Stegana (Stegana) rotunda, 2010

Li, Tong, Cao, Huazhi, Gao, Jianjun & Chen, Hongwei, 2010, A revision of the subgenus Stegana (s. s.) (Diptera, Drosophilidae) from mainland China, Zoological Journal of the Linnean Society 158 (4), pp. 726-739 : 735

STEGANA (STEGANA) ROTUNDA CAO & CHEN SP. NOV. ( FIGS 36–40 )

Specimens examined: Holotype male, China: Guangxi, Guilin, Maoershan , 630 m, 21.ix.2006, ex tree trunks, JJ Jiang ( SCAU, no. 120291).

Etymology: From the Latin word rotundus, referring to the aedeagus being slightly rounded apically.

Diagnosis: Katepisternum almost dark brown; paramere with 15–17 strong setae ( Figs 39, 40 ); surstylus without prensiseta ( Fig. 37 ).

Description: Frons, face, and clypeus yellow. First flagellomere yellow on basal third, black on distal two-thirds. Gena brown. Mesonotum yellow, sublaterally with two brown stripes on each side. Scutellum brown. Legs yellowish white, fore leg brown on knee and tibia; mid and hind leg black on femora and basal three-quarters of tibiae. Fore femur with four setae on distal part of ventral surface. Abdomen with all tergites and sternites black. Male terminalia: hypandrium somewhat sclerotized anteromedially ( Fig. 38 ). Gonopods with one curved process posteromedially and two smaller triangular processes submedially ( Figs 39, 40 ). Aedeagus with several tentacle-like setae apically and spine-like processes ventrally, lacking pubescence ( Figs 39, 40 ).

Measurements: BL = 2.46 mm in holotype; ThL = 1.22 mm; WL = 1.88 mm; WW = 0.95 mm. Indices: arb = 7/5, avd = 0.73, adf = 1.67, flw = 2.22, FW/HW = 0.33, ch/o = 0.08, prorb = 1.00, rcorb = 0.80, vb = 0.29, dcl = 0.56, presctl = 0.70, sctl = 1.84, sterno = (damaged), orbito = 2.31, dcp = 0.24, sctlp = 1.50, C = 1.91, 4c = 1.25, 4v = 1.86, 5x = 1.18, ac = 9.26, M = 0.50, C3F = 0.63.

Distribution: China (Guangxi).

RESULTS OF MOLECULAR PHYLOGENETIC ANALYSIS

Data analysis

The alignment of the ND2 sequence was 1029 nucleotide sites in length, coding 342 amino acid residues, containing 183 parsimony-informative characters, with consecutive gaps at sites 267–269 in some sequences. The average base frequencies of the ND2 sequences (including outgroups) calculated in MEGA were 36.6, 45.0, 7.8, and 10.6% for A, T, G, and C, respectively, showing strong bias towards A and T. It was revealed by the Chi-square test that the base composition is not homogeneous among taxa (P = 0.8208) at the third codon position, but homogeneous at the first and second codon positions (P = 1.000 and 1.000, respectively), or even the average data (P = 0.9988). The test of substitution saturation in DAMBE showed that the observed Iss index is 0.1707, significantly lower than the Iss.c

Figures

Figures 36–40. Stegana (Stegana) rotunda Cao & Chen sp. nov., male: 36, epandrium, surstylus, and cercus; 37, surstylus; 38, hypandrium and gonopods; 39, paramere, aedeagus, and aedeagal apodeme; 40, hypandrium, gonopods, paramere, aedeagus, and aedeagal apodeme. For orientation, see Figures 1–7. Scale bars = 0.1 mm.