Shell moderately thick and patelliform, of medium height. Apex positioned centrally or slightly anterior to center. All slopes straight to weakly convex. Exterior sculpture of numerous sharp radial ribs; weak secondary ribs intercalated between most primary ribs. Exterior of shell dirty white with vague yellow or reddish brown radial streaks. Central area of shell inside muscle scar opaque white. Intermediate area between the muscle scar and shell margin glossy orange-yellow to orange. Interior margin narrow, glossy white, reflecting exterior shell pattern.
Radula: Radula with three pairs of lateral teeth and two pairs of marginal teeth. First lateral teeth set close together on anterior edge of basal plates, with blunt cusp. Second lateral teeth directly posterior to first lateral teeth, with blunt cusp. Third lateral teeth almost the same width as second lateral teeth and also blunt. Two pairs of marginal teeth with spoon-like cusps.
Holotype dimensions: Length 12.7 mm, width 10.5 mm, height 5.7 mm.

The similar shell morphology of members of the Patelloida profunda group has caused many misidentifications at species level. Patelloida javanica n. sp. has been previously identified as Patelloida conoidalis of the Cook Island group (Cernohorsky, 1972) and Patelloida chamorrorum from Guam has been also misidentified as P. conoidalis. However, P. javanica n. sp. can be distinguished from both P. conoidalis and P. chamorrorum by its shell characters. Patelloida javanica n. sp. and P. conoidalis are similar, but with differences in the colour of their shells and in body size. Patelloida javanica n. sp. is dirty white with radial streaks, while P. conoidalis is white and completely lacks coloration. The intermediate area between the muscle scar and the shell margin of P. javanica n. sp. is glossy orange-yellow to orange, while that of P. conoidalis is glossy white. Patelloida javanica n. sp. is smaller than P. conoidalis (more than 2 cm in latter species). In turn, Patelloida chamorrorum is different from both P. javanica n. sp. and P. conoidalis in having dark rays or red markings. The interior margin of P. chamorrorum is white with dark markings corresponding to the exterior rays.
Additional distinctions come from a recent molecular phylogenetic study of this group. Kirkendale & Meyer (2004) compared mitochondrial 16S and COI partial gene sequences and their results also confirmed that P. javanica n. sp. from Java can be genetically distinguished from other species of the R profunda group.
The mtDNA results suggest that each major island archipelago contains an endemic lineage of the P. profunda group. With the exception of putative gene flow between the Philippines and Bali, each of the 13 major island groups tested harbours a distinct, reciprocally monophyletic lineage. Although Lindberg & Vermeij (1985) previously suggested that Java and New Guinea have the same Patelloida species, the population from New Guinea is likely to be different from that of Java, since a different species is distributed in Bali between Java and New Guinea, and each species of this group has a limited geographical distribution (Kirkendale & Meyer, 2004). Further work is needed to clarify the relationships between the population of Java and New Guinea.
In addition to the species listed by Christiaens (1975) and Lindberg & Vermeij (1985), Kirkendale & Meyer (2004) included Patelloida sp. (Zanzibar), Patelloida sp. (Sulawesi) and Patelloida sp. (Bali and Philippines). Further, an additional Patelloida sp. has been reported from Taiwan and from Yonaguni Island in southwestern Japan by Kosuge & Sasaki (2002). Further work will provide better understanding of the systematics of the R profunda group and their detailed geographic distribution.
According to Dharma (1988), six species of limpet have been reported in Indonesia. To these we add L. luchuana, C toreuma, C. sp. cf. orientalis and R sp. cf. striata. Lottia luchuana and C. toreuma are the first records in this area. The genus Lottia has its highest diversity in the Northern Pacific, and has been not reported from the central Indo-West Pacific region. This discovery is an important extension to the geographical distribution of Lottia. Patelloida sp. cf. striata tends to be smaller and thinner than Patelloida striata. This species does not occur on exposed rock surfaces, but on the back of rocks. Cellana sp. cf. orientalis is smaller than Cellana orientalis and tends to be less than 1 cm in length. This species can be found in the mid to high intertidal zone on limestone on sheltered shores. According to Powell (1973), Cellana orientalis has been classified into four subspecies, C. orientalis radiata Born, 1778, C radiata capensis (Gmelin, 1791), C. orientalis enneagona (Reeve, 1854) and C. orientalis orientalis (Pilsbry, 1891). Two subspecies, C. o. enneagona and C. o. orientalis are distributed in this island. Further, the Patelloida saccharina group is also a species complex (Kirkendale & Meyer, 2004; Sasaki, 1999). Patelloida saccarinoides from the Philippines has a flattened shell with 12 large radial ribs (Springsteen & Leobrera, 1986), and the population from Java tends to be higher in profile and with weak radial ribs. In Java, this species was also found living on oysters. It has a white color and small shell. It is difficult to clarify these species complexes using only morphological characters. Molecular techniques may resolve the taxonomic difficulties encountered in the convergent and highly variable shell morphologies found in limpets (Simison & Lindberg, 1999, 2003; Nakano & Ozawa, in press).

Type locality: Sedekan Beach, Java, Indonesia (06°52.9'S, 106°05'E).
Distribution: This species may be restricted to southwestern Java, since this is the only coastal outcrop of limestone in Java.
Habitat: This species occurs in crevices and hollows on vertical limestone rock faces on exposed shores in the high intertidal to supratidal zone. It does not occur in dense communi¬ties. This species appears to be a rare limpet in Java. We found one individual each at Pelabuan Ratu and Karang Hawu Beach, respectively, and 8 individuals at Sedekan Beach. Although this species was found separately from other limpets at Sedekan Beach, it co-occured with Scutellastra flexuosa (Quoy & Gaimard, 1834), Cellana orientalis radiata Born, 1778, Cellana orientalis enneagona (Reeve, 1854), Cellana toreuma (Reeve, 1854), Cellana testudinaria (Linnaeus, 1758), Lottia luchuana (Pilsbry, 1901), Patelloida saccharinoides Habe & Kosuge, 1996, Patelloida sp. cf. striata, and Cellana sp. cf. orientalis at Pelabuan Ratu and Karang Hawu Beach. This species may prefer shaded crevices , since there are more crevices and hollows in the limestone at Sedekan Beach than at Pelabuan Ratu or Karang Hawu Beach. However, other limpets may not live under such conditions. In Guam, only P. chamorrorum can also be found in the middle to high intertidal zone, where it occupies pits in the limestone. Cellana radiata and S. flexuosa inhabit wave-washed algal rocks at lower levels in Guam, There have been no detailed studies of the ecology of these tropical limpets.