Cyclocoelum petrowi, Kurashvili, 1953

Dronen, Norman O. & Blend, Charles K., 2015, Updated keys to the genera in the subfamilies of Cyclocoelidae Stossich, 1902, including a reconsideration of species assignments, species keys and the proposal of a new genus in Szidatitreminae Dronen, 2007, Zootaxa 4053 (1), pp. 1-100 : 85

Skrjabinocoelum petrowi Kurashvili, 1953 — Type and only species

Type host. Jack snipe, Lymnocryptes minimus (Brunnich) ( Charadriiformes : Scolopacidae ).

Type locality. Gruziia, Georgia (country); specific type locality unknown.

Additional host. Common snipe, Gallinago gallinago (Linnaeus) ( Charadriiformes : Scolopacidae ).

Additional localities. Republic of Azerbaidzhan, specific locality unknown; vicinity of Senné, Slovakia— Feizullaev (1980).

Remarks. Based on the apparently unique morphology (configuration of the intertesticular ovary forming a straight horizontal line with the side by side testes; anterior confluence of the vitelline fields), Dronen (2007a) erected Skrjabinocoelinae Dronen, 2007 to accommodate this species. It is currently the only species in the subfamily. Admittedly, S. petrowi is a rare species; Macko et al. (2011) found only a single, larger (16,000 long compared to 11,000 in the type specimen; likely older) specimen from one of 33 jack snipe collected from Slovakia that by all indications is the species described by Kurashvili (1953). The anterior end of the specimen in this most recent description appears to be contracted, somewhat like the specimen shown in the original figure by Kurashvili (1953), which in both cases may have influenced the placement of the genital pore (see later discussion regarding the tendency of contraction of the anterior end for cyclocoelids that commonly occurs even in appropriately-fixed specimens). The genital pore in S. petrowi appears to be submedian opening about the midlevel of the pharynx; however, in either of these specimens, the genital pore would likely be considered to be prepharyngeal ( Kanev et al. 2002a). In the specimen of Macko et al. (2011), the ovary is posttesticular and forms a triangle with the slightly oblique testes, which would place this species in Szidatitreminae Dronen, 2007; possibly in Pseudoszidatitrema n. gen. proposed herein for species where the genital pore is prepharyngeal and the vitelline fields are confluent posteriorly. Feizullaev (1980) indicated that this species also has been found in the common snipe from the Republic of Azerbaidzhan. Skrjabinocoelum petrowi is somewhat similar to species of Circumvitellatrema Dronen, Greiner, Jaleggio & Nolan, 2009 by having the vitelline fields confluent both posteriorly and anteriorly. As discussed later, whenever a species is described based on very small sample sizes, we do not get an accurate idea of the intraspecific variation of it, and without more specimens a reasonable determination of the taxonomic status of this species cannot be made. No oral or ventral sucker present—Kurashvili (1953); Macko et al. (2011).