Postanal Myomeres Research Articles

Effect of Temperature on the Identification of Larval Black Crappies, White Crappies, and F1 Hybrid Crappies

AbstractMyomere counts have been used to differentiate larval black crappies Pomoxis nigromaculatus and white crappies P. annularis; however, both hybridization and water temperatures during egg development can influence myomere numbers and thereby interfere with identification of larval crappies. We artificially produced pure black crappies, white crappies, and their F1 hybrids and allowed them to develop at different temperatures. We then compared counts of preanal, postanal, and total myomeres among taxa and water temperatures. Although white crappies had significantly more preanal myomeres and significantly fewer postanal myomeres than the black crappies or the F1 hybrids, counts of these myomeres overlapped too much to be useful for identification purposes. Some of the overlap of myomere numbers was caused by variation due to natal water temperature differences. Higher temperatures caused the anus to develop more posteriorly in larval crappie, influencing the number of preanal and postanal myomeres. Because myomere counts overlap so much and because hybridization and natal water temperature can induce variation in myomere numbers, myomere counts are not useful for discriminating between the two species of Pomoxis.

Ontogeny of Larval Greater Redhorse (Moxostoma valenciennesi)

Adult greater redhorse Moxostoma valenciennesi, were seined from the Grand River, Ontario, and artificially spawned in May 1997 and May 1998. Eggs hatched after 6–8 d at a mean temperature of 19 C. Eggs and larval development of 9–22-mm specimens are described. Ontogeny of larval greater redhorse was compared to that of other syntopic Moxostoma species from previously published studies, including river redhorse (M. carinatum), black redhorse (M. duquesnei), golden redhorse (M. erythrurum), shorthead redhorse (M. macrolepidotum), copper redhorse (M. hubbsi) and spotted sucker (Minytrema melanops). There was significant overlap between most meristic variables that were compared. However, the majority of greater redhorse (up to 18-mm) have myomere counts (27–33 pre-anal myomeres, 9–10 postanal myomeres and 39–42 total myomeres) that are different from other sympatric redhorse species and spotted suckers and may allow identification of greater redhorse as small as 9-mm.

Postembryonic development of the tubenose goby Proterorhinus marmoratus Pallas (Gobiidae) in the St. Clair River/Lake system, Ontario

Postembryonic developmental stages (5-40 mm) of the tubenose goby Proterorhinus marmoratus (PALLAS) are described and illustrated. Fish were collected in vegetated shore habitat in the St. Clair River/Lake system, Ontario, during 1994-2000. At hatch, the tubenose goby is precocious and closely resembles juveniles. Distinguishing morphologic characters include a cottid-like body with broad head, dorsolateral eyes, tubular anterior nostrils, two dorsal fins, thoracic fused pelvic fins, and spatulate caudal fin. Modal values for pre- and postanal myomeres are 11 and 20, respectively. The first dorsal fin has 6 spines, and the second dorsal fin has 16 soft rays. Anal, pectoral, pelvic fin spine and ray counts are I-13, 15, and I-5, respectively. Black stripes on snout, occiput, and anterior membranes of the first dorsal fin are distinguishing pigmentary features.

Morphology of Ruffe (Gymnocephalus cernuus) Protolarvae from the St. Louis River, Lake Superior

ABSTRACT We describe hatching and the morphological and meristic characteristics of 2.5–5.6 mm long ruffe protolarvae (Gymnocephalus cernuus). Eggs and sperm from St. Louis River ruffe were mixed, producing fertilized eggs that were 0.9–1.2 mm in diameter. Newly hatched protolarvae were 2.5–3.2 mm long. They had 14–15 preanal and 23–24 postanal myomeres, a continuous finfold of even width, unpigmented eyes, and a large anterior oil globule in the yolk sac, and the head deflected over the yolk sac. Pectoral fin buds appeared on the dorsal side of the yolk sac 5 hours after hatching. Two-day-old protolarvae had fully pigmented eyes, and the head was free from the yolk sac. Three-day-old protolarvae were 3.9–4.3 mm long and possessed opercula, gills, pectoral fins, and a functional jaw. Feeding and swimming began about one week after hatching when the yolk sac was almost completely absorbed. Protolarvae grew rapidly at 20–22°C and were 4.9–5.6 mm long after 13 days. Newly hatched ruffe protolarvae are distinguished from other Lake Superior percids by having the fewest preanal myomeres (14–15), the head deflected over the yolk sac, continuous finfold of even width, and a total length of less than 4.0 mm.

Larval identification of the ruffe, Gymnocephalus cernuus (Linnaeus) (Percidae: Percini), in the St. Louis River Estuary, Lake Superior drainage basin, Minnesota

A reproducing population of the Eurasian percid Gymnocephalus cernuus was discovered in the St. Louis River, Lake Superior basin, near Duluth, Minnesota. This study is the first documented evidence of the species occurrence and reproduction in North America. Larvae resemble typical percids and are described with emphasis on meristic, morphometric, and pigmentary characters. Ruffe are distinguished from all native North American percids by the presence of a slightly concave head becoming attenuated at larger length intervals, a pointed snout with teeth on the maxillary and premaxillary by the time a length of 11 mm is reached, a large dorsally pigmented swim bladder, a serrated preopercle, and few postanal myomeres (usually 18–22). In particular, ruffe superficially resemble johnny darters as yolk-sac larvae, and walleye, yellow perch, and logperch at lengths greater than 10 mm, but can be distinguished by the previously mentioned characteristics and a deep shoulder depth and a narrow caudal peduncle.

Description of Eggs, Larvae and Early Juveniles of the Stripetail Darter, Etheostoma kennicotti (Putnam) and Spottail Darter, E. squamiceps Jordan (Percidae: Etheostomatini) from Tributaries of the Ohio River

Specimens of larval to early juvenile Etheostoma kennicotti and E. squamiceps were comparatively examined using meristic, morphometric, and pigment characteristics. Ova diameters of E. kennicotti ranged from 1.8-2.5 mm and those of E. squamiceps were 1.4-1.9 mm. Etheostoma kennicotti hatched at 4.1-4.7 mm TL and E. squamiceps at 5.6-6.1 mm TL. Both species have 16 preanal myomeres and 18 or 19 postanal myomeres. Etheostoma kennicotti (<13.0 mm TL) has a more spherical, larger yolk sac and a smaller head length/TL than E. squamiceps. Etheostoma squamiceps has melanophores distributed postanally, while E. kennicotti has melanophores limited primarily to the yolk sac. A preliminary diagnostic characterization of the subgenus Catonotus based on larval traits is included.

Descriptions of eggs, larvae, and early juveniles of the Iowa darter, Etheostoma exile (Girard), from Lac Heney, Quebec

Descriptive morphology of egg, larval, and early juvenile stages of the Iowa darter, Etheostoma exile (Girard), from Lac Heney, Quebec, were examined using morphological, meristic, morphometric, and pigment characteristics. The Iowa darter is a phyto-lithophil spawning on aquatic macrophytes and exposed tree roots. Ova are weakly indented and range in diameter from 0.9 to 1.3 mm, with larvae presumably hatching at ca. 3.6 mmTL. The Iowa darter has 16–18 preanal myomeres (typically 17), and from 20–23 postanal myomeres. Pigmentation is superficially most similar to the yellow perch. A synopsis of the known aspects of the early life history is presented and distinctive morphological characteristics of syntopic percids are compared.

Egg and Larva Development of Brook Silversides from the Peace River, Florida

Abstract Brook silverside (Labidesthes sicculus) eggs, larvae, and juveniles were collected with a plankton net from the Peace River, Florida. Eggs had two or three attachment filaments (mode = 2) and a mean diameter of 1.2 mm. Oil globules were present in the yolk, and decreased from a mean of 22 after fertilization to one by the late embryo stage. Recently hatched protolarvae ranged from 4.7 to 5.6 mm total length and had six to seven and 28 to 31 postanal myomeres. The ratio of preanal length to total length increased as the anus migrated posteriorly during the metalarval phase; preanal myomere counts increased while postanal counts decreased. Pectoral anlages were present at hatching. By 8.0 mm, the base of the second dorsal and anal fins began to develop, and fin ray anlages were present in the caudal fin. Pelvic fin anlages appeared by 10.3 mm and all median fin rays were visible by 11.3 mm. The first dorsal fin developed between 11.3 and 15.5 mm. Metalarvae transformed into juveniles between 15.5 a...

Description and Identification of Mooneye, Hiodon tergisus, Protolarvae

Abstract Mooneyes hatch at about 7 mm total length as protolarvae with neither the stomodeum nor pectoral fin buds evident. They transform to the mesolarval phase between 12 and 13 mm while still retaining a considerable amount of yolk and most of their large anterior oil globule. The protolarvae possess about 54 myomeres, 30 anterior to the posterior margin of the vent. Snout to vent length is about 64% and snout to dorsal finfold origin length over 50% of the total length. Melanophore distribution remains essentially the same through most of the phase with melanophores scattered over the large yolk sac and in a continuous line along the dorsal surface of the intestine, midventrally posterior to the vent, around the end of the notochord, and middorsally towards the future insertion of the dorsal fin. In contrast to mooneye, goldeye, Hiodon alosoides, protolarvae have approximately four to eight additional postanal myomeres and lack melanophores on all surfaces posterior to the vent except occasionally al...

Identification of Eggs, Larvae, and Juveniles of the Rainbow Smelt, Osmerus mordax, with Comparisons to Larval Alewife, Alosa pseudoharengus, and Gizzard Shad, Dorosoma cepedianum

Abstract Eggs and larvae of the rainbow smelt, Osmerus mordax, were reared in the laboratory to 7.4 mm total length. Larger sizes were collected by plankton net from Lake Erie, Lake Ontario, and Cayuga Lake, New York. Manually stripped eggs were adhesive and demersal with a granular, yellow yolk. Egg diameter after fertilization and water hardening was 1.0 mm. The majority of eggs hatched between 183 and 195 h after fertilization at an average water temperature of 16.5 C. Average length of larvae at 195 h was 5.6 mm. Yolk absorption was complete at 6.4 mm. Pectoral fin development began before hatching. The dorsal, anal, and caudal fin rays began development at approximately 14 mm. The pelvic fins budded between 17 and 20 mm. All fin rays were complete at 36 mm. The adipose fin was complete at 29 mm. Separation of rainbow smelt from alewife (Alosa pseudoharengus) and gizzard shad (Dorosoma cepedianum) was accomplished using yolk sac position, preanal and postanal myomeres, and snout-to-vent length as a pe...

ウナギの前レプトケファルス期の仔魚について

The larvae of the Japanese eel, which were hatched from fertilized eggs obtained from silver eels matured artificially by hormone treatment and kept in sea water at 23°C, were observed. 1) The newly hatched larvae measured about 2.9mm in body length and had about 40 somites, Their mouths and anuses were still unopened. Their membranous fins developed well, but their other fins could not be found. Very few pigments were recognizable only in the caudal portion of the embryo. 2) The larvae survived for about five days. They respectively measured about 4.8mm, 5.3mm, 5.9mm and 6.2mm in body length on the second, third, fourth and fifth days respectively after hatching. By the sixth day, when the yolk sacs of the larvae were almost absorbed, most larvae showed a curvature of their tails. The average length of the surviving larvae was about 5.8mm. 3) By the third day after hatching, mouths and anuses opened and pectoral fins appeared. The brain differentiated into three parts, showing a large fourth ventricle. The larvae, on the sixth day, showed conspicuously developed jaws with clear tooth anlagen. Fifty-three preanal and about 48 postanal myomeres were counted in the larvae.