Pseudoceros bifascia, Dixit & Sreeraj, 2024

Dixit, Sudhanshu & Sreeraj, Chemmencheri Ramakrishnan, 2024, Two new polyclad (Platyhelminthes: Polycladida) flatworm species from the Lakshadweep Islands, India, Zootaxa 5446 (3), pp. 405-419 : 413-416

publication ID	https://doi.org/ 10.11646/zootaxa.5446.3.5
publication LSID	lsid:zoobank.org:pub:531387F2-B008-40B6-9621-C1A2B5E8ACF0
DOI	https://doi.org/10.5281/zenodo.11101973
persistent identifier	https://treatment.plazi.org/id/070F0561-2910-FFE2-5EE1-849BFE84FE0F
treatment provided by	Plazi
scientific name	Pseudoceros bifascia
status	sp. nov.

Treatment

Pseudoceros bifascia sp. nov.

( Figures 5−7 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Type material

Holotype (10 x 6 mm): as sagittal sections; Regn. No. ZSI/WGRC/I.R.-Inv.22072; reproductive structures in seven slides; Agatti Island (10°52’5.79”N, 72°12’12.64”E; Lakshadweep, India; Near Eastern Jetty , Oct 27, 2019, Coll. Sreeraj C.R.) GoogleMaps

Other material: One specimen, damaged during the course of tissue collection for DNA studies (specimen became very soft after coming in contact with ice and was damaged beyond recognition). 10 mm approx., used for DNA studies (no result), photographs used for colour determination.

Etymology

The specific name refers to the presence of two-coloured bands (black and orange) on pseudotentacles ( Fig. 2B, E View FIGURE 2 ) i.e., two (bi in Latin) and band (fascia in Latin).

Type Locality

Agatti Island (10°52’5.79”N, 72°12’12.64”E), Lakshadweep, India.

Description

Live: Body small (15mm x 8 mm) and oval with smooth margin. White background colour with black pattern on the dorsum; thin interrupted orange marginal band followed by a wide white rim ( Fig. 5A, B View FIGURE 5 ). A thin longitudinal stripe line runs from cerebral eyespot cluster to the posterior end without touching the orange marginal band ( Fig. 5A, B View FIGURE 5 ). Pseudotentacles black-tipped, followed by an orange band and are simple folding of the anterior margin. Cerebral eye cluster horseshoe-shaped. Ventral surface cream in colour.

Preserved: Specimen yellowish after fixation ( Fig. 5C View FIGURE 5 ). Male and female gonopores 0.7 mm apart; female gonopore and sucker 0.9 mm apart ( Fig. 5D View FIGURE 5 ). Pharynx 2.2 mm long, ruffled with six to seven folds. Male gonopore situated very close to last pair of pharyngeal folds ( Fig. 5D View FIGURE 5 ), and 4.4 mm from anterior margin. Cerebral eye cluster with ~45–50 eyes ( Fig. 5E View FIGURE 5 ). Ventral tentaclular eyes distributed in limited area ( Fig. 5F View FIGURE 5 ). Dorsal epidermis thick in comparison to ventral epidermis; dorsal epidermis thickness 47 to 51 µm; ventral epidermis 5 to 8 µm thick.

Male reproductive system single, consists of ventrally scattered testes ( Fig. 6C View FIGURE 6 ), seminal vesicle, free prostatic vesicle, penis papilla in thick penis sheath housed in male atrium, which opens to the outside via male gonopore ( Fig. 6A View FIGURE 6 ). An elongated slender-shaped, thick-walled seminal vesicle present, 470 µm long and 210 µm wide at widest point ( Fig. 6A, B View FIGURE 6 ). Oval, thin-walled prostatic vesicle, 183µm long and 85 µm wide, present anterior to the seminal vesicle ( Fig. 6B View FIGURE 6 ). Prostatic vesicle with smooth granular epithelial lining, ~3 to 5 µm thick. Male atrium simple without folds ( Fig. 6B View FIGURE 6 ) housing unarmed conical penis papilla surrounded by thick penis sheath ( Fig. 6B View FIGURE 6 ).

Female reproductive system consists of dorsally scattered ovaries ( Fig. 6C View FIGURE 6 ), oviducts, vagina, cement pouch surrounded by numerous cement glands and female atrium ( Fig. 6B View FIGURE 6 ). Vagina oriented towards the posterior body region, connecting to the oviducts ( Fig. 6B View FIGURE 6 ). Vagina opens to short female atrium via cement pouch, which receives the secretion from cement glands. Female atrium opens to the exterior via female gonopore ( Fig. 6B View FIGURE 6 ).

Taxonomic remarks

The colour pattern of Pseudoceros bifascia sp. nov. is distinct (white background with irregular black pattern; fluorescent longitudinal stripe and margins made up of interrupted orange band and white rim) thus, differentiating it from other congeners. However, three species, viz. Ps. scintillatus Newman & Cannon, 1994 , Ps. scriptus Newman & Cannon, 1998 and Ps. zebra ( Leuckart, 1828) possess colours of orange/yellow, black and white but are different in arrangement and patterns.

Pseudoceros scintillatus has a velvety black background with irregularly sized yellow-green maculae encircled with white and has an orange marginal band while Ps. bifascia sp. nov. has white background with an interrupted orange marginal band followed by wide white rim.

Pseudoceros scriptus has a cream-yellow background with black irregular maculae on the dorsum; white near the margin followed by an orange rim, but Ps. bifascia sp. nov. has an interrupted orange marginal band followed by wide white rim.

Pseudoceros zebra has a white background with irregular black bands or patches; wide yellow marginal band interrupted by white markings while Ps. bifascia sp. nov. though have white background and black patches, its marginal band is orange followed by a wide white rim.

In addition, the newly described species features a simple male atrium as opposed to the folded male atrium of Ps. scintillatus and Ps. scriptus . A specimen comparable to Ps. bifascia sp. nov. was photographed in the Red Sea ( Pseudoceros sp. 19, Newman & Cannon 2003, Pg. 80 & 2005) and there has been no record of any similar specimen in literature or in any websites after then. This species was considered rare by Newman & Cannon (2003, pg. 80 & 2005). Thus, in light of the above-mentioned characters and comparisons, we describe Pseudoceros bifascia as new species to science.