Umbra limi

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 : 13-17

Umbra limi - Central Mudminnow

Neotype (Fig. 6)

NYSM 56455 , adult, 58.8 mm SL, Bull Creek, an upland tributary to Yellow Creek, upstream of Pine Lake, south of Poland , Mahoning County, Ohio, 1 April 2004, R.A. Daniels, R.E. Schmidt, T.O. Matson .

Paratopotypes

NYSM 56456 , adults, 16 specimens taken with neotype , 46.4-58.3 mm SL .

Paratypes

NYSM 1309 , adults, 2 specimens, 62.0-67.9 mm SL, Lake Champlain, at Burlington , Chittenden County, Vermont, 1853, Z. Thompson .

Diagnosis

Umbra limi is closely related to Umbra pygmaea in the family Umbridae ( López et al. 2000). Umbra limi tends to have a snout that is longer than its eye diameter and its caudal peduncle depth is usually less than 60% body depth. The color pattern of U. limi has dark, vertical bars interspersed by lighter areas. There are usually more than 12 bars on each side. It differs from U. krameri , which lacks a prominent vertical black bar at the end of the caudal peduncle and has a mandibular lateral line with two pores (absent in U. limi , Nelson 1972). It differs from U. pygmaea in color pattern and usually in the relative length of its snout.

Description

The similarities between U. limi and U. pygmaea are more striking than their differences. Umbra limi also is a robust, compact fish, body terete forward, tapering to slab-sidedness in the caudal peduncle region. Dorsal profile is slightly arched and the ventral profile is almost flat. Deepest part of the body is just anterior to the dorsal-fin origin, at about 23% SL (Table 5). Caudal peduncle depth is about 13% SL, so there is little change in the body profile from the posterior part of the head to the end of the caudal peduncle. Caudal peduncle is longer than deep. Dorsal fin origin is about 60% SL, anal fin origin about 70% SL, but both fins are coterminal. Caudal fin is rounded. Pectoral fins are thoracic and ventral; pelvic fins are abdominal and ventral. The body is entirely scaled, with modified scales encroaching onto the caudal rays.

The head is about 30% SL. The postorbital length is slightly greater than 50% HL. The snout, at 23% HL, is blunt, relatively short, and usually its length is greater than the orbit diameter. Interorbital distance is also greater than orbit diameter. General shape of the head is conical, with greatest depth posterior, tapering to snout. Eyes are dorsal. Mouth is terminal, horizontal and non-protractile. There are teeth on the premaxillary, dentary, vomer and palatine. Paired nostrils are on the snout anterior to the eyes, each with simple incurrent and excurrent openings. Head is scaled; only the chin, anterior part of the snout, and gular and branchiostegal areas are free of scales. Cephalic lateral line system comprises supraorbital, infraorbital, temporal and preopercular canals, and is identical to that found in U. pygmaea . Operculum is rounded, relatively large, and has a flap of skin along its entire margin. Preoperculum is also rounded and is free only at its angle. The four or five branchiostegal rays are short and thick. Gill membranes are free from the isthmus.

Fins are similar to those of U. pygmaea . Caudal fin is rounded and symmetrical; with 16-20 total rays, 9-11 branched; ventral and dorsal procurrent rays present. The dorsal fin with 13-16 rays, is progressive, although the posteriormost rays are definitely shorter that those immediately anterior. Anal fin with 9-11 rays; the longest rays are those in the middle. Pectoral fin insertion just posterior to angle of operculum, base small, oblique. Fin rounded, slightly asymmetrical, with 13-16 rays. Middle rays longest. Pelvic fin insertion just anterior to dorsal-fin origin. Six pelvic rays present, middle rays longest.

Scales are very similar to those of U. pygmaea (Daniels 1996). Lateral series count ranges from 31-36 scales. There are 12-13 transverse scale rows.

Dorsum dark brown or black, venter lighter ranging from cream to light brown. There are several (usually more than 12) dark, vertical dark bars that run the length of the body, each is separated by a lighter area. On some specimens, these bars can be indistinct. There is a prominent vertical dark bar at the distal edge of the caudal peduncle. Head is dark; operculum is heavily pigmented; cheek ranges from as dark as the operculum to much lighter. The opercular flap is lightly pigmented. The proximal edge of the caudal fin is also heavily pigmented. Fins can have a weak red tint. Breeding fish can be very dark with indistinct bars; venter is pink, body with iridescent greens and dark pink areas scattered among the dark pigment.

Comparison to original description

Kirtland (1840) described the Central Mudminnow as Hydrargira limi from specimens found in the headwaters of Yellow Creek, Village of Poland, Trumbull County, Ohio. There is no doubt that he described the species recognized today as Umbra limi . The description, although brief, is accurate. The original figure (Fig. 7), drawn by Kirtland, is housed at the Bowdoin College library (Moulton 1957).

Etymology

Jared Potter Kirtland was a neophyte ichthyologist when he described Umbra limi (Kirtland 1840) and relied heavily on D. Humphreys Storer for guidance and support (Dexter 1980). His descriptions are generally accurate and as thorough as was customary at the time. By placing this mudminnow into the genus Hydrargira Lacepède 1803, Kirtland signaled that he believed that this species was closely related to, or was, a killifish. Although there is a typographical error in the presentation of the name, spelled Hydargira in the text, it is correctly spelled under the figure. Placing mudminnows in this genus, under Cyprinidae , was customary at the time. DeKay (1842) described Hydrargira atricauda (with a typographical error in the presentation of the specific name), the Champlain Minnow, and Thompson (1842) described Hydrargyra fusca , also from Lake Champlain. It is curious that DeKay did not recognize a relationship between the Eastern and Central Mudminnow despite their extreme morphological and meristic similarity. Kirtland (1840) noted that the specimens were taken in mud, so the specific name is likely the genitive of the Latin noun limus, translated as slime, mud, or mire.