Simulium

Adler, Peter H., Belqat, Boutaïna, González, Josefina Garrido, Pérez, Alexandre Justo & Seitz, Gunther, 2016, Chromosomal relationships of Simulium armoricanum and its undescribed sister species in the Simulium vernum species group (Diptera: Simuliidae), Zootaxa 4137 (2), pp. 211-222 : 219-221

Simulium ‘IL-8’

We analyzed the chromosome preparations of 4 larvae, all females, from Sites 3 and 4 ( Table 1).

Chromosomal complement. In our small sample, the following inversions were found in the homozygous condition: IL-2, IL-8, IIIP-1, and IIIL-1cy,ca. The last-mentioned inversion was associated with a homozygous, thin, strongly staining band (tb) at the junction of 86B and 88A ( Fig. 6 B). A subterminal heteroband (Hb45B) in IIS ( Fig. 6 A) was homozygous in all 4 larvae. A chromocenter, ectopic pairing, and B chromosomes were absent.

Sex chromosomes. Without males, no statement can be made about the sex chromosomes.

Autosomal polymorphisms. A subterminal heteroband (Hb74A) in IIIS ( Fig 6 B) was heterozygous in two larvae. This heteroband was distinct from the taxonomically widespread Hb74C2 of Hunter (1987).

Taxonomic status. No other chromosomally analyzed species in the S. vernum group has a banding sequence like that of our 4 larvae. In addition to European species that have been formally analyzed (summarized by Adler & Crosskey 2015), we have unpublished information for S. brevidens (Rubtsov) and S. quasidecolletum Crosskey , each of which is chromosomally unique and lacks inversion IL-8. We do not have chromosomal data for S. bertrandi Grenier & Dorier , S. codreanui (Sherban) , S. oligotuberculatum (Knoz) , or some of the putative Italian endemics. One of our 4 larvae, however, was mature, and its uncurled gill histoblast did not have an elongated base or a swollen dorsal trunk, eliminating S. codreanui and S. oligotuberculatum . The postgenal cleft was rounded or slightly angular anteriorly, suggesting that the species is not S. bertrandi , which has a more angular cleft (similar to that of S. argyreatum Meigen ). No pupae in the collections at Sites 3 and 4 had the elongated microtubercles with secondary granules characteristic of S. bertrandi ( Grenier & Dorier 1959) . We, therefore, suggest that these larvae represent a new, formally undescribed species, here designated Simulium ‘IL-8’. We refrain from formally describing a new species until additional life stages are collected.

Bionomics. Larvae were collected in two streams, both with open canopies. One stream (Site 3) was less than 0.5 m wide with a sandy and stony substrate, whereas the other (Site 4) was twice as wide with a sandy substrate and some macrophytes harboring the preimaginal stages.

Larvae were collected with those of S. aureum Fries sensu stricto, S. armoricanum , S. cryophilum complex, S. vernum sensu stricto, S. ornatum group and S. variegatum Meigen group.

Figures

FIGURE 6. Diagnostic features of Simulium ‘ IL- 8 ’. C = centromere. A. IIS arm (Site 3), showing homozygous subterminal heteroband (Hb 45 B). RB = ring of Balbiani, ‘ 3 ’ = 3 sharp marker. B. Chromosome III fixed for IIIP- 1 and IIIL- 1 cy, ca; a heterozygous subterminal heteroband (Hb 74 A) and a homozygous thin band (tb) are each indicated by an arrow. Bl = blister, bm = basal marker.