Bisacculosuteri, Ramos-Sánchez & Bahia & Bastida-Zavala, 2019

Ramos-Sánchez, Mariela, Bahia, Juliana & Bastida-Zavala, J. Rolando, 2019, New genus, new species and new records of marine acotylean flatworms (Platyhelminthes: Polycladida: Acotylea) from Oaxaca, southern Mexican Pacific, Zootaxa 4700 (1), pp. 30-58 : 30-58

Bisacculosuteri gen. nov.

http://zoobank.org/NomenclaturalActs/01524840-c2e3-4826-a15e-302b5fb25fc6

Type species. Bisacculosuteri marcelae sp. nov. Ramos-Sánchez, Bahia & Bastida-Zavala , 2019 .

Diagnosis. Leptoplanidae with oval to circular body; cerebral and tentacular eyes; without marginal eyes; pyriform nuchal tentacles; pharynx folded, distributed in a circular manner in the central region of the body; male reproductive system with prostatic vesicle interpolated poorly differentiated (e.g., no clear separation between the seminal vesicle and the prostatic vesicle); oval and prominent seminal vesicle; spermiducal vesicles present; sclerotized stylet cylindrical with acicular tip; female reproductive system with a uterine duct; a paired uterine sac; ovoid and strongly muscularized uterine vesicles; muscularized vaginal pore, located posteriorly to the female gonopore; a vaginal duct; oval Lang´s vesicle and duct of Lang´s vesicle poorly developed.

Etymology. The generic name was applied taking into account the possession of a double uterine sac in the female reproductive system.

Taxonomic remarks. Leptoplanidae is a family composed by eight genera: Leptoplana Ehrenberg, 1831 ; Hoploplana Laidlaw, 1902 ; Haploplana Bock, 1913 ; Notoplanides Palombi, 1928 ; Indiplana Strummer-Traunfels, 1933 ; Itannia Marcus, 1947 ; Longiprostatum Hyman, 1953 ; Parviplana Hyman, 1953 ; Leptoplanella Faubel, 1983 and Bivesiculoplana Pineda-López & González-Bulnes, 1984. A new species of Leptoplanidae discovered in Oaxaca was not possible to determined in any of these genera.

Bisacculosuteri gen. nov. belongs to Leptoplanidae by virtue of lacking marginal eyes, ruffled pharynx central of the body; male reproductive system directed backwards behind the pharyngeal cavity; gonopores separate; prostatic vesicle poorly differential, covered by a smooth glandular epithelium, without distinct muscle wall, lacking accessory prostatic vesicles but with a seminal vesicle.

The genus Itannia is most similar to Bisacculosuteri gen. nov., with which it shares some external features such as a similar body shape, nuchal tentacles, cerebral and tentacular eyes, and pharynx morphology; however, it differs from Itannia by the morphology of the reproductive system and because Itannia has a paired ventral sucker in both sides of the female gonopore ( Marcus 1952; Du Bois-Reymond Marcus 1957; Faubel 1983), a character lacking in Bisacculosuteri gen. nov.

Bisacculosuteri gen. nov. differs from Leptoplana because the former has nuchal tentacles and lacks a sucker, or genital pit, between male and female gonopores; while Leptoplana does not have tentacles and has a sucker between male and female gonopores ( Ehrenberg 1831; Faubel 1983).

Bisacculosuteri gen. nov. differs from Hoploplana because the former has a conspicuous seminal vesicle, a character absent in Hoploplana (Laidlaw 1908; Faubel 1983).

Bisacculosuteri gen. nov. differs from Indiplana because the latter genus lacks nuchal tentacles and has tripartite vesicle that consists of a prostatic-like ejaculatory duct and spermiducal bulbs (Strummer-Traunfels 1933; Faubel 1983), while Bisacculosuteri gen. nov. has nuchal tentacles, and the vesicle is interpolated and poorly differentiated.

Bisacculosuteri gen. nov. differs from Longiprostatum mainly in the arrangement of the eyes: Longiprostatum has cerebral-frontal eyes groups and marginal eyes ( Hyman 1953a; Faubel 1983), while Bisacculosuteri gen. nov. has cerebral and tentacular eyespots, and has no marginal eyes.

Bisacculosuteri gen. nov. differs from Parviplana since this genus lacks nuchal tentacles and stylet ( Hyman 1953a; Faubel 1983), both characters present in Bisacculosuteri gen. nov.

Leptoplanella has a cuneate body, prominent nuchal tentacles and lacks Lang´s vesicle ( Faubel 1983), while Bisacculosuteri gen. nov. has a circular body, shorter nuchal tentacles and a Lang’s vesicle.

Bisacculosuteri gen. nov. presents a simple Lang´s vesicle and a prominent seminal vesicle, while Bivesiculoplana lamothei presents a paired Lang’s vesicle and a rudimentary seminal vesicle. Both genera also differ in the type of habitat: B. lamothei is an ectocommensal species of limpets ( Pineda-López & González-Bulnes 1984), while Bisacculosuteri gen. nov. is associated with seaweed.

The genera Haploplana and Notoplanides are included within the family; however, their type species were transferred to the genus Euplanoida Faubel, 1983 , of the Superfamily Ilyplanoidea, and to the genus Stylochoplana ( Stimpson, 1857) of the Superfamily Leptoplanoidea, respectively ( Faubel 1983; Prudhoe 1989); thus, both genera should be redefined. Bisacculosuteri gen. nov. differs from Haploplana because the later genus lacks an armed penis papilla and nuchal tentacles ( Bock 1913; Faubel 1983), while Bisacculosuteri gen. nov. has both characters. On the other hand, the genus Notoplanides has an unarmed penis papilla, an elongated body and prominent nuchal tentacles ( Palombi 1928; Faubel 1983), while Bisacculosuteri gen. nov. has an armed penis papilla, an oval/circular body and the nuchal tentacles are rudimentary.

Considering all these differences from the other genera of the family Leptoplanidae , Bisacculosuteri gen. nov. is established.