Obama tribalis, Marques & Rossi & Valiati & Leal-Zanchet, 2018

Marques, Alessandro, Rossi, Ilana, Valiati, Victor Hugo & Leal-Zanchet, Ana Maria, 2018, Integrative approach reveals two new species of Obama (Platyhelminthes: Tricladida) from the South-Brazilian Atlantic Forest, Zootaxa 4455 (1), pp. 99-126 : 119-120

Obama tribalis sp. nov.

By having yellOwish dOrsal cOlOur cOvered by irregular flecks, O. tribalis differs frOm O. argus , O. burmeisteri , O. evelinae and O. riesteri which shOw a stripped pattern ( Graff 1899; Schirch 1929; Riester 1938; Marcus 1951). Obama tribalis , shOwing a greyish ventral cOlOur, can be distinguished frOm O. itatiayana , which has reddish ventral cOlOur. In additiOn, O. tribalis shOws incOnspicuOus clear halOs surrOunding the eyes, whereas in O. polyophthalma clear halOs are cOnspicuOus, as stated abOve ( Schirch 1929; EM FrOehlich 1955; FrOehlich 1959).

Regarding the internal anatOmy, in O. tribalis the penis papilla Occurs Only inside the male atrium, thus differing frOm O. burmeisteri and O. riesteri , in which the penis papilla is lOnger, Occupying almOst the entire female atrium length ( Riester 1938; Marcus 1951). In additiOn, O. riesteri shOws a shOrt male atrium, with the gOnOduct clOser tO the insertiOns Of the penis papilla ( Riester 1938), whereas in O. tribalis the male atrium length is similar tO that Of the female atrium. By having an OvOid and fOlded female atrium, O. tribalis can be distinguished frOm O. argus and O. itatiayana , in which the female atrium is funnel-shaped and unfOlded ( Graff 1899; Schirch 1929; Riester 1938; FrOehlich 1959) and O. polyophthalma , in which the female atrium has an ample cavity ( FrOehlich 1956). Since O. tribalis has a straight ejaculatOry duct, it differs frOm O. evelinae , which shOws a sinuOus ejaculatOry duct (Marcus 1951).

Obama tribalis differs frOm O. allandra by its external features and details Of the cOpulatOry Organs. AlthOugh bOth species exhibit part Of the dOrsal surface cOvered by irregular flecks, O. allandra , by shOwing a yellOwish median band, which is lighter On anteriOr regiOn Of bOdy, can be distinguished frOm O. tribalis , which shOws a hOmOgeneOusly yellOwish dOrsal cOlOur. With respect tO the cOpulatOry apparatus, bOth species present a prOstatic vesicle with fOrked prOximal pOrtiOn, but the distal pOrtiOn is pear-shaped in O. tribalis , whereas it is wide and inverted-U shaped in O. allandra . SOme details Of the cOpulatOry apparatus, such as the Occurrence Of glands Of the mixed type, Opening intO an invaginatiOn Of the dOrsOlateral wall Of the male atrium in O. allandra , are absent in O. tribalis .

In additiOn, we extend Our cOmparative analysis Of O. allandra and O. tribalis tO species Of Geoplana incertae sedis, since sOme Of them have general characteristics similar tO species Of Obama . AmOng the 47 species indicated by CarbayO et al. (2013) as Geoplana incertae sedis, Only fOur species shOw characteristics Of the pharynx and cOpulatOry apparatus similar tO thOse Of O. allandra and O. tribalis . They are Geoplana beckeri ( FrOehlich, 1959) , Geoplana caya (du BOis-ReymOnd Marcus, 1951), G. hina (Marcus, 1951) and G. toriba ( FrOehlich, 1958) . By presenting a median band Only in the anteriOr regiOn Of the bOdy, O. allandra differs frOm G. hina and G. toriba , which shOw a stripped pattern alOng the entire bOdy length (Marcus 1951; FrOehlich 1958). Obama allandra shOws initially marginal eyes, which becOme dOrsal pOsteriOrly, differing frOm G. beckeri , which has dOrsal eyes On the anteriOr tip. It alsO differs frOm G. caya , which has Only marginal eyes ( FrOehlich 1959; du BOis-ReymOnd Marcus 1951). By having a yellOwish dOrsal cOlOur withOut stripes Or bands, O. tribalis differs frOm all these species Of Geoplana incertae sedis, which have striped patterns. With respect tO the cOpulatOry Organs, O. allandra presents a distal pOrtiOn Of prOstatic vesicle inverted-U shaped and wide, differing frOm these fOur species, which have the distal pOrtiOn Of prOstatic vesicle tubular in shape (du BOis-ReymOnd Marcus 1951; Marcus 1951; du BOis- ReymOnd Marcus 1958; FrOehlich 1958). Obama tribalis , by having the unfOrked pOrtiOn Of the prOstatic vesicle pear-shaped, can be distinguished frOm these fOur species, which have the prOstatic vesicle tubular shaped and sinuOus (du BOis-ReymOnd Marcus 1951; Marcus 1951; du BOis-ReymOnd Marcus 1958; FrOehlich 1958).

Regarding the mOlecular phylOgeny herein presented, based On the mitOchOndrial marker cytOchrOme c Oxidase subunit I gene (COI), likelihOOd and Bayesian analyses invariably recOvered the terminal clades with mOderate and gOOd suppOrt values. HOwever, the segment Of the COI gene used in the analyses demOnstrated a lack Of sufficient infOrmatiOn tO sOlve mOst relatiOnships between the clOsely related cOngeneric species. This result was expected, since the COI gene dOes nOt shOw gOOd resOlutiOn at higher taxOnOmic levels (LuO et al. 2011; Huang et al. 2013). Our results indicate the need tO use at least 600 bp Of the gene COI in the definitiOns Of interspecific divergences and fOr species delineatiOn, at least fOr the genus Obama . COnsidering length limitatiOn tO determine the threshOld taxOnOmic, the shOrt sequences Of O. marmorata available On GenBank (297 pb) were insufficient tO determine the taxOnOmic divergence with O. nungara , clOsely related species.