Simulium

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 : 15-16

Simulium nr. asakoae 3

(Figs. 6D, 7D, 9D, 11D)

The following morphological description is based on two pupae and three larvae from site 38.

Diagnosis: The larva can be distinguished from those of other cytoforms by the combination of greenish transverse bands on abdominal segments I and IV and a postgenal cleft that is twice as long as the postgenal bridge. The pupa can be distinguished from those of other cytoforms by the combination of a crenulated outer margin on each terminal hook and a 60-degree angle formed by the stalks of the ventral pair and dorsal triplet.

This cytoform differs morphologically from S. asakoae as follows:

FIGURE 7. Idiograms 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 . Fixed inversions are underlined and shown on the left side; floating inversions are in parentheses and shown on the right side. IS, short arm of chromosome I; IL, long arm of chromosome I; IIS, short arm of chromosome II; IIL, long arm of chromosome II; IIIS, short arm of chromosome III; IIIL, long arm of chromosome III. BL = blister, BR = ring of Balbiani, C = centromere, db = double bubble, jg = jagged group, m1 = basal marker of IIIL, m2 = end marker of IIIL, NO = nucleolar organizer, PB = parabalbiani. a Exact breakpoints of the inversion have not been determined.

Female and male. Unknown. Pupa. Gill filaments ( Fig. 11 D) (3) + (1 + 2) + 2 from dorsal to ventral, with angle formed by stalk of ventral pair of filaments and that of dorsal triplet less than 90 degrees when viewed laterally; terminal hooks each with crenulated outer margin. Larva. Abdominal segments I and IV each with greenish transverse band and segments V–VIII each with reddish-brown transverse band dorsally.

Chromosomes. We analyzed the chromosomes of 15 larvae from site 38. The chromosomes stained faintly and the centromere regions were not expanded. This cytoform was fixed for IIL-9 (Fig. 5A), which was shared with S. curtatum n. sp. and S. nr. asakoae 2, and for a set of inversions in IIIL, designated IIIL-complex 5 (Fig. 6D). In addition, seven floating inversions were discovered: IS-4 (Fig. 2A), IL-2, IL-3 (Fig. 2B), IIL- 10 (Fig. 5A), IIIL-2, IIIL-3, and IIIL-4 (Fig. 6D).

Bionomics. The pupae and larvae of this cytoform were attached to fallen leaves and trailing plants in a single stream 1.5 m wide, with high conductivity (166.7 µs/cm) at an altitude of 600 m in northern Thailand ( Table 3 ).

Figures

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.