Simulium trangense, Jitklang, Sanae, Kuvangkadilok, Chaliow, Baimai, Visut, Takaoka, Hiroyuki & Adler, Peter H., 2008

Jitklang, Sanae, Kuvangkadilok, Chaliow, Baimai, Visut, Takaoka, Hiroyuki & Adler, Peter H., 2008, Cytogenetics and morphotaxonomy of the Simulium (Gomphostilbia) ceylonicum species group (Diptera: Simuliidae) in Thailand, Zootaxa 1917, pp. 1-28 : 19-20

Simulium trangense n. sp.

(Figs. 4B, 5B, 6H, 7G, 9G, 11G)

Simulium sp. nr. sheilae, Phasuk et al., 2005: 52 –57 (male, larva, chromosomes)

Simulium sp. nr. sheilae, Phasuk, 2006: 97 –103, 171–175, 181 (female, male, pupa, larva, chromosomes) [ Simulium sheilae: Phasuk et al., 2005 , not Takaoka and Davies: 52–57 (larva, chromosomes) (misident.)] [ Simulium sheilae: Phasuk, 2006 , not Takaoka and Davies: 92–96, 171, 174, 181 (female, male, pupa, larva, chromo-

somes) (misident.)]

Diagnosis: The larva is characterized by the combination of a deep postgenal cleft and yellowish abdomen with reddish-brown markings and branched setae dorsally. The pupa can be distinguished from that of other cytoforms by the scalloped outer margin on each terminal hook and an angle of more than 90 degrees between the stalks of the ventral pair and dorsal triplet of gill filaments.

This species differs morphologically from S. asakoae as follows:

Female. Sensory vesicle ca. 0.6 x as long as 3rd segment; mid trochanter dark yellow; tuft of hair at base of costa and on stem vein dark. Male. Upper eye of 9 or 10 vertical columns and 11 horizontal rows of large facets; scutum covered entirely with pale recumbent pile; subcosta bare. Pupa. Gill filaments ( Fig. 11 G) (1 + 2) + (1 + 2) + 2; angle formed by stalk of ventral pair and dorsal triplet more than 90 degrees when viewed laterally; ventralmost filaments ca. 1.7 x thicker than other filaments; terminal hooks each with crenulated outer margin. Larva. Postgenal cleft ( Fig. 9 G) deep, ca. 34.0 x as long as postgenal bridge, almost reaching hypostomal groove; abdominal segments with distinct reddish-brown bands; abdominal segments V–VIII bearing dark setae with 2–4 branches (rarely unbranched).

Chromosomes. We analyzed the chromosomes of 76 larvae from 9 populations (sites 23, 31, 39–44, and 50). This species was found with S. sheilae at three sites (sites 40, 42, and 44). The chromosomes stained well and the centromere regions were condensed in all chromosomes. The banding sequence was characterized by more than eight fixed inversions: one in IS (IS-3, Fig. 2A), four with ill-defined breakpoints in IIS (IIS-1, IIS- 2, IIS-3, IIS-4; Fig. 4B), two in IIL (IIL-2. 3 and IIL-5) (Fig. 5B), and a complex set of inversions in IIIL (IIILcomplex 1, Fig. 6H). Polymorphisms included inversions IS-7 (approximate breakpoints: sections 5–10), IIL- 4, IIL-6 (Fig. 5), and IIIL-5 (Fig. 6H). Inversion IIL-6 at site 31 was in Hardy-Weinberg equilibrium (χ 2 = 0.34, P> 0.05).

Remarks. The chromosomal banding pattern of this species conforms to that of S. nr. sheilae of Phasuk (2006), supporting synonymy.

Type specimens. Holotype: Male, with associated pupal exuviae and cocoon (in ethanol vial). THAI- LAND, Prachuap Khiri Khan Province, Huai Yang National Park, 11º37'N 99º36'E, 14.XII.2006, C. Kuvangkadilok, K. Meeyen, S. Jitklang, and U. Tangkawanit. Paratypes: 2 females, 1 male, 3 pupae, 5 mature and 72 immature larvae (transferred from Carnoy’s fixative to 95% ethanol), same data as holotype.

Bionomics. The larvae and pupae of this species were attached to fallen leaves and trailing grasses in warm (24.8 ºC), sandy or muddy streams, ranging in width from 0.3 to 6.5 m, at altitudes of 50–600 m, mostly in southern Thailand ( Table 3 ).

Etymology. The species name refers to Trang Province, where the species first was collected (from Ton Khlan waterfall).

Figures

FIGURE 9. Postgenal clefts of larvae of 10 cytoforms of the Simulium ceylonicum species group in Thailand. (A) S. asakoae, (B) S. curtatum n. sp., (C) S. nr. asakoae 2, (D) S. nr. asakoae 3, (E) S. nr. asakoae 4, (F) S. sheilae, (G) S. trangense n. sp., (H) S. doisaketense n. sp., (I) S. nr. sheilae 3, and (J) S. inthanonense. Scale bar = 0.1 mm.

FIGURE 11. Gill filaments of 10 cytoforms of the Simulium ceylonicum species group in Thailand. (A) S. asakoae, (B) S. curtatum n. sp., (C) S. nr. asakoae 2, (D) S. nr. asakoae 3, (E) S. nr. asakoae 4, (F) S. sheilae, (G) S. trangense n. sp., (H) S. doisaketense n. sp., (I) S. nr. sheilae 3, and (J) S. inthanonense. Scale bar = 0.1 mm.