Cycloporus decoratus Pitale & Apte 2021, sp. nov.

Cycloporus decoratus sp. nov.

(Figure 2, 3)

Etymology: Name derived from the Latin word decoratus meaning adorning or beautified, referring to the beautiful dorsal pattern of the species.

Material examined: Holotype: One specimen (BNHS-Pclad 300, 6.30 mm x 7.20 mm) in ethanol 80% and serial sagittal sections of the reproductive structures (148 slides). Collected 20-1-2019 at type locality Haji Ali Bay (18.980672° N, 72.805896° E), Mumbai, Maharashtra.

Paratype: One specimen (BNHS-Pclad 301, 3.70 mm x 4.26 mm), collected on 20-01-2019 at Haji Ali Bay, Mumbai; One specimen (BNHS-Pclad 395, 5.30 mm x 3.94 mm) collected on 6-03-2020 at Mandvi (16.988357° N, 73.274498° E), Ratnagiri.

Other material examined: A single specimen was first collected from Alawa, Ratnagiri; BNHS Pclad-0174, on 21-11-2014, intact but turned hard after preservation.

Distribution: Haji Ali Bay, Mumbai; Alawa and Mandvi, Ratnagiri, Maharashtra.

Diagnosis: Body translucent, appears brown-ochre due to intestinal branches; the entire dorsal surface is covered with light buff-tinged papillae; white star-like markings are prominent and give a mesh-like appearance. Five- Six lateral intestinal branches.

Description:

Colour: The translucent body appears brownish ochre dorsally due to the colouration of ramified intestinal branches (Figures 2A–E). The entire dorsal surface is covered with rounded buff pale, raised papillae that do not extend to the margin. Star-like or cross-like markings formed due to small intersecting white streaks adorning the dorsal surface, even on pseudotenatcles (Figures 2B, E and F). These prominent markings, placed compactly, give a mesh-like appearance until they reach the marginal band where their arrangement is loosened. The marginal band is translucent, with traces of brick-red colouration, rimmed by a distinct string of white dots. Widely spaced pseudotentacles translucent except for the presence of a white dotted rim and white cross streaks. Few rounded black dots are seen dispersed over the dorsal surface (Figures 2A, D, F, G). The translucent ventral surface imparts colour due to brownish intestinal branches (Figure 2H).

Form: Oval-discoid

Pseudotentacles: Small bumps, flattened (Figures 2D, E and G), measuring 0.43mm

Eyespots: Cerebral eyespots arranged in two elongated quadrangle clusters, 1.05 mm away from the anterior margin, 32 in each cluster. Tentacular eyespots with two dorsal and ventral clusters, ranging between 40–50 dorsally and 50–55 ventrally (Figure 2G, H).

Digestive system: Pharynx small tubular 0.5 mm long and mouth situated about 1.50 mm away from the anterior margin. The main branch of the intestine 2.25 mm long with five-six lateral branches (Figure 2G, H).

Gonopores: One male gonopore present behind the pharynx at a distance of 1.91 mm from the anterior margin, measuring 0.2 mm. One female gonopore 0.22 mm behind the male gonopore and at 2.5 mm distant from the anterior margin, measuring 0.22 mm (Figure 2H, 3A).

Male reproductive system: Male copulatory apparatus located posterior to male pore and slightly diagonal. The well-developed muscularised seminal vesicle is oval, measuring 0.309 mm x 0.165 mm. Prostatic vesicle arranged ventral to the seminal vesicle, oval, measures 0.25 mm x 0.12 mm. The prostatic vesicle opens into the penis through short prostatic duct whereas the seminal vesicle empties into the penis via comparatively long and curved ejaculatory duct (Figure 3D, E). Pointed, armed penis (143.17μm) enters narrow and semi-circular male atrium (373.11μm) (Figure 3D).

Female reproductive system: Female atrium oval (83.20 μm wide) and opens into the vagina with shallow invagination (33.06 μm) of cement pouch. The cement glands visible through the ventral surface and densely arrange (Figure 2H, 3A, 3E). Uteri visible through the ventral surface (Figure 2H, 3A) and connect with the vagina (164.09 μm) (Figure 3E).

Taxonomic Remarks: Three species namely Cycloporus albofasciatus Newman & Canon, 2002, C. papillosus (Sars, 1878), and C. xanthopunctatus Newman & Canon, 2002 display papillate dorsal surface.

Cycloporus papillosus has an orange dorsal surface with red spots and greenish-red papillae (Sars 1878). Further, Lang (1884) and recently Noreña et al. (2014) extended the description of this species with greater details of the external morphological and reproductive characters. The species is mainly distinguished from the C. decoratus sp. nov. due to the ground, papillae and tentacles colour pattern, the shape of the pharynx, number of intestinal branches, number of cerebral and tentacular eyespot structure. Cycloporus xanthopunctatus have bright yellow spots on the dorsal surface. Furthermore, this Australian species owns 45 cerebral eyespots in each cluster and tentacular bumps display 25 eyespots, and these features sufficiently distinguishes it from the presently described new species.

In this species assemblage, the most resembling species is C. albofaciatus, named due to its distinct pattern of white transverse streaks. Apart from this aforesaid character, C. albofaciatus and C. decoratus sp. nov. possess number of cerebral eyespots in a similar range. However, there are marked differences between the two species. Cycloporus albofaciatus has irregular spots, dots and transverse opaque white blotches that are absent in the newly described species. Instead, C. decoratus sp. nov. has rounded black dots over the dorsal. The former has scattered tentacular eyespots ranging from 15–20 each side whereas the number of eyespots lying over the tentacles of the newly described species is more than the double.

Presently, star- or cross-like pattern formed by white streaks markedly distinguishes this species from C. albofaciatus. To precisely comprehend this pattern, the images of the specimen deposited by Dr. Newman in the Queensland Museum (FW222/HC1955 WM, collected: 31-03-94 from Dam awan, Madang, PNG, Size: 7 x 4mm) were obtained. The comparative examination of these images emphasized the distinctive dorsal colour pattern of newly described Indian species from C. albofaciatus (Figure 3B, C). Currently, details of the male and female apparatus of C. albofaciatus are not available to complement the present comparative review.

Following the 2014 collection, no specimens were observed until 2018 at any of these sites mentioned.