Austroplebeia Moure

Engel, Michael S., Herhold, Hollister W., Davis, Steven R., Wang, Bo & Thomas, Jennifer C., 2021, Stingless bees in Miocene amber of southeastern China (Hymenoptera: Apidae), Journal of Melittology 2021 (105), pp. 1-83 : 33-35

Genus Austroplebeia Moure

The genus Austroplebeia encompasses five species of rather distinctive Australian and Papuan stingless bees ( Moure, 1961; Michener, 1990, 2007; Dollin et al., 2015; Halcroft et al., 2016) ( Figs. 45–47 ). Within Australia, Austroplebeia occurs across the north and then along eastern Australia south to northern New South Wales. In addition, a single species is present in New Guinea, found throughout the Papuan (Bird’s Tail) and Huon Peninsulas in the east and then westward north of the Central Highlands to at least the eastern boundaries of West Papua ( Fig. 23 ). In New Guinea the genus is represented solely by Austroplebeia cincta (Mocsáry) , and this species should be sought in the Doberai (Bird’s Head) Peninsula, south of the Central Highlands, and perhaps also on the Tanimbar, Aru, and Kai Islands as these are biogeographically allied to Australia and east of Wallace’s Line. Although Tanimbar and Kai are west of the Lydekker Line and so may not harbor a New Guinean species like A. cincta , there are Papuan and Australian endemic species in those faunas, such as the kangaroo Thylogale brunii (Schreber) ( Macropodidae ) in the Kai and Aru Islands. The Aru Islands are situated on the Arafura Shelf and during episodes of glaciation have been contiguous with New Guinea and northern Australia ( Yokoyama et al., 2001), and harbor largely evergreen forests that are part of the Vogelkop-Aru Lowland Rainforest Ecosubregion ( Wikramanayake et al., 2002). Thus, populations of A. cincta would have had easy access to at least these small islands during periods of the recent past. Kai and Tanimbar are part of the Banda Sea Islands Moist Deciduous Forests Ecoregion ( Monk et al., 1997), all which would seemingly represent suitable habitat for A. cincta as long as some long-distance dispersal event allowed for the arrival of the bees. These islands have been poorly surveyed for Anthophila and this must be addressed to beter understand the regional biogeography and evolution of Papuasian bees.

The genus can be quickly distinguished from other Indomalayan-Australasian lineages of Meliponini by the presence of distinct yellow maculation on the head and mesosoma ( Figs. 45–47 ). In addition, the genus has the keirotrichiate zone of the retrolateral metatibial surface broad, with only a narrow, slightly depressed, superior glabrate zone, and the keirotrichia extend to the apical margin rather than separated by a broad apical glabrate zone ( Fig. 48 ). The fringe setae along the retromargin of the metatibia are simple, and the corbicula is comparatively shallow on the prolateral surface apically. The mesoscutellum is rounded but not thickened in profile, and somewhat projects over the metanotum medially. The basal area of the propodeum is about as long as or slightly longer than the mesoscutellum and slopes gently to a rounded angle with the vertical posterior surface.

Quite remarkably, a single distinctive species of Austroplebeia was recovered from Zhangpu, although in far lesser abundance than T. florilega , described above. The fossil agrees with the circumscription of Austroplebeia in virtually all details, with the exception of some differences in the head and wing venation. Based on these differences the species is placed into a new subgenus, but there are far more shared characters than differences. In order to emphasize these shared similarities and the interesting biogeographic connection, we have preferred such a classificatory arrangement to a more extreme and finely split system in which the fossil is placed in its own genus that, while exceptionally similar and related to Austroplebeia , would still obscure its linkage to those species of Australia and New Guinea. Regardless, the presence of a species from the Austroplebeia clade in southeastern China during the Middle Miocene greatly expands the historical geographic occurrence of the genus outside of the Sahul (= Meganesia or Austrolinea) and into mainland Asia.

In the keys to genera of Indomalayan and Papuasian Meliponini (Rasmussen et al., 2017; Engel et al., 2018), the fossil runs naturally to Austroplebeia . The following couplet allows for distinguishing the two subgenera now included therein and can be used in conjunction with the earlier keys.

Figures

Figure 23. Map depicting modern day distributions of Tetragonula Moure (green line) and Austroplebeia Moure (red line) in relation to the deposits at Zhangpu (red star). Map produced using Shorthouse (2010).

Figures 45–48. Photographs of workers of Austroplebeia (Austroplebeia) cincta (Mocsáry) from New Guinea. 45. Lateral habitus. 46. Dorsal habitus. 47. Facial view. 48. Retrolateral surface of metatibia and metabasitarsus.