Megachile (Carinula) stulta Bingham, 1897 Figs 32, 33

Megachile stulta Bingham, 1897: 476; Female syntype (NHMUK, examined) Sikkim, India.

Diagnosis.

Female can be recognized by its medium to small body size (7.83-10.39 mm); rough clypeus with median carina, apical margin crenulate (Fig. 33b); mandibles four teeth with two stout apical teeth at apex and two small teeth basally; labrum rectangular (Fig. 33c); metasoma covered with ferruginous hairs (Fig. 33e); scopa ferruginous except white basal area (Fig. 33f).

Literature records.

India. Karnataka, Sikkim (Ascher et al. 2016; Ascher and Pickering 2020); Indonesia. Sumatra (Bingham 1897; Ascher and Pickering 2020); Malaysia. Kuala Lumpur, Selangor (Ascher et al. 2016; Ascher and Pickering 2020); Myanmar. Tenasserim (Bingham 1897); Singapore. (Ascher et al. 2016). In addition, six females of this species was among numerous megachilids photographed together at Hin Tung, Mueang District, Nakhon Nayok Province (iNaturalist) (credit: scottyastro 2015; shuanda 2019).

Material examined.

Female syntype. India. "Type; B.M. TYPE. 17.a.2161b; Megachile stulta Bingh, female, Type.; SIKKIM, Rungjit Valley, 1000 ft., 4.94, BINGHAM COLL., Col. C. T. Bingham 96-30; NHMUK 013380269"; Thailand. Kamphaeng Phet Province: 1♀, Khlong Lan, Khlong Lan waterfall, 08-IV-2014, coll. C. Wimolsuthikul & S. Wongvilas (leg. NC and NW); 36♀, Pang Sila Thong district, Mae Wong National Park, Kang Pha Khoi Nang, 07-VIII-2015, coll. N. Warrit et al. (leg. NC and NW).

Notes on Callomegachile from Thailand

Two of the most common species of Megachile (Callomegachile) sensu lato found in Thailand are M. (Callomegachile) disjuncta and M. (Callomegachile) umbripennis, and these are also the most common species of this group in Singapore (Ascher et al. 2016). Megachile (Callomegachile) disjuncta is usually collected from Crotalaria juncea L. across most of Thailand.

This is the first study to emphasize the importance of labral shape (Fig. 34a-o) for the identification in female Callomegachile species. In Thailand, M. (Callomegachile) disjuncta is the only species that has two prominent lateral teeth on distal edge of labrum (Fig. 34c), whereas in M. (Callomegachile) fulvipennis, M. (Callomegachile) impressa and M. (Callomegachile) faceta the lateral teeth are less prominent (Fig. 34e, f, d). Megachile (Callomegachile) umbripennis in Thailand has smooth and slightly concave distal edge of labrum (Fig. 34j). Megachile (Callomegachile) parornata has convex distal edge of labrum and M. (Callomegachile) chiangmaiensis sp. nov. has a distinct distal edge: medially convex with large lateral teeth (Fig. 34b). Further investigation into the applicability of the labral distal edge as diagnostic character in other Callomegachile species should be carried out.