World Status, Exploitation and Trade - WIDECAST

..INTRODUCTIONshown to deserve formal recognition as C. m. viridis (Schneider, 1783). Allthese four subspecific names were originally first employed as specificepithetsThe strikingly dark. Gulf of California population was formally described asa discrete subspecies C. m. carrinegra by Caldwell in 1962, but again, thisname has not been widely used, and the differences between carrinegra andagassizii (the latter taxon founded on turtles from the Pacific coast ofGuatemala) have not been explored or defined. Many, such as Clifftonet al. . (1982), Pritchard (1979), Pritchard and Trebbau (1984), appear touse the latter name for all coastal Pacific populations (including theGalapagos)Pritchard (1979:684) noted that the only group of populations whosedifferentiation as a distinct subspecies has been universally accepted isthe East Pacific C. m. agassizii (contrary to Carr (1975), Pritchard doesnot include Hawaii and the Marshall Islands in the range of this taxon).Turtles nesting along the East Pacific mainland, and to a lesser degreethose in the Galapagos, do indeed differ from other forms of mydas in size,colour and carapace shape. Pritchard (1983: 110) also noted occasionalapparent sympatry between agassizi i and mydas forms, and cites this asevidence for species-level differentiation of agassizi i . Whether such casessimply represent the chance encounter of individuals from relativelydistinct populations in what is primarily a foraging area for one or bothindividuals, or actual failure to interbreed given that both are in thephysiological condition to do so, has not been determined.Although Bocourt originally described agassizii as a full species back in1868, this usage has never gained general acceptance, particularly in thepresent century (when the systematic practices of the last century are oftenregarded as cavalier and unsophisticated). However, there has been agrowing tendency in recent years for this population again to be treated ashaving specific rank, as C. agassizii (East Pacific or Black Turtle). Thismay well be justified; the morphological differences of these turtles maywell be based on reproductive isolation, but there has never been athorough, published discussion of this matter, with a formal taxonomicre-description, set in the context of the overall systematics of theC. mydas group.Curiously, results of one of the first, and still one of the very few,attempts to use biochemical indicators of genetic diversity in sea turtles(an analysis of the amino acid composition of shell keratins) suggested adifferent conclusion. Hendrickson (1979:24) found the Gulf of Californiapopulation ( viz . C. m. carrinegra Caldwell, 1962) to be "by far the mostdistinctive" of the eight geographic groups studied, which included "true"agassizii from Oaxaca in Mexico. It was the only form showing "multiplediagnostic differences from all other populations". Further, "This strikingamount of differentiation constitutes strong support for the observedmorphological and physiological differences between this population and therest of the green turtles." Hendrickson later (1980:601) stated thatC. m. carrinegra Caldwell should be elevated to full species status; itshould be noted that Hendrickson explicitly (in 1979 at least) uses thisname for the Gulf of California population. In other words, this is not acase for the use of agassizi i at species level for all Pacific American"green turtles", and Pritchard (1983) was incorrect in stating thatHendrickson (1980) had presented persuasive arguments for the recognition ofC. agassizii - the argument was for carrinegra .