Trachusa aff. vietnamensis Flaminio & Quaranta, 2021

Nalinrachatakan, Pakorn, Ascher, John S., Kasparek, Max, Traiyasut, Prapun, Thanoosing, Chawatat & Warrit, Natapot, 2023, A review of the anthidiine bees (Apoidea, Megachilidae) in Thailand, ZooKeys 1186, pp. 235-284 : 235

Trachusa aff. vietnamensis Flaminio & Quaranta, 2021

Figs 16 , 17

Trachusa vietnamensis Flaminio & Quaranta in Flaminio et al. 2021: 307-310, fig. 1 (♀). Holotype from Quang Nam, Vietnam (CREA: Consiglio per la ricerca in agricoltura e l’analisi dell’economia agrarian (Bologna, Italy), examined).

Material examined.

(5♀). Thailand: Phitsanulok, Nakhon Thai District , 27 May 2014, N. Warrit et al. (CUNHM: BSRU-AA-4471-4475) .

Distribution.

Thailand (Phitsanulok) and Vietnam (Quang Nam).

Diagnosis.

The species is very close to, or maybe identical to Trachusa vietnamensis . Only the female is known: body large, robust, and black. Bands with yellowish, orangish, or light-brown coloration on the vertex, preoccipital area, anterolateral of scutum, and scutellum, while mesosoma covered in orangish pubescence. The Thai specimens are distinguished from the Vietnamese material by a unique elongate metasoma making it more chalicodomiform, and more limited maculation on the metasoma (fully striped on T1 and T2 of T. vietnamensis , small pale marks on the side of T1 and T2 and minute or absent on T3 and T4 for Thai specimens). The species is also close to T. ovata , from which it differs by the combination of five mandibular teeth, clypeus black with ill-defined shiny median longitudinal line, conspicuous rounded light-brown scutellum which seems darker basally, and head with orangish to light-brown maculations running continuously from the vertex to genal area.

Description.

Female: Body length 13.4, 13.3, 13.2, 13.0, 13.3 mm, head width 4.3, 4.3, 4.2, 4.3, 4.1 mm, intertegular distance 3.6, 3.8, 3.8, 3.7, 3.5 mm, respectively. Wingspan 25.0, 25.6, 25.0, 24.7, 24.9 mm.

Head largely black, with light-brown band on vertex running continuously to genal area, lighter on occipital ridge, but not abutting margins of eyes and ocelli. Clypeus (see Fig. 16C ) black, slightly convex but shallow depression apically with ill-defined shiny median longitudinal line; middle and apical area with smaller and denser punctures, apical margin slightly crenulate thus looking somewhat emarginate at middle. Surfaces apically covered with sparse short yellow hair that is dense and long. Supraclypeal area black, slightly convex, with shiny median longitudinal line. Mandible broad with apex ~ 1.5 × wider than base. Mandibles somewhat dull, black with light-brownish mark on basal area, inner surfaces with hairs. Four mandibular teeth, apical tooth larger than inner. Labrum black, with yellow bristles on its apex. Maxillary palpus three-segmented, black but dark brown on rounded basal segment. Subantennal suture slightly arcuate outwards. Antenna generally brown, scape brown but darker on front, pedicel dark brown to black, flagellum lighter in color on medial front, F1 and F2 brighter than rest. Ocellooccipital distance not more than 1.5 × interocellar distance. Head covered with fulvous hair, denser and longer on frons, paraocular area, and lower part of genal area.

Mesosoma black, covered with fulvous hair except on pronotum with exposed shiny black median area with coarse punctures. Pronotal lobe strongly carinated, light brown. Mesepisternum black. Omaulus carinated, extending to ventral part of thorax. Scutum laterally carinate, punctures uniform, dense, with light-brown color on anterolateral band, not abutting together in middle. Axilla rounded laterally, entirely light brown. Tegula fulvous with dark patch lining medio-posterior. Scutellum broad, apically round with median emargination, light brown, darker on median triangular basal area.

Wing subhyaline, fuscate, forewing darker at apical margin and marginal cell. Pterostigma brown. Veins dark brown to black; 2nd recurrent vein abutted to 2nd submarginal crossvein distally.

Legs covered with short fulvous hairs. Coxae, trochanters, and basal parts of femora dark reddish brown to black; legs otherwise light brown except dark brown on inner surfaces of basitarsus and tarsi, slightly subtle on outer surfaces of hind basitarsus and hind tarsal segments. Apical tarsal segments with apical dark spot. Claw with inner tooth, light brown, apically black. Arolium present, dark brown to black.

Metasoma black. Discs of all terga swollen, with fine dense punctures. Terga covered with short black hairs, lighter to fulvous hairs on T1-T3 lateral surfaces, longer fulvous hairs covering frontal carina of T1. T1 and T2 with small pale lateral patches (Figs 16A, B, D , 17C ) with part of obscured thin line extending to median. In some paratypes, these patches can be more or less expressed, tending to form an almost continuous thin but obscure band on disc, and also obscurely found on T3 and T4 in one specimen (BSRU-AA-4471). Scopa pale yellow on S2 and S3, gradually darker on S4, and becoming black on S5 and S6. S1-S6 reddish brown to black, darker apically. T6 with barely visible small median emargination.

Remarks.

Trachusa species have been reported from upper and lower Indochina but with limited materials ( Soh et al. 2016; Kasparek 2017, 2019a; Flaminio et al. 2021). It is plausible that the lack of previous records in Thailand, Burma, and Cambodia may be due to limited collecting, in addition to the general rareness of Trachusa bees. This is the first record of Trachusa in Thailand: all specimens are neither complete nor in perfect condition.

Since the species is very close to T. vietnamensis from Vietnam, here we propose that the Thai specimens belong to the same species. The differences in tergal bands on the metasoma may be considered as variation; however, the Thai specimens exhibit a more elongate metasoma. To confirm that both species are indeed the same, DNA barcoding would be useful since the barcode of T. vietnamensis was provided by Flaminio et al. (2021).

Subgeneric placement of Trachusa vietnamensis is still uncertain. Kasparek (2017, 2019a) assigned three species groups in Paraanthidium with their characteristics: interrupta group (female with bright yellow maculations on black, wasp-like), Hemidiellum longicornis group (Indomalayan species with female having dull yellow maculation except on the mesosoma), Trachusa ovata group (female completely without maculation), and the remaining Trachusa xylocopiformis (Mavromoustakis, 1954), for which only the male is known Fukien, China, is large and black except for yellow on lower part of the face.

Trachusa vietnamensis seems to not be congruent with any of these groups, but is closely related to the Trachusa ovata group by its face, especially in its clypeal shape, and the reduced maculation on the metasoma. Also, the superficially color pattern and almost parallel-sided body form are not congruent with the robust-megachiliform that occurs in all described females of Paraanthidium ; from this, it more resembles the subgenus Paraanthidium Orthanthidium from mainland China and Taiwan for which two fairly different species are known: Trachusa formosana (Friese, 1917) and T. cornopes Wu, 2004. Orthanthidium was designated by Mavromoustakis (1953) prominently for its parallel-sided axilla, truncated scutellum, and small spine on the tibial apex. As Orthanthidium is still problematic in its status ( Kasparek 2017), future work is still needed.

The astonishing record of another Trachusa species that is completely different from the aforementioned T. aff. vietnamensis has been retrieved from the citizen science database platform iNaturalist ( iNaturalist 2023) from Thailand: Chiang Mai, Mueang District, Suthep Subdistrict, Doi Suthep-Pui (18°49'00.5"N, 98°55'26.8"E), observed repeatedly by “jackychiangmai” on 16 Apr, 30 Apr, and 27 May 2022 (observation id: 111730798, 114167310, 119204705 respectively).

Since the identification is restricted to the available photographs, we cannot identify the bee definitively. These observations show multiple Trachusa bees (25+) grouping on a semi-limestone concrete surface (Fig. 18 ) along with other bees, including Ceratina (Ceratinidia) spp., Chelostoma aureocinctum (Bingham, 1897), possibly Hylaeus sp., and a Halictinae bee (possibly Pachyhalictus or Lasioglossum ). This Trachusa species exhibits a large robust body with a round scutellum, while the yellow band on T4-T6 and the yellowish brown patch apically on the leg can also be noticed. Most bees that can be speculated for their sex are usually female based on their pollen-loaded metasomal scopa. Based on the available information, we classify these Trachusa bees to the subgenus Trachusa Paraanthidium , primarily within Hemidiellum longicornis group that contains four described species at present: T. longicornis (Friese, 1902), T. maai (Mavromoustakis, 1953), T. muiri (Mavromoustakis, 1937), and T. rufobalteata (Cameron, 1902) (see discussion above and Kasparek 2017). Collections and information are needed in order to confirm its identity.

Keys to the species of Anthidiine bees in Thailand

Two keys are provided below, one for females and one for males. The keys are modified from Baker (1995), Michener (2007), Engel (2009), Niu et al. (2019), and Flaminio et al. (2021). They both exclude morphospecies known only from citizen science records.

Figures

Figure 16. Female Trachusa aff. vietnamensis BSRU-AA- 4473 (A), 4744 (B-E) A lateral habitus B dorsal habitus C face D lateral of metasoma E antennae. Scale bars: 2 mm (A, B, D); 1 mm (C, E).

Figure 17. Female Trachusa aff. vietnamensis (BSRU-AA- 4475) A ventral habitus of mouthparts (with removed mandible) B mid tibia C all specimens in dorsal view, showing variation (BSRU-AA- 4471 - 4475, respectively from left to right). Scale bar: 2 mm (C); 0.5 mm (A, B).

Figure 18. Groups of Trachusa (Paraanthidium) sp. primarily identified as Hemidiellum longicornis group sensu Kasparek (2017), gather with other bee species. Photograph: Jacky Cudon.