Heterotrigona (Sahulotrigona) paradisaea Engel, 2017

Engel, Michael S. & Rasmussen, Claus, 2017, A new subgenus of Heterotrigona from New Guinea (Hymenoptera: Apidae), Journal of Melittology 2017 (73), pp. 1-16 : 8-10

Heterotrigona (Sahulotrigona) paradisaea Engel & Rasmussen, new species

ZooBank: urn:lsid:zoobank.org:act:29B861B9-A7A4-4BD2-99E0-D2AC9F1C1890

( Figs. 1–10 )

Trigona (Pacificotrigona) okazawai Tadauchi et al., 1998: 245 , nomen nudum.

DIAGNOSIS: The new species is distinguished from its closest relative, H. atricornis , by its darker coloration (cf. Figs. 1 and 11 ), more pronounced pubescence on the apical terga, and frequently larger number of distal hamuli on the hind wing. There are likely morphometric differences between the two species, but given the small sample sizes available we have not made an attempt to establish diagnostic differences which likely would require significant revision once series of workers become available.

DESCRIPTION: ⚲: Total body length approximately 5.8 mm (5.3–5.8 mm), forewing length (including tegula) 6.0 mm (5.6–6.3 mm). Head wider than long, width 2.08 mm (2.01–2.16 mm), length 1.56 mm (1.56–1.88 mm); compound eye length 1.28 mm (1.22–1.40) mm; upper interorbital distance 1.30 mm (1.25–1.40 mm), lower interorbital distance 1.25 mm (1.17–1.30 mm). Scape length 0.78 mm (0.76–0.80 mm), about as long as torulocellar distance, torulocellar distance 0.78 mm (0.76–0.86 mm); flagellomeres about as long as wide except apical flagellomere longer than wide. Clypeus broader than long, approximately 1.8–1.9 times as wide as long, length 0.52 mm (0.47–0.52 mm), width 0.94 mm (0.89–1.00 mm). Malar area short, length approximately subequal to flagellar diameter or 0.6 times basal mandibular width ( Fig. 2 ). Mandible with two, small preapical teeth ( Fig. 3 ); P 1 with narrow incision separating apical edentate margin; incision separating P 1 and P 2 slightly less than orthogonal, with acutely rounded angular vertex (not to be confused with the vertex of the head; the angular vertex, i.e., the geometric vertex or point where two edges of an angle meet; in this case is the point where the lower edge of P 2 meets the upper edge of P 1 and together form the angle between these two teeth, with the inner point of the incision between them representing the vertex for the angle, which in this case is acutely rounded: refer to figure 3).

Integument generally black to dark brown ( Fig. 1 ), except labiomaxillary complex brown and reddish brown areas on inner surface of metatibia and metasomal terga I–IV; wing veins dark brown, nebulous traces dark brown to brown, membrane infuscate more so apically in radial cell and in and around marginal cell ( Fig. 7 ).

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

Pubescence generally white or dark fuscous to black ( Figs. 1, 2 , 4–6 ). Face with numerous minute, silvery white setae ( Fig. 2 ), those on clypeus largely appressed to subappressed and simple except subapically to apically plumose, those on face more plumose and subappressed, but not obscuring integument; setae of upper frons gradually becoming dark fuscous to nearly black and mostly simple, gradually intermingled with longer, erect, simple, black setae; such erect, black setae predominate on vertex, particularly posterior to ocelli; gena with scattered erect to suberect, black setae; scape with minute to short (always much less than scape diameter), dark fuscous, simple setae. Mesosomal dorsum with dark fuscous to black setae ( Fig. 4 ), except fine, minute setae of metanotum silvery white; mesoscutum and mesoscutellum with abundant, erect, minute setae with some branches, such setae not obscuring integument and intermingled with more scattered, longer, erect, simple, black setae, such longer setae more abundant on mesoscutellum than mesoscutum; basal area of propodeum glabrous except for sparse, apicolateral patches of fine, white setae, such setae with a few branches. Pleura with abundant, minute, white, branched setae, intermingled anteriorly with some erect, simple, fuscous setae; shorter setae of propodeal lateral surfaces becoming somewhat fuscous posteriorly. Setae of legs dark fuscous to black. Metasoma with discs largely glabrous, with minute, suberect, simple, fuscous setae laterally, such setae becoming progressively more present, albeit still sparse, over discs of third through fifth terga; such setae forming appressed vibrissae in narrow apical zones of second through fifth terga; longer, erect to suberect, simple, black setae scattered laterally on fourth tergum and progressively more abundant across fifth and sixth tergum; fifth tergum with appressed to subappressed, minute, simple setae of apical zone extending more extensively posteriorly in apical portion of disc; sixth tergum with numerous, erect to suberect, short, branched, dark fuscous setae. Sterna with long, erect, simple, fuscous setae on discs.

♀: Latet.

♂: Latet.

HOLOTYPE: ⚲, Neu Guinea [ Papua New Guinea], Strasse Wau-Mt. Kaindi , 7 km S Wau [southern Morobe Province, Momase Region, Bulolo District], 12.9.1972 [12 September 1972], Hohmann ( SEMC).

PARATYPES: Papua New Guinea: 1⚲, Neu Guinea [Papua New Guinea], Strasse Wau-Mt. Kaindi , 7 km S Wau [southern Morobe Province, Momase Region, Bulolo District], 12.9.1972 [12 September 1972], Hohmann ( SEMC) ; 4⚲⚲, Gang Creek Camp, Mt. Rawlinson , 4500 ft, viii-3-1964 [3 August 1964], 7 th Archbold Exped. to New Guinea, Huon Peninsula, Morobe District, H.M. Van Deusen collector ( AMNH) ; 2⚲⚲, New Guinea, Papua, Mt. Dayman , Maneau Range , north slope, 1550 m, camp #5, July 5–8, 1953, G.M. Tate, 4 th Archbold Expedition ( AMNH) ; 5⚲⚲, Wau, Kaisinik, Morobe, xii 22 1973 [22 December 1973] // Papua New Guinea , xii 1973 – I 1974 [December 1973 – January 1974], T. Okazawa ( RMNH) .

COMMENTS: It is interesting to note that Hohmann (2003) does not mention this locality in his summary of his studies on the biology of New Guinean stingless bees. This is perhaps because while he collected at the locality, he did not manage to sample nests or amass communication data from species while there.

A series of specimens differ in their overall darker appearance. In particular, the minute white to silvery setae of the face, mesosomal dorsum, metanotum, and propodeum are dark fuscous to black. Longer, erect, simple setae of the mesosomal dorsum are black without any pale or light setae, unlike the type series of H. paradisaea . Sakagami considered these as a subspecies of what we have called H. paradisaea , but as we could not identify structural differences and have no biological or biogeographical information about the populations, we exclude them from the type series, listing them as H. (S.) cf. paradisaea . The label data are included below in a separate section for reference.

ETYMOLOGY: The specific epithet is based on the generic name Paradisaea Linnaeus ( Aves: Passeriformes : Paradisaeidae ), the genus of the Emperor bird-of-paradise ( Paradisaea guilielmi Cabanis) which is the national emblem of Papua New Guinea. The name is meant to honor the unique biota cultivated by the indigenous peoples of New Guinea.

Figures

Figures 1–3. Worker of Heterotrigona (Sahulotrigona) paradisaea, new subgenus and species, from eastern Papua New Guinea. 1. Lateral habitus. 2. Facial view. 3. Outer view of mandible (P = preapical tooth).

Figures 4–6. Worker of Heterotrigona (Sahulotrigona) paradisaea, new subgenus and species, from eastern Papua New Guinea. 4. Dorsal view of head and mesosoma. 5. Detail of propodeum in oblique dorso-posterior view. 6. Lateral view of mesosoma, detailing mesoscutellar profile.

Figures 7–10. Worker of Heterotrigona (Sahulotrigona) paradisaea, new subgenus and species, from eastern Papua New Guinea. 7. Forewing. 8. Outer view of metatibia and metatarsus. 9. Inner view of metatibia and metatarsus with posterior glabrate (yellow), apical glabrate (blue), keirotrichiate (green), and sericeous (pink) areas colored (arrows indicate width of posterior glabrate and length of apical glabrate zones). 10. Unmodified view of inner surface of metatibia and metatarsus.

Figures 11–14. Workers of Heterotrigona (Sahulotrigona) atricornis (Smith), from eastern Papua New Guinea (non-type specimens). 11. Lateral habitus of dark morph. 12. Facial view of dark morph. 13. Lateral habitus of yellowish orange morph. 14. Facial view of yellowish orange morph.