Descriptions of two new species of the genus Colocasiomyia (Diptera, Drosophilidae) breeding on Rhaphidophora host plants in Yunnan, China

Abstract

The genus Colocasiomyia de Meijere (Diptera, Drosophilidae) is known to include 30 described and nearly 60 undescribed species classified into six species groups. Among these, the C. gigantea group of seven known species (two Southeast Asian and five Chinese) proved to be peculiar for its specificity on monsteroid (subfamily Monsteroideae, family Araceae) host plants. In this paper, two new species, C. todai Jiao & Gao, sp. nov. and C. liae Jiao & Gao, sp. nov., are described as members of the C. gigantea group with specimens collected from inflorescences of the monsteroid host species Rhaphidophora peepla (Roxb.) Schott and R. crassicaulis Engl. & Krause, respectively, in Yunnan, China. The two new species are delimitated, in comparison with all known species, based on not only morphological but also DNA barcode (partial sequence of the mitochondrial COI, i.e., cytochrome c oxydase subunit I, gene) data. A revised key to all the nine species of the C. gigantea species group is provided.

Evolution of the Colocasiomyia gigantea Species Group (Diptera: Drosophilidae): Phylogeny, Biogeography and Shift of Host Use

“…In a recent study [ 4 ], a cladistic analysis of 70 morphological characters of 24 species covering all six groups in Colocasiomyia was conducted, where the gigantea group (represented by C. gigantea , C. scindapsae and C. rhaphidophorae ) was found to have the synapomorphy “foreleg tarsomere II elongated below”, and was placed as a sister to the cristata group. This synapomorphy in all the subsequently described species of the group, together with the appearance of egg filaments observed in the earliest member of the gigantea group, were confirmed in all the subsequently described species of the group, with the evolutionary significance of egg filaments readily recognized [ 4 , 5 , 8 , 9 ].…”

“…We used RASP version 4 [ 19 ] to reconstruct the biogeographic history of the gigantea group through S-DIVA (statistical dispersal-vicariance analysis) on the ML tree constructed above. For this, we compiled data on the geographical ranges of the ten species in the gigantea group and the outgroup species from the literature [ 2 , 3 , 4 , 5 , 6 , 8 , 9 ], with the total range divided into five areas that referred to the Kangar-Pattani Line [ 20 ], Wallace’s Line [ 21 ] and Lydekker’s Line [ 21 ] ( Figure 1 ): A—the northeastern Oriental region (referred to as the “NE Oriental region” below for convenience) with southern China, including Hainan and Taiwan + Ryukyu Islands + Sino-Himalaya + Indochina Peninsula; B—Sundaland; C—the Philippines; D—Wallacea; E—the Australian region (referred to as “Australian” below). Then, a S-DIVA analysis was conducted with four allowed areas in ancestral distribution.…”

“…For this, we created a standard categorial matrix for the 15 representative Colocasiomyia species and two characters: the host use and body size. For the host use, we discriminated four states ( Table 2 ) by referring to the literature [ 3 , 5 , 8 , 9 ] or our unpublished data: 0 (the subfamily Aroideae), 1 (the genus Rhaphidophora ), 2 (the genus Scindapsus ) and 3 (the genus Epipremnum ).…”

“…For the body size, we used the thorax length (ThL) (defined as the distance from the anterior notal margin to the apex of the scutellum [ 23 ]), with data compiled from the original descriptions of the type specimens in the taxonomic literature or newly collected ( Table A2 ), For this character, we discriminated two states (small vs. large): 0 (small: ThL ≤ 1.0 mm) and 1 (large: ThL ≥ 1.2 mm). For Colocasiomyia liae , only two specimen types were employed based on their original descriptions [ 8 ]. In our analysis, we treated the state of the body size of this species as ambiguous (indicated with “?” by default).…”

“…All these species were taxonomically assigned into six species groups, with each adapted to a specific host plant lineage: the crassipes group adapted to the family Magnoliaceae (the genus Michelia Linn. ), the zeylanica group adapted to the family Arecaceae (the genus Pinanga Blume) and the remaining four groups adapted to the family Araceae: the toshiokai , baechlii and cristata groups adapted to the subfamily Aroideae, and the gigantea group adapted to the subfamily Monsteroideae (the genera Rhaphidophora Hassk, Epipremnum Schott and Scindapsus Schott, all belonging to the Rhaphidophora clade [ 7 ]) [ 3 , 4 , 5 , 8 , 9 ] ( Table A1 ).…”