Recent Divergence of Neolitsea-associated Pseudasphondylia Gall Midges (Diptera: Cecidomyiidae) with Description of a New Species from Taiwan

Abstract

Taiwanese Pseudasphondylia species inducing spherical leaf galls on six Neolitsea hosts, viz, N. acuminatissima, N. daibuensis, N. konishii, N. parvigemma, N. sericea and N. variabillima, was regarded as a species allied to Japanese P. neolitseae Yukawa due to similarity of gall structure and host. The Taiwanese species is morphologically different from P. neolitseae in adult palpus segmental number, shapes of pupal antennal horn, pupal prothoracic spiracle, and larval sternal spatula, resulting in its description as a new species to science, Pseudasphondylia hooki sp. n. The species delimitation (Assemble Species by Automatic Partitioning method) supported that P. hooki sp. n. is distinct from P. neolitseae. The sistership of P. hooki sp. n. and P. neolitseae was also supported in the Maximum likelihood tree based on the 1^st codon of COI region. The speciation event of them is assumed to be geographical isolation because the divergence corresponded to the separation of Taiwan and Japan in the Pleistocene. The patterns of ecological features (host species) on the phylogeny revealed that galling on N. sericea is primitive of Neolitsea-associated Pseudasphondylia lineage. Accordingly, the divergence pathway from north to south in Taiwan is suggested by the distributions of primitive (N. sericea) and most derived hosts (N. daibuensis).

Keywords: Asphondyliina; Biogeography; East Asia; Phylogeny; Speciation.

Fig. 1.

Leaf galls of Pseudasphondylia hooki sp. n. on Neolitseae species (A) N. acuminatissima, (B) N. daibuensis, (C) N. konishii, (D) N. sericea (E) N. parvigemma, and (F) N. variabillima.

Fig. 2.

Pseudasphondylia hooki sp. n. (A) Male head (ventral view) (B) Male antenna (8–12 segment). (C) Female antenna (8–12 fragellomeres). (D) Male 5th tarsomere. (E) Female 5th tarsomere. (F) Male wing. (G) Female wing. (H) Male genitalia. (I) Female abdomen. (J) Pupal abdomen. Scale bars: A–C = 0.03 mm; D–E = 0.2 mm; F–G = 1 mm; H = 0.2 mm; I–J = 0.5 mm.

Fig. 3.

Phylogenetic tree based on the 1^st codon positions of COI (T93+G) and morphological differences of Neolitsea-associated Pseudasphondylia gall midge, P. hooki sp. n. (left) and P. neolitseae (right). The bootstraps (%) of Maximum-Likelihood inferences were shown beside nodes (1^st codon/ 1^st +2^nd codons). Score less than 60 were hidden.

Fig. 4.

Assemble Species by Automatic Partitioning (ASAP) analyses of Neolitsea-associated Pseudasphondylia gall midges based on mitochondrial partial COI region. Colors represent unique partitions. Gray and Yellow dots of branches refer to P value incalculable and greater than 0.1, respectively.

Fig. 5.

Saturation plots of transition (blue line) and transversion (green line) rates against F84 distance.