Redescription of Petasiger exaeretus Dietz, 1909 and P. phalacrocoracis (Yamaguti, 1939) (Trematoda: Echinostomatidae), parasites of cormorants

Abstract

Two echinostome trematodes of the genus Petasiger, P. exaeretus Dietz, 1909 and P. phalacrocoracis (Yamaguti, 1939), parasitising cormorants (Phalacrocoracidae), were found in Phalacrocorax carbo L. from the Czech Republic. Both taxa are redescribed and literary data on their occurence in cormorants are reviewed. The species P. exaeretus appears to be a rather rare species, hitherto recorded in Phalacrocorax carbo in Europe, Kirghizia and Azerbaidzhan. P. baschkirovi Ablassov & Iksanov, 1959 is synonymized with P. exaeretus. P. phalacrocoracis (syn. P. hospitale (Mendheim, 1940) and P. exaeretus auct. nec Dietz, 1909), which has previously been misidentified and erroneously designated as P. exaeretus, appears to be the commonest species of the genus, parasitising cormorants in the Palaearctic Region (Europe, CIS [USSR], Japan) and in Australia. Differential diagnoses of both the above mentioned species are presented.

A revision of Petasiger Dietz, 1909 (Digenea: Echinostomatidae) and a key to its species

“…These authors listed the following as the most characteristic distinguishing features of P. exaeretus: (i) a large, pear-shaped body; (ii) a ventral sucker located near to the mid-body (post-equatorial or equatorial); (iii) the absence of a prepharynx; (iv) large angle spines (up to 125 lm in length); (v) the vitellarium extending forward to the level of intestinal bifurcation; and (vi) numerous eggs. Našincová et al (1994) considered P. baschkirovi Ablasov & Iksanov, 1959 to be a junior synonym of P. exaeretus, an action with which we agree (see Table 1 for comparative metrical data). Ku et al (1977) described P. tientsinensis Ku, Chiu, Li & Zhu, 1977 from T. ruficollis poggei in China.…”

“…Našincová, Scholz & Moravec (1994) provided detailed redescriptions of both P. exaeretus and P. phalacrocoracis, on the basis of newly collected material, and critically reviewed the existing records of Petasiger in cormorants. These authors listed the following as the most characteristic distinguishing features of P. exaeretus: (i) a large, pear-shaped body; (ii) a ventral sucker located near to the mid-body (post-equatorial or equatorial); (iii) the absence of a prepharynx; (iv) large angle spines (up to 125 lm in length); (v) the vitellarium extending forward to the level of intestinal bifurcation; and (vi) numerous eggs.…”

The occurrence of metacercariae of Petasiger (Digenea: Echinostomatidae) in an unusual site, within the lateral line scales of cyprinid fishes

“…It is clear that molecular data are needed for more adult echinostomatids in order to solve this problem. This applies especially of Petasiger exaeretus, which is less frequently found than P. phalacrocoracis (see Našincová et al 1994), since there are only two known species of Petasiger with 27 collar spines reported from Europe (Faltýnková et al 2008). Nevertheless, it should be noted that enlarged mid-dorsal spines were not reported in the adult of this species by Našincová et al (1994).…”

“…phalacrocoracis (Yamaguti, 1939), both parasites of cormorants Phalacrocorax spp. According to Našincová et al (1994), P. phalacrocoracis differs from P. exaeretus in relation to its smaller collar spines.…”

“…relates to the adult stage (Našincová et al 1994, Kostadinova et al 2005, Faltýnková et al 2008 and their life cycles (Karmanova 1971, Kostadinova and Chipev 1992, King and Van As, 2000, Georgieva et al 2012. Useful data on the metacercarial stage in their fish second intermediate hosts have been presented by Karmanova (1971) and Georgieva et al (2012).…”