Pseudoceros meenae, Dixit & Sivaperuman & Raghunathan, 2018

Dixit, Sudhanshu, Sivaperuman, C. & Raghunathan, C., 2018, Description of two new pseudocerotids (Rahabditophora: Rhabditophora; Polycladida) from Andaman & Nicobar Islands, India, Zootaxa 4403 (2), pp. 365-377 : 367-369

Pseudoceros meenae sp. nov.

( Figures 2–4 )

Type material. Holotype: One specimen (13 × 7 mm) as serial sectiOns Of reprOductive structures (6 slides) and remainder Of animal in 70% ethanOl. COllected On 20.02.2014, underneath rubble in intertidal area, Kalapathhar (10°39.356’ N 92°34.794’ E), Hut Bay , Little Andaman, India; RegistratiOn NO.—ZSI/ANRC-17792.

Paratypes: One specimen (11 × 6 mm) in 70% ethanOl. COllected On 0 9.02.2016, underneath rubble in intertidal area, B. Quarry (07°00.205’N 093°56.974’E), Great NicObar Island , India; RegistratiOn NO.—ZSI/ ANRC-17793).

One specimen (12 × 6 mm) in 70% ethanOl. COllected On 0 9.02.2016, underneath rubble in intertidal area, B. Quarry (07°00.205’N 093°56.974’E), Great NicObar Island , India; RegistratiOn NO.—ZSI/ANRC-17794).

Distribution. Andaman and NicObar Islands, India. AdditiOnal phOtOgraphic recOrd frOm Marshall Islands and Papua New Guinea ( Newman & CannOn, 2003 & 2005). This species has alsO been Observed On ReuniOn and MayOtte Islands (http://seaslugs.free.fr/flatwOrm/planaire/ pseudOcerOs _cf_cOnfusus_a.htm)

Diagnosis. BackgrOund bOdy cOlOur white with three marginal bands; inner black, middle Orange and an OutermOst white rim. PseudOtenctacles small with a black Outer bOrder.

Etymology. The specific name refers tO first authOr’s mOther, Meena Dixit, fOr her cOnstant suppOrt and inspiratiOn.

Description. Live. BOdy s mall, smOOth, slightly elOngated, and terminally rOunded. BackgrOund cOlOur with three distinct marginal bands; inner narrOw black fOllOwed by middle brOad Orange and a white Outer rim. Margin slightly ruffled. The pseudOtentacles are small simple fOlds On anteriOr margin, with three marginal bands present: an innermOst black, fOllOwed Outrwards by an Orange and an OutermOst black rim. Cerebral eyespOts cluster with 40-44 eyes. Ventrally white in cOlOur.

Preserved. Specimen translucent due tO lOss Of cOlOur during the cOurse Of fixatiOn but black and Orange marginal bands are quite decipherable. BOdy wall thickness is 32–39 µm fOr dOrsal and 15–25 µm fOr ventral epidermis. Distance between mOuth and sucker is 2.7 mm. Male and female gOnOpOres 0.6 mm apart frOm One anOther while male pOre and sucker are 1.5 mm apart. Pharynx small and ruffled with 8 fOlds. Male pOre 1.2 mm frOm mOuth and is situated between last fOlds Of pharynx.

Reproductive characters. Seminal vesicle ( Fig.3.A&B ) elOngated and heavily mascularized (556 × 324 µm), thick walled, tapering tOwards anteriOr margin and slightly parallel tO lOngitudinal bOdy axis. Its lumen is lined by ciliated epithelium with nuclei at periphery. PrOstatic vesicle ( Fig.3.D ) small and rOund (174 × 129 µm), lOcated slightly left frOm median line abOve male atrium and near tapered part Of seminal vesicle. The granular epithelial lining is 25–30 µm thick surrOunded by 9–11 µm thick distinct muscular layer. Male atrium inverted U-shaped and deep with hOusing a penis 240 µm ( Fig.3.B ) lOng and Opening ventrally by a wide male gOnOpOre. Female atrium ( Fig.3C ) clearly visible and 169 µm lOng fOllOwed by cement pOuch and vagina which lead tO uterus via Oviduct. Dense cement glandular cells visible arOund female atrium and vagina.

Taxonomic remarks. Presence Of ruffled pharynx, male cOpulatOry apparatus just behind pharyngeal cavity and free prOstatic vesicle ( Faubel, 1984) places Pseudoceros meenae sp. nov. in the family PseudOcerOtidae while presence Of characters such as One male pOre, simple fOlds fOrming pseudOtentacles, ruffled, rOund and Oval pharynx (butterfly shape), equal distance between sucker and gOnOpOres, ( Faubel, 1984; Newman & CannOn, 1998) place this newly described species in the genus Pseudoceros . We believe that this new species belOngs tO the species-cOmplex Of Pseudoceros bimarginatus Meixner, 1907 . Other species belOnging tO this grOup are: P. confuses , P. contrarius and P. intermittus . These species lOOks very much similar tO each Other in terms Of backgrOund cOlOur and marginal bands and accurate determinatiOn can be Only be carried Out if the cOlOur and cOlOur pattern are dOcumented with clOse examinatiOn in detail ( Newman & CannOn, 1995). Pseudoceros meenae sp. nov. is differentiated frOm all abOve mentiOned species On the basis Of arrangement Of marginal bands and absence Of median line ( Table 1). HOwever, in Original descriptiOn Of P. intermittus , nO presence Of median line was mentiOned by the authOrs ( Newman & CannOn, 1995) while the pictures published in Newman & CannOn (2003; Pg. 41 & 75) clearly shOws presence Of a faint white median line which can be a pOssible variatiOn. Pseudoceros stimpsoni Newman & CannOn, 1998 alsO have three marginal bands made up Of black fOllOwed by Orange and again fOllOwed by black band which is different frOm newly described species with black fOllOwed by Orange band with white rim. The cOlOur Of dOrsum (brOwn-grey) alsO differentiates it frOm the newly described species here. The general mOrphOlOgy Of the bOdy as well as the cOlOur pattern: white backgrOund cOlOur with three marginal bands Of P. meenae sp. nov. agrees with the specimens frOm ReuniOn and MayOtte Island (see distributiOn fOr mOre metails) and Pseudoceros sp. 8 ( Newman & CannOn 2003, p.79 and 2005, CD-ROM). Newman & CannOn (2005) repOrted this species as undescribed and rare.

Figures

FIGURE 2. A—Pseudoceros meenae sp.nov. ex situ from Hut Bay (Holotype—ZSI/ANRC-17792); B—dorsal surface; Cventral surface; D—Cerebral eyes; E—Pseudotentacular eyes. fp: female gonopore; in: intestine; mp: male gonopore; p: pharynx; su: sucker. Scales—A: 1mm; B & C: 2mm; D: 200 µm; E: 500 µm.

FIGURE 3. Pseudoceros meenae sp. nov. (Holotype—ZSI/ANRC-17792); A—sagittal section; B—male reproductive system; C—female reproductive system; D—prostatic vesicle; E—intestine and epidermal layers. Abbreviations: bm: basement membrane; cg: cement glands; cm: circular muscles; cp: cement pouch; ep: epidermis; fa: female atrium; fp: female gonopore; in: intestine; ma: male atrium; mp: male gonopore; pp: penis papilla; pv: prostatic vesicle; st: stylet; su: sucker; sv: seminal vesicle; ut: uterus; va: vagina. Scales—A: 500 µm; B–E: 200 µm.

FIGURE 4. Pseudoceros meenae sp. nov. (Holotype—ZSI/ANRC-17792); Diagrammatic reconstruction of male and female reproductive system. bm: basement membrane; cg: cement glands; cm: circular muscles; cp: cement pouch; ed: ejaculatory duct; ep: epidermis; fa: female atrium; fp: female gonopore; in: intestine; ma: male atrium; mp: male gonopore; pd: prostatic duct; pp: penis papilla; pv: prostatic vesicle; st: stylet; sv: seminal vesicle; ut: uterus; va: vagina.