The southernmost member of the Simulium venustum species group (Diptera: Simuliidae) in the Old World: a new species from the Rif Mountains of Morocco Author Belqat, Boutaïna LESCB URL / CNRST N ° 18, FS, Abdelmalek Essaadi University, Tetouan, Morocco Author Adler, Peter H. Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA text Zootaxa 2024 2024-04-30 5446 2 247 256 http://dx.doi.org/10.11646/zootaxa.5446.2.6 journal article 295386 10.11646/zootaxa.5446.2.6 03e4548e-b280-4c63-8aa6-1dbd2493c3be 1175-5326 11101670 82B6D308-1D97-48A0-9318-5E24047476B6 Simulium chaouikaidi Belqat & Adler , n. sp. Simulium ‘indet.’ Belqat, Adler & Dakki, 2001 Simulium ‘sp.’ Belqat, 2002 Simulium ‘sp.’ Belqat & Dakki, 2004 Simulium ‘sp.’ Belqat, Dakki & Alami, 2005 Simulium ‘sp.’ Belqat, Adler & Crosskey, 2011 Simulium ‘indet. ’ Belqat, Adler, Cherairia & Boudghane-Bendiouis, 2018 Simulium ‘indet.’ Adler, 2022 Simulium ‘indet.’ Adler, 2023 Chromosomal characterization. The three chromosomes in the haploid complement expressed tight pairing of homologues and had well-defined, darkly staining centromere bands within expanded centromere regions, mildly so in chromosomes II and III ( Fig. 1 ) and markedly so in chromosome I. Five of the six chromosome arms had the standard banding sequence for the subgenus Simulium , whereas the sixth arm (IIS) was fixed for inversion IIS-C ( Table 2 ; Fig. 1A, B ). TABLE 2. Frequency of chromosomal inversions in Simulium chaouikaidi n. sp. from Morocco, relative to the Simulium subgeneric banding sequence.

Site	1	2	3	4a	4b	4c
Females: Males	1:0	1:0	0:1	4:3	1:1	14:4
IIS-C	1.00	1.00	1.00	1.00	1.00	1.00
IIIL-11	-	-	-	-	-	0.06

Note: A dash (-) indicates the inversion was not found. The sex chromosomes were cytologically undifferentiated; the X and Y were microscopically identical. Autosomal polymorphisms were scarce; only one, a small inversion (IIIL-11), was heterozygous ( Fig. 1C ) in 2 larvae ( Table 2 ). Diagnosis. Chromosomally, S. chaouikaidi n. sp. is distinguished from all known species of Simuliidae , except S. paramorsitans , by a combination of the fixed IIS-C sequence, standard sequence for IIIL, and microscopically undifferentiated sex chromosomes. The combination of an elongated, narrow ventral plate (2.6 times as long as wide) and finely haired prominence at the base of the gonostylus distinguishes the male from all other species of Simuliidae . The six slender filaments in the same vertical plane and the tightly woven, slipper-shaped cocoon separate the pupa from all other North African Simuliidae . The negative head-spot pattern, arrow-head shaped postgenal cleft, and six-filamented gill histoblast distinguish the mature larva from all other known species of Simuliidae in the Palearctic Region. The female remains unknown.