7949

• UCREFRP Catalog Number: 7949
• Author: Williams, J. E.
• Title: Taxonomic Status Of
• USFW Year: 1978
• Copyright Material: YES

DISCUSSION. Rhinichthys osculus moapae is characterized by
adaptations to s'wift water. Large, expansive, falcate dorsal and anal
fins and expansive, deeply-forked caudals are typical. The caudal
peduncle is relatively long and slender. ;\iIany of these swift-water
adaptations are illustrated by comparing a spring form of Rhinichthys
05culus (for example, the population of R. o. robustus inhabiting the
Big Shipley Spring, Diamond Valley, Eureka County, Nevada) to
R. o. moapae (Table 1). Rhinichthys osculus moapae exhibits larger
size, more slender head, body, and caudal peduncle, greater anal to
caudal length, and greater dorsal and caudal fln lengths. Complete re-
sults of morphometric and meristic analyses are reported in Tables
2. and 3.
In addition to the information provided in the tables, the presence
or absence of barbels and premaxillary frenum was recorded. Of 32-
fish examined for these characters, 90.6% had 2. barbels and 93.8%
had a premaxillary frenum, which often is well developed. No fish
vvere found with only 1 barbel. All fish with barbels also possessed a
premaxillary frenum and only 1 fish without barbels possessed a pre-
maxillary frenum. Pelvic fins were absent in 4.1 % of 74 fish examined.

RELATIONSHIPS AND DIAGNOSIS. Hubbs (1943) interpreted
a subspecies as any genetic form which shows reasonable geographical
or ecological consistency, and which can usually be distinguished on
its totality of characters. By these criteria, R. o. moapae, with its nu-

TABLE 1

l'dorphometric comparison of Rhinichthys osculus moapae with R. o. robustus from
Big Shipley Spring, Diamond Valley, Nevada. lWean (in parentheses)
and range are given.

R. o. rolJustus*

R. o. moapae

Standard length (mm)
Head deptht
Predorsallength
Anal to caudal length
Greatest body depth
Caudal peduncle depth
Depressed dorsal fin length
Caudal fin length

31-37 (34)
185-218(198)
558-623(591)
303-354(330)
247-283(263)
127-154(136)
208-243(224)
246-292(259)

42-77 (53)
129-166(146)
481-575(510)
323-483(394)
183-253(214)
91-126(109)
223-298(258)
229-305 (271)

- DilLa from Hubbs ct aJ. (1974).
";- :\I(~asurements in thousandths of standa.rd length.

514