Triviinae
Figured below are a series of images of Triviinae, a subfamily of Triviidae. Aside from the distinctive Trivia (Trivirostra) exigua, identifications of all others are kept on hold as the relationships and distinctions between species is still confusing.
In Liltved's Cowries and their Relatives of Southern Africa (1st edition), his discussion on Trivia oryza notes that it is closely relationed to Trivia pellucidula. And he suggests further anatomical examination may prove they make up one highly variable species. Similar remarks are made under his discussion on Trivia hordacea, noting external similarities of living Trivia hordacea, pellucidula and oryza. It is probable that all exist on Guam, and perhaps a few others. Identifying a species by conchological features alone is difficult and using external anatomical features, when possible, may help.
Trivia (Trivirostra) exigua (Gray, 1831)
L x W x H: 4.5 x 3.2 x 2.8mm. Under coral rubble. 60 ft. Two Lover's Point, Guam (just north of the Tumon Bay Preserve boundary marker). Collected by Bob Abela on 14 May 2006. The mantle was clear with blunt yellow papillae. (Unfortunately, the animal died before I had an opportunity to photograph it.)
Trivia specimen 248
L x W x H: 6.1 x 4.3 x 3.7mm. Under coral rubble with a heavy growth of algae. 62 ft. Orote Cliffs, Guam. Collected by Bob Abela on 30 January 2005. No dorsal sulcas (or very inconspicuous).
Trivia specimen 280
L x W x H: 4.8 x 3.4 x 3.0mm. Under coral rubble. 53 ft. Agana Bay, Guam. Collected by Bob Abela on 22 June 2005.
Trivia specimen 266
L x W x H: 6.5 x 5.0 x 4.1mm. On the reef flat, on top of coral rubble covered with a heavy growth of brown algae. Approximately 5 ft. Tanguissan Beach, Guam. Collected by Bob Abela on 12 May 2005.
Trivia specimen 267
L x W x H: 7.6 x 5.2 x 4.2mm. Same collecting information as Specimen 266. Although the mantle coloration and pattern is different, it is very likely the same species. They were just a few feet apart from each other. This specimen is subadult and its dorsum has a slight scar.
Trivia specimen 268
L x W x H: 8.4 x 5.9 x 5.1mm. On the reef flat, under coral rubble, less than 5 ft of water. Adelupe Point, Guam. Collected by Bob Abela on 19 May 2005.
Trivia specimen 269
L x W x H: 8.2 x 5.8 x 5.2 mm. Same species and collecting information as Specimen 268.
Trivia specimen 274
L x W x H: 6.9 x 5.1 x 4.4mm. Reef flats, less than 2 ft, under coral rubble. Alupang Cove, Asan Bay, Guam. Collected by Bob Abela on 04 June 2005. Appears to be the same species as specimens 268 and 269.
Trivia specimen 276
L x W x H: 5.7 x 4.1 x 3.6mm. Underside of rocks along perimeter of a pit just beyond the reef drop. 22 ft. Tanguissan Beach, Guam. Collected by Bob Abela on 05 June 2005. The animal died before photographing; however, the mantle was light tan with more faint, light tan blotches. The upper edge of the mantle had a very thin black outline. The foot was similar in color though pattern was not noted.
Trivia specimen 277
L x W x H: 5.4 x 4.0 x 3.5mm. Found underneath rubble under rubble along sand channel, 32 ft. Agana Bay, Guam. Collected by Bob Abela on 16 June 2005.
Trivia specimen 279
L x W x H: 4.5 x 3.0 x 2.6mm. Underside of rocks along perimeter of a pit just beyond the reef drop. 25 ft. Tanguissan Beach, Guam. Collected by Bob Abela on 21 June 2005.
References
Ernst, Trudi & Wesley Thorsson. 1999. Hawaii's Trivia. Internet Hawaiian Shell News, February 1999, Feature Section, pp 11-29.
Ernst, Trudi & Bill Ernst. 2000. Recent Finds: Trivia and Pusia Shell. Internet Hawaiian Shell News, March 2000, Month Section, pp. 8-10. (images & text pertaining to Trivia edgari)
Thorsson, Wesley. 2000. Some Recent Photographs of Mollusc Animals. Internet Hawaiian Shell News, May 2000, Month Section, pp. 10-11. (images & text pertaining to Trivia exigua)
Links
- Emmanuel Guillot de Suduiraut's Eurasia Shells
- Hardy's Internet Guide to Marine Gastropods - Triviinae
- OBIS Indo-Pacific Molluscan Database - family Triviidae | genus Trivia