Lithacrosiphon cristatus lakshadweepensis Haldar, 1991
The description of this subspecies was based on five specimens collected off western India. It differs from the nominate form in two aspects: number of grooves in the anal shield, 20-25 vs. 30-50, and number of longitudinal muscle bands, 8-15 vs. 13-24. The disjunct distribution supports the subspecific designation.
(From Haldar, 1991)
This subspecies is similar to the nominotypical species, but readily differs from it in number of grooves on the anal shield, 30-50 (vs. 20-25), and number of LMBs, 13-24 (vs. 8-15), and in the geographical distribution (see L. cristatus cristatus species page).
(From Haldar, 1991)
External anatomy
Introvert about half as long as trunk.
Tentacular crown with no more than 10 tentacles.
Distal bidentate hooks are arranged in 14-19 rings and measure 4µm in height and width at the base. Scattered unidentate hooks, with 5µm height and 4µm width at the base, are immediately posterior to the bidentate hooks. Pyramidal hooks, with 4-5µm heights, are scattered on the proximal region of the introvert, behind the unidentate hooks.
The anal shield, 1.7-3.9 mm in height, is calcareous and cone shaped, with round apex, and 20-25 longitudinal grooves.
The trunk, 14-21 mm in length and 6-8 mm in width, is thin in the mid-trunk but thicker and opaque at the anterior and posterior region.
The caudal shield is absent.
Internal anatomy
The longitudinal muscle layer of the trunk wall is divided into 8-15 anastomosing bands.
The spindle muscle is attached at both ends.
A pair of retractor muscles originates about one-seventh of the trunk length from the posterior extremity.
This subspecies has been found only in shallow water in the Arabian Sea off western India in coral rubble (Cutler, 1994).
This species inhabits coral rubble (Cutler, 1994).