Ceratina (Ceratinidia) compacta, a Small Carpenter Bee in Thailand: An Apparent Recent Addition to the Fauna (Hymenoptera: Apidae)

This paper records the existence in Thailand of Ceratina compacta Smith, 1879 (Hymenoptera: Apidae), a species known previously only from the Philippines. Thai records of Ceratina species span several previous decades. The subgenus Ceratinidia Cockerell and Porter, 1899, to which C. compacta belongs, is one of the eight subgenera of Ceratina found in the Oriental Region (Terzo, 2000). This group of ca. 26 species (Michener, 2000) ranges from India to Papua New Guinea (west to east) and from the Maritime Province of Siberia to Indonesia (north to south) (Hirashima, 1971). The species are usually considered solitary, but some species express primitive social behavior (Michener, 1990; Maeta, 1993; Maeta and Sakagami, 1995; Sakagami and Maeta, 1995). Ceratina species visit and probably pollinate many flowers. They use their stems and other dead stems as nest sites. It is probably for this reason that several species of the genus are adventives in various areas, e.g., species in subgenera Calloceratina (from Mexico to Texas, Michener, 2000), Neoceratina (from Old World to Hawaii, Snelling, 2003), and Euceratina (from Europe to California and from Southwestern US to Hawaii, Michener, 2000; Snelling, 2003). Ceratinidia species are medium-sized to small bees with shiny black bodies maculated with striking yellow patterns. As shown by van der Vecht (1952), C. compacta has been recorded only from the Philippine Islands, where it is a common and well known species (Smith, 1879; Ashmead, 1904; Cockerell, 1915, 1916, 1918, 1920a, b, 1925a, b; Hedicke, 1927; van der Vecht, 1952). Ceratina compacta morphologically resembles its presumed sister species, C. lieftincki van der Vecht, 1952, known from Indochina, the Malay Peninsula, Java, and Palawan. In C. lieftincki, the antennal scape is black and the mesopleura less densely punctured than in C. compacta (see Table 2 for other comparable characters). The two species are distinguishable from other Ceratinidia species in Thailand by various characters, see revision of the subgenus (Warrit, in prep.). Among 1345 museum specimens of Ceratinidia examined, no specimen of C. compacta was from regions other than Thailand and the Philippines, excepting one specimen from Northern Sulawesi (another new distributional record outside of the Philippines). Eighty-eight specimens of C. compacta from the Philippines Islands and 12 specimens from Thailand were examined. The first specimen of C. compacta from Thailand is a male labeled "Thailand: Kanchanaburi: 110 air km W of Bangkok 25-27 April 1988, W. J. Pulawski collector" (California Academy of Sciences collection). Subsequent collecting localities for C. compacta in Thailand are shown in Figure 1 and Table 1. Natural habitats for C. compacta collected by the author are mostly either in agricultural areas or recovered forest where the primary vegetation was destroyed. Many specimens of other Ceratinidia species were collected in Thailand before 1988 (I have seen 38 such specimens), yet not a single C. compacta was found before that date. Species of Ceratinidia found in historical collections from Thailand are Ceratina (Ceratinidia) accusator Cockerell, C. bryanti Cockerell, C. cognata Smith, C. collusor Cockerell, C. lieftincki van der Vecht; and C. nigrolateralis Cockerell. Populations of C. compacta vary in the Philippines (van der Vecht, 1952; Warrit, pers. obs.), but a definitive conclusion as to the island from which the Thai population originated cannot be confirmed. However, because Ceratina nest in plant stems, importation of local floral materials containing nests of C. compacta from the Philippines may have caused the introduction of the species into Thailand. The possibility that C. compacta in Thailand represents a new species cannot be completely eliminated until substantial numbers of specimens of both sexes from various localities in the Philippines and Thailand are available for morphological and molecular