M. (Anodonteutricharaea)

Praz, Christophe J., 2017, Subgeneric classification and biology of the leafcutter and dauber bees (genus Megachile Latreille) of the western Palearctic (Hymenoptera, Apoidea, Megachilidae), Journal of Hymenoptera Research 55, pp. 1-54 : 6-7

Subgenus Anodonteutricharaea

Diagnosis and description.

This subgenus is widely distributed in the Old World ( Trunz et al. 2016). Of the criteria given here, not all will apply to Anodonteutricharaea outside the Palearctic; characters that appear constant in this subgenus throughout its range are the elongate basal seta on the claws in the female (Fig. 7 ), which is the most salient diagnostic trait to identify the females of Anodonteutricharaea; and the absence of an inferior projection on the mandible and the characteristic shape of the gonostylus in the male (Fig. 50 ). Females: Palearctic females of Anodonteutricharaea agree with Eutricharaea in their small to medium size, mostly white or yellowish white scopa (although it is orange in Megachile albohirta). The sterna do not have continuous, apical fasciae beneath the scopa. In contrast to Eutricharaea, the mandible is similar to that of the subgenus Megachile s. str. (Figs 30-31 ), with a partial cutting edge in the second interspace and no visible cutting edge in the third interspace in the Palearctic species; often in Anodonteutricharaea, the cutting edges are entirely recessed and invisible in front view (Fig. 31 ). Also as in Megachile s. str., the mandible is 5-toothed, or if 4-toothed, the upper tooth is truncate and weakly divided into two teeth, thus approaching the 5-toothed condition (Fig. 30 ). In some species, there is a straight, carinate ridge in the middle of the interacetabular interspace; this ridge is placed above the outer ridge (see Gonzalez and Engel 2012: Fig. 5 ) and extends form the mandibular base to the middle of interspace 1 (Figs 30-31 ). In most other group 1 subgenera, this ridge is less visible, less carinate or regularly curved. Males: Males of Anodonteutricharaea can be diagnosed by the absence of projection along the inferior margin of the mandible, unlike most other group 1 subgenera; the mandible is either 3- or 4-toothed. The gonostylus is distinct and diagnostic (Fig. 50 ): it is broadened apically, with numerous hairs on the external surface. In the Palearctic, the few known species are superficially similar to Eutricharaea in the light body vestiture, the presense of a front coxal spine (spine short in M. villipes), the T6 with disc covered by dense, white tomentum and multidentate preapical carina, and the small, unmodified T7 (except in M. albohirta, where T7 is produced to a short median tooth). In most Palearctic species, the front tarsi are slightly enlarged, yellowish-white or yellowish-brown and have a black macula ventrally on tarsal segments 2 (most species) or 1 and 2 ( M. albohirta). Palearctic Anodonteutricharaea are readily distinguished from Eutricharaea in the hyaline apical margin of S4 (Fig. 12 ).

Species composition.

The Palearctic species of Anodonteutricharaea form a rather homogenous group; how this group relates to the eight species groups recognized by Pasteels (1965) for the African fauna remains to be investigated. The following western Palearctic species belong to this subgenus: Megachile albohirta, M. inornata, M. thevestensis, and M. troodica. M. mandibularis and M. villipes are probably restricted to Central Asia and records of the latter from the western Palearctic ( Schulthess 1924, Zanden 1989, Özbek and Zanden 1994) likely refer to other species. I have seen at least three additional, undescribed species in the western Palearctic.

Biology.

Very little is known on the biology of this subgenus. Ferton (1920) described nests of Megachile thevestensis. The cells were placed individually or in groups of two in existing cavities between rocks or in burrows in the soil; it was unclear whether the female had dug the burrow or used a preexisting burrow. All cells investigated consisted of an external, rigid layer of leaf fragments (not circularly cut as in most other group 1 subgenera) and a layer of petals inside. I have captured M. villipes on Alhagi ( Fabaceae) in Uzbekistan, while M. inornata and a closely related, undescribed species appear oligolectic on Lamiaceae. M. troodica also appears to have a distinct or exclusive preference for Lamiaceae ( Mavromoustakis 1953), and in M. thevestensis and another, undescribed species from Morocco, the hairs on the median parts of the clypeus are short and simple, suggesting pollen collection from nototribic flowers such as Lamiaceae (see comments under the subgenus Pseudomegachile).

Figures

Figures 4 - 7. Claw of hind leg of females; the white lines show the basal seta; the seta is considered elongate in 4, 6 and 7 and modified to a thick process in 5. 4 Megachile (Pseudomegachile) ericetorum 5 M. (Eutricharaea) deceptoria 6 M. (Eurymella) patellimana 7 M. (Anodonteutricharaea) thevestensis.

Figures 50 - 53. Apex of male metasoma, dorsal view. 50 Megachile (Anodonteutricharaea) sp. aff. inornata 51 M. (Pseudomegachile) ericetorum 52 M. (Pseudomegachile) saussurei 53 M. (Pseudomegachile) foersteri.

Figures 30 - 37. Female clypeus and mandibles, front view. 30 Megachile (Anodonteutricharaea) albohirta 31 M. (Anodonteutricharaea) thevestensis 32 M. (Megachile) versicolor 33 M. (Megachile) lapponica 34 M. (Megachile) bombycina 35 M. (Xanthosarus) lagopoda 36 M. (Xanthosarus) nigriventris 37 M. (Xanthosarus) willughbiella.

Figures 10 - 15. Male metasoma, ventral view. 10 Megachile (Eutricharaea) giraudi, metasoma with four exposed sterna, S 4 without hyaline rim, T 7 small, unmodified 11 M. (Creightonella) amabilis, metasoma with six exposed sterna, S 6 with rounded, weakly sclerotized projection 12 M. (Anodonteutricharaea) sp. aff. inornata, metasoma with four exposed sterna, S 4 with apical, hyaline rim (note that S 5 - S 8 are visible in this specimen because the metasoma has been stretched) 13 M. (Megachile) ligniseca, condition as in Fig. 12 14 M. (Eurymella) patellimana, condition as in Fig. 12 15 M. (Chalicodoma) montenegrensis, S 6 partly exposed, with rounded, weakly sclerotized projection.