Lasiotheus nanus ( Escherich, 1903 )

Mendes, Luis F., 2012, Description of the male of Lasiotheus Paclt, 1963, its implication in Atelurinae supra-generic taxonomy and keys for the genera (Insecta: Zygentoma), Zootaxa 3573, pp. 18-32 : 19-20

Lasiotheus nanus ( Escherich, 1903)

( Figs. 1 , A–D)

Material examined: Gabon: Province of Ogooué-Ivindo, lodge in the vicinity of the Parc National de La Lopé, 0 6.08.2009, sandy slope at the Offoué River left bank, 1 male (CZ-5749). Province of Moyen Ogooué, Lambarené, garden, 13.08.2009, ca. 30 m from the Ogooué River right bank, 1 female (CZ-5752). Province of Ngounié, Mouila, untreated garden not far from the Ngounié River right bank, 16.08.2009, 2 females (CZ-5755).

Male: Body length 2.4 mm, length and width of thorax 0.9 mm. Antennae and terminal filaments apically damaged though much shorter than body. The great majority of the morphological features agree well with those of females ( Mendes, 1986 and recent material collected in Lambarené and in Mouila), viz. body shape, head and body chaetotaxy (scales, type and distribution of macrochaetae and small setae), shape and proportions of mouthparts, shape of pretarsus and empodium morphology, number of abdominal stylets and number and shape of vesicles and pseudovesicles. However, the antennal pedicellus is modified, round, as long as wide, and with a clear fovea; like that of female, it lacks an apophysis ( Fig. 1 A); tergite X is similar to that of female in dorsal view, though somewhat deeper incised apically, but it shows three ventral, sub-equal, thin, cylindrical, sclerotized pegs on each side ( Fig. 1 B); parameres are short and very wide, with dense and strong distal glandular setae ( Fig. 1 C); the median posterior coxite VIII is entire, more or less straight, not protruded ( Fig. 1 C); and cerci are similar to those of female, but the dorsal basal divisions of the paracercus have a few long and thin, cylindrical, sclerotized pegs ( Fig. 1 D).

L. nanus is known to occur (probably due at least partly to human-introduced populations) in Guinea, Nigeria, Angola, South Africa (Kwazulu– Natal, Durban area), several African islands and archipelagos ( Cape Verde, St. Tomé and Príncipe, Reunion, St. Helena, Seychelles), as well as in Peru, Brazil, Hawaii, China, Sumatra, Melanesia ( Solomon Islands) and Polynesia ( Cook Islands). In most of its huge known range the species is almost always found with ants of the genus Pheidole (Myrmicinae) , which almost certainly is its primary host-genus; however, it also was reported once from an insectarium in Holland in a Tetramorium guyanensis nest (also Myrmicinae). The Gabon male, also associated with Pheidole sp., is new record for Gabon, from which only one Zygentoma was hitherto known: Hematelura doriae , reported from near Libreville by Silvestri (1918, sub Monachtinella ). The presence of males and females of L. nanus in Gabon suggests that Central West Africa may correspond to the species’ original range.

The set of morphological features observed in the Lasiotheus male reinforces its complete independence relative to the remaining genera of Atelurinae . Regarding the features already considered as diagnostic for both Lasiotheus and Pseudogastrotheus ( Paclt 1963, Mendes 2003), as well as the newly reported characters linked with sexual dimorphism of the terminal filaments, it is very likely they belong to distinct evolutionary lines. In Lasiotheus the sclerotized pegs are restricted to the dorsal basal paracercus (cerci without pegs) and in Pseudogastrotheus they are exclusive to the basal inner cerci (paracercus, devoid of specialized chaetotaxy).

Figures

FIGURE 1. Lasiotheus nanus (Escherich, 1903), male. A) Base of antenna. B) Tergite X, ventral. C) Right coxites and stylus VIII and IX, and right paramere. D) Base of paracercus, dorsal view. Scales: 0.1 mm.