Semibalanus sinnurensis   Daniel,  1962 (Barnacle)
Organism information awaits expert curation
Class: Maxillopoda

Size: Carino-rostral diameter 5 mm, height 2.5 mm

Color: Parietes dark brown, radii brownish - white, alae white, sheath a duller shade of the external color. Entire shell covered by a persistent brown epidermis.

Greatly depressed, with a large rhomboidal orifice and circular basis. Walls of the shell thick, with the compartments weakly united and held in position firmly by the persistent epidermis. Parietes porous, the pores arranged regularly in a single row, narrow at the top and broad at the base; pores at the centre of each compartment more angular and larger than those at the ends. Longitudinal septa between the pores wider at the base and narrow near the sheath and denticulate on both sides. Parietes provided externally with minute calcareous projections below the epicuticle; inner faces smooth, with irregular anastomosing wrinkles near the base. Radii rather wide without any pores, also smooth, sheath long. Compartments almost of the same height, the rostrum not prolonged downwards below the other compartments, basis membranous.
Opercular valves sunken well below the peritreme. Scutum rather flat; tergal margin slightly deflected occludent margin smooth, without teeth. Externally with low and faint growth ridges almost smooth towards the basal margin. Internally, articular ridge thin, length three-fourths tergal margin. Adductor ridge short but strong and distinct. Pit for depressor muscle small, continued as furrow to articular ridge. Tergum delicately ridged on the external surface, groove to the spur closed, with a beak at the apex. Scutal margin inwardly refluxed near apex. Carinal margin arched considerably before meeting the scutum margin. Spur moderately long and pointed at the basal tip, separated by its own width from the basiscutal angle. Basal margin with a depression before meeting the carinal margin. Articular ridge and reflection of the scutal ridge both high and acute.
Mouth Parts: Labrum with two or three teeth on either side of the central notch. Maxilla with the lower half of the free edge highly protuberant. Two long straight spines borne on the protuberance, with two short fine spines in the middle below the two long and curved upper spines. Apical tip with a pair of setae. Lower margin fringed with slender hairs. Maxilla oval, both the lobes well developed with long hairs on the inner margin and distally. Numerous stout hairs occupy the outer margin. Mandible with five teeth, the fourth being double toothed. Lower angle bears two pointed cusps. Cutting edge between the third and fourth teeth and the fourth and fifth teeth bears a number of fine spines. Ventral margin with a row of fine spines and the surface of the appendage bears a number of short hairs.
Cirri: Cirri I, II and III with unequal rami. Posterior ramus of cirrus I short and wide and bears long and thin setae. Anterior ramus slender and clothed with numerous long setae, terminal article of anterior ramus bears three stout setae. Cirrus II with the posterior ramus slightly longer than the anterior. Both the rami have protuberant margins from the fifth segment onwards, and the first and second segments have indistinct sutures and not clearly differentiated. Cirrus III with the posterior ramus slightly shorter than the anterior; both the rami profusely bristled with long slender setae. Cirri IV, V and VI with equal rami. Each segment of cirri IV to VI with a pair each of very long setae, moderately long setae and of short and stout setae; at the posterior distal angle, each segment bears three long setae.

Synonym (s)

Common Name (s)
Economic Importance and Threats

Habitat:  Sandy, Coastal


• Tamil Nadu, Parangipettai INDIA (Record: 2006)

Literature Source(s)
  • Fernando, SA (2006) Monograph on Indian Barnacles Ocean science and technology Cell, Kochi 9-199 Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -

Page last updated on:2012-05-22

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