Heterotrigona (Sahulotrigona) taraxis, Engel, 2019

Engel, Michael S., 2019, Notes on Papuasian and Malesian stingless bees, with the descriptions of new taxa (Hymenoptera: Apidae), Journal of Melittology 2019 (88), pp. 1-25 : 7-9

Heterotrigona (Sahulotrigona) taraxis Engel, new species

ZooBank: urn:lsid:zoobank.org:act:14F27D4D-D8B9-4C39-AC58-D3B6B520DA40

( Figs. 8–9 )

“ Trigona atricornis ” (Smith) , auctorum.

DIAGNOSIS: This species is most similar to H. paradisaea , both of which lack the fringe of mesoscutal setae present in H. tricholoma (vide supra). Heterotrigona taraxis can be distinguished from H. paradisaea by the lighter integumental coloration which is dark chestnut brown (rather than black to dark brown in the later species) ( Figs. 8, 9 ), and the less abundant setation of the fifth metasomal tergum.

DESCRIPTION: ⚲: Total body length approximately 5.1 mm, forewing length (including tegula) 5.5 mm. Head wider than long, width 1.96 mm, length 1.53 mm; compound eye length 1.23 mm; upper interorbital distance 1.26 mm, lower interorbital distance 1.16 mm. Scape length 0.70 mm, slightly shorter than torulocellar distance, torulocellar distance 0.73 mm; flagellomeres about as long as wide except apical flagellomere longer than wide. Clypeus broader than long, approximately 1.7× as wide as long, length 0.47 mm, width 0.80 mm. Malar area short, length approximately subequal to flagellar diameter. Intertegular distance 1.26 mm. Hind wing with 6 distal hamuli.

Integument generally dark chestnut brown ( Figs. 8, 9 ), narrow apical marginal zones of terga lighter and semitranslucent; wing veins brown, lighter posteriorly, nebulous traces brown, membrane hyaline and clear albeit faintly around apex of marginal cell.

Integument mostly smooth and shining, with exceedingly minute punctures at bases of setae but otherwise impunctate. Metasomal terga smooth and largely impunctate except sparse punctures at bases of setae, minutely punctured in narrow apical zones owing to bases of minute, appressed, apically directed setae; sterna faintly imbricate, with weak nodulae at bases of setae on discs, narrow apical zones impunctate and glabrous.

Pubescence generally white to black and coppery. Face with numerous minute, silvery white setae, those on clypeus largely appressed to subappressed and simple, those on face more plumose and subappressed, but not obscuring integument; setae of upper frons gradually becoming finer, more erect, dark fuscous to nearly black and mostly simple, gradually intermingled with longer, erect, simple, black setae; such erect, black setae predominate on vertex; gena with fine, erect to appressed, minute, simple, white to coppery setae; postgena with erect, elongate, fine, simple setae; scape with minute to short (shorter than diameter of scape), fuscous, simple setae. Mesosomal dorsum with erect, dark fuscous to black setae ( Fig. 8 ) and fine, minute, plumose, coppery setae, longer erect setae sparser on mesoscutum, particularly on centrally, more abundant and elongate on mesoscutellum; metanotum with abundant, fine, short, simple, white setae; basal area of propodeum glabrous except for diffuse, apicolateral patches of fine, white, largely simple setae. Pleura with abundant, minute, white, branched setae, intermingled anteriorly and ventrally with short to elongate, erect, simple, white setae; such plumose setae of metepisternum and propodeal lateral surface nearly obscuring integument. Setae of legs coppery to black. Metasoma with discs largely glabrous, with minute, suberect, simple, coppery to fuscous setae laterally, such setae becoming progressively more present, albeit still sparse, over discs of third through fifth terga; such setae forming appressed, diffuse vibrissae in narrow apical zones of second through fifth terga; longer, erect to suberect, simple, fuscous to black setae scatered laterally on fourth tergum, scatered over disc of fifth tergum, and abundant across sixth tergum; fifth tergum with appressed to subappressed, minute, simple setae of apical zone extending more extensively posteriorly in disc; sixth tergum with numerous, erect to suberect, short, branched, coppery setae. Sterna with long, erect, simple, coppery setae on discs, such setae paler on more basal sterna.

♀: Latet.

♂: Latet.

HOLOTYPE: ⚲, New Guinea (NE) [ Papua New Guinea, Northeast], Boana Mission [on the slope of Mt. Bangeta, a.k.a. Mt. Sarawaket], Huon Pen. [Huon Peninsula, Morobe Province], 900 m, ix-4–5-1959 [4–5 September 1959] // E.J. Ford, Jr., collector ( SEMC).

ETYMOLOGY: The specific epithet is taken from the Greek, taraxis (τᾰρᾰΧῆς), meaning, “confusion”, and is a reference to the historical confusion regarding the identity of this species.

COMMENTS: This species has been long confused as “ Trigona atricornis Smith ”, as most authors have relied on historical material identified as this species in collections (e.g., Michener & Sakagami, 1990; Engel & Rasmussen, 2017). A recent examination of the holotype of T. atricornis in the Oxford University Museum of Natural History reveals that Smith’s (1865) species in actuality belongs to the genus Papuatrigona Michen- er & Sakagami wherein it is a senior synonym of T. genalis Friese (vide infra). It appears as though Friese (1898, 1909, 1915) was the first to misidentify this species, and it seems that all subsequent authors have followed his concept based on material he identified.

Figures

Figures 8–9. Worker holotype of Heterotrigona (Sahulotrigona) taraxis, new species, from Papua New Guinea. 8. Lateral habitus. 9. Facial view.