Simulium nr. asakoae 4

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

The morphological description below is based on two larvae and two pupae from site 52.

Diagnosis: The larva is characterized by a deep postgenal cleft and the absence of color markings dorsally on the abdomen. The pupa cannot be distinguished from that of other cytoforms.

This cytoform differs morphologically from S. asakoae as follows:

Female and male. Unknown. Pupa. Gill filaments (Fig. 11 E) (3) + (3) or (1 + 2) + 2 from dorsal to ventral, with stalk of ventral pair of filaments as long as stalk of middle triplet; terminal hooks each with crenulated outer margin; cocoon densely woven. Larva. Postgenal cleft (Fig. 9 E) deep, ca. 5.4 x as long as postgenal bridge, with apex almost reaching hypostomal groove.

Chromosomes. The chromosomes of three larvae from site 52 were analyzed. The chromosomes were fixed for inversions IS-8 (Fig. 2A) and IIS-11 (Fig. 4A), and a complex set in IIIL (IIIL-complex 9, Fig. 6E). The centromere regions were not expanded. Only one floating inversion, IIL-12 (Fig. 5A), was observed.

Bionomics. This cytoform was collected from fallen leaves in a small (0.3 m wide), shaded stream at an altitude of 330 m in northeastern Thailand (Table 3). It was associated with small populations of S. angulistylum, S. burtoni, and S. siamense.