Orconectes palmeri longimanus

Johnson, Daniel P., 2010, Four new crayfishes (Decapoda: Cambaridae) of the genus Orconectes from Texas, Zootaxa 2626, pp. 1-45 : 2-3

Notes on Orconectes palmeri longimanus

The first known collection of O. p. longimanus at the type locality (Red River near Arthur City, Lamar County, Texas), was made sometime prior to its description in 1898 ( Faxon, 1898). It was again collected in

1. Now considered O. maletae

2. This specimen almost certainly is O. texanus , described herein the area in 1951 (USNM 133183). Up until this point of time, no other Orconectes species were reported from the locality. Between 2000 and 2002, Sterling K. and Nathan K. Johnson (pers. comm.), collected the taxon together with what they identified as O. difficilis (described as O. cyanodigitus herein) near the locality. They also found O. p. longimanus in the Red River drainage (not including the Sulphur River) in Red River and Fannin counties, which are adjacent to Lamar county. In 2007 and 2008 the author collected O. cyanodigitus at seven sites along a 160 km stretch of the Red River and its tributaries in Lamar, Red River and Bowie Counties, Texas and Little River County, Arkansas, including 94 specimens within 3 km of the O. p. longimanus type locality; but failed to find O. p. longimanus . From this evidence, it is apparent that O. p. longimanus has been extirpated from its type locality (or is on the verge thereof), and likely as a result of O. cyanodigitus displacing it. This displacement may be the result of environmental changes, with O. cyanodigitus previously occurring in much lower numbers or more restricted in range within the Red River system. The species may have alternatively been introduced from another watershed. If this is the case, the Canadian River system would be the most likely source, given that the two most closely related species, O. deanae and O. difficilis , occur in that watershed.

For comparative analysis with O. p. longimanus , a large number of specimens collected in the Sulphur River basin, a tributary of the Red River, was used. It would have been preferable to compare specimens from the type locality, but the only known form I male specimens are that of the very small 1898 type series (2 males), which were not borrowed due to their presumed value. Photographs of specimens collected near the type locality ( Johnson and Johnson, 2008) and from the Sulphur River show essentially identical color patterns. That, along with the close proximity to the type locality (as small as 60 km) and the Sulphur River being a tributary of the Red River, indicates they are likely the same crayfish and use of the Sulphur River collections for comparative analysis is reasonable.