Umbra

Robert E. Schmidt & Robert A. Daniels, 2006, Hybridization in Umbridae in the Hudson River, New York, with Designation of Neotypes for Umbra limi and Umbra pygmaea., Zootaxa 1113, pp. 1-20 : 1-3

[[ Genus Umbra ]]

There are two species of Umbridae in the Eastern United States (Lee et al. 1980 et seq.): the Central Mudminnow ( Umbra limi ) and the Eastern Mudminnow ( U. pygmaea ). Phylogenetic analyses indicate that these two species are sister taxa (Cavender 1969, Kettler et al. 1986, López et al. 2000, López et al. 2004, Nelson 1972, Wilson and Veilleux 1982). Recently, we received a mudminnow collection from Manitou Marsh, a fresh to brackish tidal marsh in Putnam County, New York (Fig. 1). A subsequent collection (1998) of mudminnow from a supratidal pool in Manitou Marsh contained individuals that were not easily classified as either species. Geographic distinctions are no longer possible in the Hudson River Valley, and the specimens collected in Manitou Marsh (New York State Museum -NYSM 55623) had color patterns not readily classified as either striped or blotched. Smith (1985) provided a table of meristics and morphometrics for both mudminnows and, although he only examined five specimens of each species, identified several differences between them. The purposes of this paper are to present evidence of hybridization between these two species of mudminnow in nature and to designate neotypes for Umbra limi and Umbra pygmaea .

Umbra pygmaea is native to the Hudson River drainage, New York, and the type locality is the Sparkill, a Hudson River tributary (DeKay 1842). Lee et al. (1980 et seq) showed that the ranges of U. pygmaea and U. limi did not overlap in New York State and that U. limi was absent from the Hudson River drainage but was present to the north in the Lake Champlain watershed and to the west in the Oswego River watershed. Smith (1985) documented U. limi from the tidal Hudson River and its major tributary, the Mohawk River. We have specimens of U. limi from the Hudson River in 1976 (NYSM 1310, 11672). Umbra limi may have extended its range into the Hudson River from the north through the Champlain Canal or from the west through the Erie Canal sometime since the 1890s when the number of locks was reduced, the locks were enlarged, and the river channel was used for ship traffic (Daniels 2001). Alternatively, they may have been directly introduced into the Hudson watershed.

Although isolated specimens of U. limi have been collected from the tidal Hudson River well south of the northern extent of the salt front, their preferred habitat appears to be in supratidal pools in fresh tidal marshes, a habitat that is rare and rarely sampled. Erik Kiviat (Hudsonia Ltd., pers. comm.) collected specimens in 1973 from a Hudson River supratidal pool. Beebe and Savidge (1988) listed both Umbra species from the tidal Hudson River but examination of four of their specimens (NYSM 14350, 14367, 14490) indicated that U. pygmaea was probably misidentified. Thus far, no verified records of U. pygmaea exist for the tidal Hudson River, and the species is limited to tributaries west of the estuary: Wallkill River, Moodna Creek, and Sparkill Creek (Smith 1985).

All authors of regional or national identification manuals who were required to distinguish between U. pygmaea and U. limi , did so by geography or color pattern (Cooper 1983, Eddy 1969, Moore 1968, Page and Burr 1991, Smith 1985, Werner 2004). Umbra pygmaea is usually described as striped whereas U. limi has vertical bars or blotches.