Ceratina (Ceratina) sirikitae Sless, Tucker & Rehan 2026, sp. nov.

Ceratina (Ceratina) sirikitae Sless, Tucker & Rehan sp. nov. Fig. 6 Type material. Holotype: Thailand • 1 ♀; “ Chiang Mai Prov., Alt Queen Sirkit [sic] Botanic Gardens ”; 18°52'50.7"N, 98°51'42.3"E; 28 Mar. – 3 Apr. 2009; [malaise trap]; Kaewjanta & Sawkord leg.; QSBG-2009-64 M; RCYU “ rsTha 03 ”. Paratypes: Thailand • 2 ♀; “ Chiang Mai Prov., Alt Queen Sirkit [sic] Botanic Gardens ”; 18°52'57.5"N, 98°51'39.5"E; 841 m; 20–27 Mar. 2009; [malaise trap]; Kaewjanta & Sawkord leg.; QSGB-2009-50 O, QSGB-2009-50 D; RCYU “ rs 2 Tha 01 ”, “ rs 2 Tha 02 ” • 1 ♀; “ Trang, Nayong, Khaochong ”; 7°33.038'N, 99°47.369'E; 75 m; 10-24 Feb. 2005; RCYU “ rs 2 Th 05 ”. Diagnosis. Distinguished from other members of Ceratina s. s. (as well as Neoceratina) by its red abdomen, foretibia with more extensive maculation, and 2 nd submarginal cell nearly closed anteriorly with rs vein absent or extremely narrow. Description. Female (Fig. 6). ♀ (holotype and paratypes): body length 5–5.5 mm; forewing 3.6 mm; head 1.4 mm wide × 1.4 mm long. Color: Head and mesosoma shiny black (Fig. 6 A, B); mandibles ferruginous medially; labrum black; clypeus with longitudinal pale yellow maculation reaching upper margin (Fig. 6 D); paraocular area and gena without maculations; pronotal lobes with pale maculation in posterior 1 / 2; tegulae ferruginous and translucent (Fig. 6 C); fore tibia with basal pale spot as well as second, disconnected maculation along ~ 1 / 2 of its length (resembling an inverted exclamation mark); mid tibia with tiny, barely noticeable basal spot; hind tibia with maculation covering ~ 1 / 3 of its length; tarsi ferruginous; abdomen largely bright red except T 1 and S 1 dark brown basally, T 2 with two dark brown patches at lateral sides, T 4 with interrupted dark brown band, T 5 – T 6 dark brown; rims of terga somewhat translucent. Head: Labrum and clypeus sparsely punctured (Fig. 6 D); supraclypeus mostly smooth with few punctures along lateral edges, changing to abruptly punctured between antennal sockets; upper frons with two rows of punctures extending above antennal sockets and running between lateral and median ocelli; inner margin of compound eye with a sparse line of fine punctures; dense punctures posterior to ocelli and along preoccipital margin, extending laterally into upper genal area which is moderately punctured; vestiture sparse, absent from most of face; rear margin of vertex and genae with a fringe of medium-length erect white hairs; some similar hairs present between antennal bases, around ocelli, and on mandibles and labrum; a few much shorter hairs on clypeus, along inner eye margins, and on scape. Mesosoma: Scutum moderately punctate in anterior third (1–3 diameters apart), becoming largely impunctate medially except for dense punctures along lateral margins and in posterior sixth of segment (Fig. 6 C); scutellum densely punctured throughout (~ 1 diameter); metanotum densely but shallowly punctured; propodeum with dorsal area imbricate to shagreened; propleuron densely punctured; mesopleuron moderately punctured, with spaces of 1–3 puncture widths, hypoepimeral area mostly impunctate (Fig. 6 E); metapleuron densely punctured with minute pits femora weakly expanded medially and slightly flattened below; tibiae slightly narrower than femora, with curved apical spine on fore and mid tibiae, basitibial plate indistinct vestiture sparse dorsally; scutum hairless except around edges; scutellum and metanotum with white hairs over much of surface; propleuron with evenly spaced semi-erect medium-length hairs; mesopleuron with long but sparse white hairs, becoming denser on ventral surface; lateral faces of propodeum with very short but moderately dense white hairs; fore and mid legs with a few long white to light brown hairs on femur and tibia, scopal hairs on hind leg longer but not much denser; all three basitarsi with denser and slightly darker vestiture in comparison to more basal segments of legs. Metasoma: Graduli present on T 2–5 and S 2–5 (Fig. 6 B); T 1 smooth; T 2 pregradular area weakly strigulate and impunctate, postgradular area moderately punctured (1–3 diameters apart); T 3 pregradular area smooth, postgradular area densely punctured (~ 1 diameter), though impunctate just before densely punctate apical depression; T 4–5 postgradular area densely punctured including most of apical depression; T 6 densely punctured; S 1 smooth; S 2–3 postgradular area sparsely punctate (2–5 diameters); S 4 – S 5 postgradular area more densely punctate (1–3 diameters); S 6 punctures dense (~ 1 diameter); vestiture sparse on terga, mostly consisting of short light hairs within apical depressions, though T 4 – T 6 with denser hairs; S 2 – S 5 with sparse rows of long, erect, white hairs apically, more uniformly distributed on S 6. Etymology. Named in reference to the type locality, Queen Sirikit Botanic Garden (Chiang Mai Province, Thailand). Distribution. Thailand. Specimens collected from tropical and subtropical moist / dry broadleaf forest biomes. Remarks. Male unknown. We have compared specimens of C. sirikitae with other Indomalayan / Eastern Palearctic members of Ceratina s. s. recovered as the sister group to Neoceratina in the phylogeny of Sless et al. (2024), namely C. belliata, C. iwatai, C. sauteri, and C. yamanei. As mentioned in the diagnosis, C. sirikitae is easily distinguished from these four species based on the abdominal coloration, though it also has a larger maculation covering roughly 1 / 2 of the fore tibia, compared to a tiny basal spot or entirely black tibia in the others. As discussed below, this group of species is not closely related to other members of Ceratina s. s., and in future should either be united with Neoceratina or designated as another new subgenus. To our knowledge, the red abdomen of C. sirikitae is unique among members of both Ceratina s. s. and Neoceratina, though of course is present in some species of Scuticeratina as described above as well as a few species of Xanthoceratina, Calloceratina, and Ceratinula (Michener 2007). However, C. sirikitae can easily be distinguished from Scuticeratina and Xanthoceratina by the absence of paraocular maculations, and presence of punctures (though quite sparse) between antennal bases and ocelli. This species is unlikely to be confused with Calloceratina, which is Neotropical in distribution and typically brightly metallic. Ceratina sirikitae is morphologically very similar to some Ceratinula despite their significant phylogenetic distance (Fig. 2, Suppl. material 2), including the apically narrowed 2 nd submarginal cell (though this feature is also present in various other small-bodied Ceratina; Michener 2007), and may run to this subgenus in the key. However, Ceratinula is a Neotropical subgenus sharing no range overlap with the Indomalayan C. sirikitae, and is included in the Eastern Hemisphere key only due to the presence of C. arizonensis in Hawaii where it has been introduced (Hirashima 1971; Michener 2007).