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A survey of the tail spine characteristics of stingrays frequenting Indo-Pacific ocean areas between the International Date Line and the Chagos Archipelago-Maldive Islands

Tail spines characteristics were examined of 66 species of stingrays (545 males, 619 females) (Order Myliobatiformes) frequenting Indo-Pacific area between the International Date Line and the Chagos Archipelago-Maldive Islands. Serrated tail spines were absent on: Aetomylaeus nichofi, A. vespertilio, Urogymnus asperrimus, Gymnura australis, Gymnura poeecilara, Mania birostris, Mobula. thurstoni. Tail spines were missing for Himantura pareh (type in British Museum), and H. oxyrhyncha (type in Paris Museum) while H. pastinacoides (type in British Museum) had the tail Cut Off. H. undulata, a wide ranging species in the Indo-Pacific, H. fluviatilis of the Ganges River, as well as newly described Himantura kittipongi of Thailand, Himantura horteli from Indonesia, Pastinachus solocirostris from the Indo-Malay Archipelago, and Himantura bolistoma from Borneo were not available for study. Spine serration totals did not follow a primitive to advanced genera relationship of. Plesiobatis, Hexatrygon, Urobatis, Urotrygon, Trygonoptera, Urolophus, Dasyatis, Himantura, Pastinachus, Pteroplalytrygon, Taeniura, Aetoplatea, Gymnura, Aetobalus, Myliobatis, Himantura, Rhinoptera, Manta and Mobula. Total tail serrations were highly variable. Dasyatid species had the widest range of serrations, Urolophid species the least. A statistical correlation existed between genera total tail spine or serrations total tail spine serrations and type of swimmers or habitat frequented. Tail serrations above 100 were of active ocean swimmers; species with 70-100 total serrations were mid-water swimmers; species with 50-70 spine serrations were usually benthic forms as well as stingrays with 25-50 spine serrations were usually benthic forms that often entered freshwaters. Spine serrations of freshwater inhabiting species varied wildly from I 10 (Pastinachus sephen) to 23 (Dasyatis laosensis). Likewise, species size and size of its serrated spine and total serrations was not correlated; for example: Dasyatis brevicaudatus, (a 2.1 cm disk width species), may have 261 spine serrations while Aetobatis narinari (a 3 m DW species) may have only 55 spine serrations. Smaller species likewise could be large or small and have more or less total spine serrations, for example, Taeniura meyeni, (a 180 cm DW species) has 84 total spine serrations vs. Dasyatis bennetti, (a 30 cm, DW species) had 84-100 total serrations. Prebase lengths as well as percent groove lengths varied widely between genera and species. Confusion still persists pertaining to the proper generic designation for many stingrays. However, stingray tail spine characteristics are useful in distinguishing species, identity, and the species causing injuries.

Authors

Schwatrz F .

Year

1

ISBN-13

0

Keywords

stingrays, stingrays, tail spine serrations, Africa, Arabia

Link

http://dc.lib.unc.edu/cdm/singleitem/collection/jncas/id/3999/rec/2