Palp formula 2 ,2 (Monomorium jacksoni, Monomorium hanneli, Monomorium invidium). Median portion of clypeus with a pair of sharply defined posteriorly convergent raised carinae , which terminate at the anterior margin in a pair of short teeth. Frontal lobes close together, the median strip of clypeus which runs between them narrow, narrower to only fractionally wider than either of the frontal lobes. Eyes small, the maximum diameter 0.13-0.18 x HW; the eyes always with more than 5 ommatidia in total but less than 25, situated in front of the midlength of the sides of the head. Antennae with 12 segments, terminating in a large 3-segmented club. Head moderately broad and scapes relatively short, CI 81-90, SI 75-86. Propodeum usually very finely transversely sculptured , sometimes smooth, bluntly angular to bluntly bidentate where the dorsum meets the declivity. Petiolar peduncle short in profile, the node high and the spiracle behind the level of the anterior face of the node. Cephalic dorsum unsculptured except for h air-pits; lateral portions of clypeus, area immediately behind lateral portions of clypeus and area around antennal fossae without striolate or fine costulate sculpture . Fine standing hairs present on all dorsal surfaces of head and body. (Workers examined: all species of the group.)

Female Only very slightly larger than the conspecific worker. As worker but with proportionately much larger eyes, ocelli present, and alitrunk with a full complement of flight sclerites. HW distinctly greater than the maximum width of the mesoscutum, the latter as broad as long or slightly broader than long. In dorsal view the pronotum forming a part of the dorsal alitrunk, appearing as a broad transverse collar in front of the mesoscutum and being much wider laterally than mesally. Parapsidal grooves conspicuous to vestigial. Axillae in dorsal view wedge-like and with a gap between their inner apices; the length of the gap about equal to the length of one of the axillary sclerites. Propodeum bluntly angular to low bidentate at junction of dorsum and declivity. (Females examined: jacksoni, invidium.)

Notes

The five species of this distinctive and purely Afrotropical group are all very closely related and have no obviously related forms outside the region. With their narrow median clypeus, closely approximated frontal lobes and small eyes they appear at first glance to be close to the fossulatum-group (=Syllophopsis), but in workers of that group the petiolar peduncle is long and the node low, the eyes are usually only of a single ommatidium and the clypeus lacks teeth anteromedially. In the females the pronotum does not form part of the dorsal alitrunk in the fossulatum-group and the axillae of the latter are much closer together. It thus appears that the characters apparently shared by the workers are the result of convergence rather than indicators of genuine relationship.

All species of the hanneli-group form part of the leaf litter and topsoil fauna, nesting in rotten twigs in the litter layer or in tree stumps. Of the three West African species one, invidium, is very widespread and ranges from Ivory Coast to Cameroun in the forest zone. The other two, Monomorium guineense and jacksoni, are only known from the forests of Guinea and Cameroun respectively. The females of invidium and jacksoni mentioned above were the reproductives of established colonies; alate females remain unknown, as do all males of this group. The two Kenyan species, hanneli and Monomorium valtinum, are only known from the workers and from relatively few series.

Heterick's Malagasy Monomorium revision (Heterick 2006) also discussed this species group as one of the group's members (Monomorium hanneli) occurs on Madagascar.

Additional Resources

References