Polycarpa reniformis (Sluiter, 1904)

Mondal, Jhimli & Raghunathan, C., 2022, Addition of three Ascidian species to Indian waters from Andaman and Nicobar Islands, Records of the Zoological Survey of India 122 (3), pp. 275-282 : 276-278

1. Polycarpa reniformis (Sluiter, 1904)

Material examined: 1 ex.: India, Andaman and Nicobar Islands, District South Andaman, Rutland Island , 11°25.112’N; 92°36.535’E, Depth : 7 m, 16.xii. 2016, Coll.: Jhimli Mondal (Reg. No.: ZSI/ ANRC – 16552) .

Description: The specimen is 3.5 cm long, and elongated in shape ( Figure 2a ). The tunic is thick, opaque, cartilaginous, soft and brownish. The test surface is with wrinkles and epibionts. The branchial aperture is terminal; both the apertures are very inconspicuous. Apertures are having four lobes on each of them.

Strong muscles are present on the body wall and form a mesh originating from each of the siphons. The prepharyngeal band is narrow. Branchial tentacles are about 100 in number. The dorsal tubercle has an inverted S-shaped opening of the neural gland ( Figure 2b ). The branchial sac is with four folds on each side of the body ( Figure 2c ) and 8-10 stigmata are present per mesh ( Figure 2d ).

Branchial formula: DL 2 (9) 2 (12) 2 (11) 1 (12) 1 E (left side)

Gut forms a loop ( Figure 2e ). The stomach is with 20 longitudinal folds internally. The anal border is with 11 irregular lobes ( Figure 2e ). A single large endocarp is enclosed in the gut loop, no endocarp is found on the body wall. Gonads are spindle-shaped, upright attached to the body wall by a very small ligament at the proximal side of the body as stated by Kott (1985). The rest of the part is free from the body wall ( Figure 2f ). 24 gonads are found on the right side of the body and 27 on the left side ( Figure 2e ). Testes are bi or trilobed and arranged in two rows.

Remarks: The species was first reported by Sluiter in 1904 from Indonesia; however, the report on the particular species is scanty. After Sluiter, Kott (1985) reported the species from Australia. Before Kott, one more report has been found from Australia by Hartmeyer and Michelsen, but Kott expresses her doubt that the species found by Hartmeyer and Michelsen is the same as the species found by Kott. Later on, Lee et al., (2016) unveil the distribution of present species from Taiwan, which Su recorded in 2013 ( Lee et al., 2016).

The present species has been identified by its characteristic feature, i.e., delicate body wall, complete opening of a neural gland on the tubercle, single endocarp, and presence of numerous upright gonads on the body wall as stated by Kott (1985).

Distribution: India: Andaman and Nicobar Islands ( Figure 1 ); Elsewhere: Australia, and Indonesia ( Kott, 1985), Taiwan ( Lee et al., 2016).

Figures

Figure 1. Study areas of Andaman and Nicobar Islands.

Figure 2. Polycarpa reniformis (Sluiter, 1904): a. Preserved specimen. b. Dorsal tubercle. c. Branchial sac with branchial folds. d. Stigmata. e. Gut loop on the left side of the body along with gonads. f. Gonads. (Abbreviation: DL: Dorsal Lamina, DT: Dorsal Tubercle, E: Endostyle, EC: Endocarp, G: Gonad, GL: Gut loop, ST: Stigmata, each number is denoting each branchial fold), (Scale: b– 1mm, 28.4x; c– 2mm, 11x; d– 500μm, 37.2x; e– 5mm, 7.80x; f– 1mm, 28x).