Simulium (Hemicnetha) falculatum Enderlein

Hernández, L. M. & Shelley, A. J., 2005, New specific synonymies and taxonomic notes on Neotropical blackflies (Diptera: Simuliidae), Zootaxa 853, pp. 1-46 : 3-4

Simulium (Hemicnetha) falculatum Enderlein

(Figs 1, 2, 33, 34, 36, 50, 64, 78)

Friesia falculata Enderlein, 1929: 327 –328. HOLOTYPE Ψ, MEXICO: Bora del Monte; [Without date.], (Purpus S.V.) (NMHU). [ Coscarón (1987: 36) regarded as possibly synonymous with Simulium (Hemicnetha) paynei Vargas, but Adler et al. (2004: 373) accepted as good species.] [Examined.]

Simulium coffeae Vargas, 1945b: 4 . Unnecessary replacement name for F. f a l c u l a t a [See Adler et al., 2004.]

Simulium falculatum was described by Enderlein (1929) as F. falculata from a single female collected in Bora del Monte, Mexico by S.V. Purpus. Later, Vargas (1945a) published the replacement name S. coffeae for S. falculatum , referring to a previous paper ( Vargas, 1943) in which he dealt with several names pertaining to this species. He supposed that S. falculatum (as F. f a l c u l a t a) was preoccupied by S. falcula (Enderlein, 1921) [as Wilhelmia falcula , misspelled as jalcula (see Crosskey & Howard, 1997)], a European species. Under the International Code of Zoological Nomenclature (1999:9, article 10.6), the name S. coffeae represents an unjustified replacement name because F. falculata and W. falcula are not homonyms.

In a paper on the supraspecific classification of Neotropical Simuliidae, Coscarón (1987) synonymised with doubt F. falculata with S. paynei Vargas and this has been followed by Crosskey & Howard (1997; 2004). More recently, Adler et al. (2004) in their treatment of S. paynei did not accept the name S. falculatum as a possible synonym of S. paynei due to its long claws, shiny frons and abdomen, and dark fore legs, which they said were not characteristic of any of the Hemicnetha species they had examined. They also suggested that the name S. falculatum represents a valid species, but were unable to make further comments due to the “absence of the terminalia on the type ”. We have examined a single female of S. falculatum in the NMHU collection. The specimen agrees with the locality information given by Enderlein (1934a), bears a handwritten label by Enderlein “ Friesia falculata Type Enderl. Ψ”, and printed at the bottom of the label “Dr. Enderlein det. 1928”. The specimen also has a label in Coscarón’s hand “ Simulium (Hemicnetha) paynei Vargas? det. Coscarón 85”. Based on this information, we are confident that this is the holotype of F. f a l c u l a t a and the material on which Coscarón (1987) first proposed his doubtful synonymy of this species with S. paynei , and it has been labelled accordingly. It has been pointed out to us by Prof. P.H. Adler that this specimen is different from the one sent as the type to Adler et al. (2004), and which upon return to the NMHU collection by these authors could not be located for our examination.

The holotype of S. falculatum is pinned through the middle of the thorax, and the abdomen is slightly contracted (Figs. 33, 34). We have dissected the head, wings, legs, and abdomen and mounted them on a slide. Digital images have been made of the holotype prior to and after dissection. All morphological characters of this species have been compared with digital images and identified material of S. paynei deposited in the BMNH. Simulium falculatum (Figs. 1, 2) is externally similar to S. paynei in having a dark brown to black thorax with 1+1 median and 1+1 sub­lateral pruinose bands, but is easily distinguished by the morphology of the cibarium and genitalia. The cibarium of S. falculatum has well developed cornuae and the central trough is weakly concave (Fig. 36), the gonopophyses are broadly subrectangular with anterior and internal margins slightly sclerotised (Fig. 50), the paraprocts are nearly the same length as the cerci and are not expanded apically (Fig. 64), and the genital fork has a long, narrow stem and lacks posterior triangular processes (Fig. 78). In S. paynei the cornuae of the cibarium are relatively less developed, the central trough is distinctly concave, the paraprocts are twice as long as the cerci and are expanded apically, the gonopophyses are distinctly triangular and the stem of the genital fork is relatively shorter with prominent triangular posterior processes (see Vargas & Díaz Nájera, 1957: 322, Figs. 231–238). Based on these morphological differences, we agree with Adler et al. (2004) that S. falculatum is a valid species.

Coscarón et al. (1987) and Crosskey & Howard (1997, 2004) regarded S. falculatum as a probable synonym of S. paynei within the subgenus Hemicnetha , while Adler et al. (2004) also included it in this subgenus, albeit as a valid species. Therefore, we maintain S. falculatum within the subgenus Hemicnetha as a valid species until the morphology of the male and immature stages is known. Simulium falculatum shares the female diagnostic characters of species within the subgenus Hearlea Vargas, Martínez Palacios & Díaz Nájera, as reviewed by Coscarón et al. (2004). It appears close to Simulium ayrozai Va rg as in scutal pattern and cibarial morphology, the two species being readily distinguished by the structure of the paraproct. We also compared S. falculatum with species descriptions and drawings in Dalmat (1955) and Vargas & Díaz Nájera (1957) and with specimens identified by Dalmat and Vargas in the BMNH (see “ Material examined”). The general structure of the paraproct of S. falculatum is similar to that of S. carolinae De León (as seen on slide material), but both species can be reliably identified by the structure of the genital fork. Simulium falculatum might be a synonym of one of the already described species of Hearlea, a subgenus that Adler et al. (2004) subsumed within the canadense species group of Hemicnetha . At this juncture we do not wish to comment on the status of Hearlea, leaving an opinion to a later date when we have made a more detailed examination of relevant species from Central America.