Striatobalanus tenuis (Hoek, 1883) Figures 2A-C, 4

Examined material.

four specimens (BD: 9.43-13.59 mm), LFSc.ZRC-157 (2 specimens on Murex ternispina Lamarck, 1822, one specimen on Babylonia spirata Linnaeus, 1758, and one specimen on Bufonaria echinata Link, 1807), Jakhau, Kachchh (23°11.30'N, 68°37.35'E), 9 January 2020, Gujarat, India, sandy shore, leg. M. Doshi.

Diagnosis

(modified from Chan et al. 2009). Shell composed of six plates, conical, white, orifice deeply toothed (Fig. 2B). Scutum triangular, strongly sculptured on dorsal surface (Fig. 2C). Tergum triangular with long and narrow spur, scutal margin concave, medial furrow present on dorsal side of tergum (Fig. 2C). Scutal and tergal outer surfaces striated longitudinally. Maxilla triangular, covered with dense setae (Fig. 4A). Maxillule not notched, with two large setae on upper region (Fig. 4B). Mandible with five teeth excluding inferior angle, inferior angle blunt, 2nd and 3rd teeth bi-dentate (Fig. 4C-E). Mandibulatory palp rounded with setae at tip and superior margin (Fig. 4F). Labrum bullate shaped with distinct and deep notch having two prominent teeth on each side of cutting edge (Fig. 4G, H).

Remarks.

The specimens examined in the present study agree with the description given by Chan (2009) and Chan et al. (2009). Striatobalanus tenuis closely resembles S. amaryllis (Darwin, 1854), but differs from the latter in the following characters: mandible with five equally spaced teeth (in S. amaryllis, the mandible has four teeth and the distance between the 3rd and 4th teeth is larger than the rest, Chan 2009); tergum triangular with short and wide spur (tergum narrow with beak produced apically in S. amaryllis, Chan 2009); and maxilla triangular, covered with dense setae (maxilla bilobed, elongated with dense setae on inferior margins in S. amaryllis, Chan 2009).

Striatobalanus tenuis also differs from S. krugeri (Pilsbry, 1916) and S. taiwanensis (Hiro, 1939) in that it has a median furrow on its tergum.

Worldwide distribution.

This species has been reported from South Africa, East China Sea, South China Sea, Japan, the Philippines, Indonesia (Chan 2009), Vietnam (Poltarukha 2010) and India (Krishnamoorthy 2007).

Distribution in India.

This species has been reported from Gujarat (present study), Tamil Nadu (Krishnamoorthy 2007; Daniel 1956), Odisha (formerly Orissa) (Nilsson-Cantell 1938), and Karnataka (Nilsson-Cantell 1938).