Pseudoceros agattiensis, Dixit & Bayyana & Manjebrayakath & Saravanane & Sudhakar, 2019

Dixit, Sudhanshu, Bayyana, Sharad, Manjebrayakath, Hashim, Saravanane, N. & Sudhakar, M., 2019, Polyclad fauna of Agatti Island, Lakshadweep, India: new records and description of two new species, Zootaxa 4657 (2), pp. 246-260 : 251-254

publication ID	https://doi.org/ 10.11646/zootaxa.4657.2.2
publication LSID	lsid:zoobank.org:pub:3708F04B-C342-464B-882E-583C4101C977
DOI	https://doi.org/10.5281/zenodo.3800375
persistent identifier	https://treatment.plazi.org/id/EC489EB5-985C-45B2-9335-85BC60EDFA66
taxon LSID	lsid:zoobank.org:act:EC489EB5-985C-45B2-9335-85BC60EDFA66
treatment provided by	Valdenar
scientific name	Pseudoceros agattiensis
status	sp. nov.

Treatment

Pseudoceros agattiensis sp. nov. Dixit

( Figs. 3 View FIGURE 3 , 4 View FIGURE 4 & 5 View FIGURE 5 )

Material examined: Holotype: One specimen (20 × 18 mm) as serial sections (10 Slides), remainder of animal in 70% ethanol. Collected on 12.5.2018, underneath rubble in intertidal area, Agatti Island (10°52′72′′N 72°12′12′′E), Lakshadweep, India. (Regn. No. IO /IT/POY/00005)

Type locality: Agatti Island , Lakshadweep, India .

Etymology: The specific name refers to Agatti Island in Lakshadweep, where type specimen was collected.

Diagnosis: Background body colour is brown in centre and fading to black towards the margin, covered with numerous white spots, densely arranged in the centre and sparse towards the margin. ( Fig. 3a View FIGURE 3 ). Three longitudinal stripes runs throughout the dorsal surface. Median stripe is thin without any branches while lateral stripes are branches towards the margin. These stripes are white in centre and light brown at most extremities with bulging ends. Pseudotentacles are simple folding of the anterior margin and black in colour. Cerebral eye cluster horseshoe shaped ( Fig. 3b View FIGURE 3 ).

Description: Live. Body small, oval and margin without ruffles. Background body colour brown to black. Numerous small white spots present all over dorsal surface except on the three stripes. Marginal band thick and black with minute white spots present at very edge of the margin ( Fig. 3a View FIGURE 3 ). These small white dots are very close which gives a very thin white rim like appearance. Dorsal surface patterned with three longitudinal stripes and its branches. Median stripe thin and without any branches, lateral stripes branched radiating towards margins. Lateral stripes are white in centre and light brown at most extremities with bulging ends. Some small bulged and incomplete stripes starting from margins towards median area ends abruptly before touching any stripe of either side. Pseudotentacles small and black. Cerebral eye cluster horseshoe shaped ( Fig. 3b View FIGURE 3 ), tentacular eyes hard to locate due to black colour of pseudotentacles. Ventral surface brown in colour.

Preserved. Specimen brown in colour after fixation. Ventrally dull brown in colour. Male and female pore are 0.8 mm apart, while female pore and sucker are 1.7 mm apart ( Fig. 3c View FIGURE 3 ). Pharynx ruffled with seven folds and male pore is situated very near to last pair of pharyngeal folds ( Fig. 3c View FIGURE 3 ). Pharynx is 2.9 mm long (measured externally) and distance between mouth and male pore is 1.4 mm. Cerebral eye cluster with about 50 -55 eyes.

Reproductive system: Male copulatory apparatus consists of seminal vesicle, free prostatic vesicle, penis papilla, penis stylet housed in male atrium which open outside via male pore. A large, elongated and thick walled seminal vesicle (574 x 315 µm) is present ( Fig. 4b, c View FIGURE 4 ). Its rounded part oriented towards prostatic vesicles while tapered part is oriented towards cement glands. An oblong and thick walled prostatic vesicle (187 x 91 µm) is present anterior of seminal vesicle ( Fig. 4b View FIGURE 4 ). Thickness of prostatic vesicle’s wall varies from 10 to 15 µm. Male atrium conical ( Fig. 4d View FIGURE 4 ) housing conical penis papilla (170 µm) with a short stylet (87 µm). The ejaculatory duct and the prostatic duct joins before entering the penis papilla ( Fig. 4b View FIGURE 4 ). Male atrium opens to exterior via male gonopore. Female copulatory apparatus consists of oviducts, vagina, cement pouch surrounded by numerous cement glands and female atrium. The vagina opens to a short female atrium via cement pouch which receives secretion from cement glands.

Taxonomic remarks: Presence of ruffled pharynx, male copulatory apparatus just behind pharyngeal cavity, free prostatic vesicle, marginal tentacles formed by upfolding of anterior margin, centrally located sucker behind female pore ( Faubel 1984) places Pseudoceros agattiensis sp. nov. in the family Pseudocerotidae while presence of characters such as smooth dorsal surface, single male copulatory apparatus with seminal vesicle ( Fig. 4a View FIGURE 4 ) and armed penis papilla, pseudotenctacles as simple folds of anterior margin, female pore equidistant from male pore and sucker ( Faubel 1984; Newman and Cannon 1998) place this newly described species in the genus Pseudoceros . There are only few species in genus Pseudoceros which displays transverse streaks on dorsum namely Pseudoceros felis Neman and Cannon, 1994 , Pseudoceros mororum Cuadrado, Moro and Norena, 2017 ; Pseudoceros zebra ( Leuckart, 1828) ; Pseudoceros sp. 14 (see Neman and Cannon 2003; pg 79); Pseudoceros sp. 24 (see Neman and Cannon 2005) and Pseudoceros sp. 42 (see Neman and Cannon 2005). Pseudoceros felis is grey brown in colour with white to cream transverse streaks and spots which clearly differentiate it from Pseudoceros agattiensis sp. nov. Pseudoceros zebra have white streaks with black markings and yellow marginal band which differentiates it with newly described species. Pseudoceros sp. 14 is the fairly closest example we could find from the genus Pseudoceros in terms of colour and streaks, however no information is known about ventral surface or number of pores, so further comparison would be unclear and vague. Pseudoceros agattiensis sp. nov. can be readily distinguished from other congeners in terms of colour, arrangement and patterns of transverse streaks. The newly described species is a perfect example for importance of careful observation of colours and patterns especially among pseudocerotids. If not observed carefully, the newly described species can easily be confused with juvenile of Pseudobiceors bedfordi . A similar looking juvenile was photographed by Scott Johnson in Marshall Islands ( Newman and Cannon 2005). Both species at first instance looks quite similar and can only be differentiated by careful examination of external characters (number of male pores) and colour patterns. Based on above mentioned characters and comparisons, we establish Pseudoceros agattiensis sp. nov. as new species to science.