Empetrichthys latos

Empetrichthys latos
Empetrichthys latos
Empetrichthys latos
Empetrichthys latos
Empetrichthys latos
English Name: 
Pahrump Poolfish
Original Description: 

  MILLER, R. R. (1948): The cyprinodont fishes of the Death Valley system of eastern California and southwestern Nevada. Miscellanous Publications, Museum of Zoology, University of Michigan No.68: pp 1-155

Holotype: 

  Collection-number: University of Michigan Museum and Zoology, Cat. No. UMMZ-141855.

  The Holotype is an adult female of 43mm standard length, collected by R. R. Miller and his wife Frances on October the 5th, 1942. Together with the Holotype, 143 Paratypes (originally UMMZ-140489), 15 to 48 mm long, and 34 Paratypes (UMMZ-132915), 10 to 50 mm long, collected by R. R. Miller and Alex J. Calhoun on July 16th, 1938, from the outlet of the main spring pool at Manse Ranch were taken. 

  The left picture shows a drawing of an immature male from Manse Spring, the right one an adult male Paratype (UMMZ-140489) of 34mm from the same locality. Concerning types of the other two described subspecies and pictures go to the chapter "Remarks":

 immature male of Empetrichthys latos latos adult male of Empetrichthys latos latos

Terra typica: 

  The Holoype of this species was collected in the main spring pool on Manse Ranch, Pahrump Valley, Nye County, Nevada.

Etymology: 

  The species' name latos refers to the wide mouth of the species as compared to Empetrichthys merriami, the type species of this genus. The species epithet can be derived from Latin with "latus" meaning broad and "os" mouth, so together meaning "widemouth". 

  The genus was erected by Gilbert in 1893 and the generic name can be derived from the ancient Greek. The word ἔμπετρος (émpetros) means "into the rock" with the prefix ἔμ- (én) meaning into and πετρος (petros) the rock. The last part of the word ἰχθύς (íchthús, íchthýs) is the Greek word for fish, herewith the generic name can be translated with "fish that lives or hides in rocks".

Synonyms: 

  none

Distribution and ESU's: 

  Empetrichthys latos was historically known from three springs being separated from each other by less than 12km beeline in the Pahrump Valley, Nye County, Nevada, namely Raycraft Ranch Spring, Pahrump Ranch Spring and Manse Spring (type locality). Water pumping in the second half of the 1950's drove the population of the Pahrump Ranch extinct while the Raycraft Ranch Spring was bulldozed and filled in 1955. The only remaining population from the Manse Ranch was relocated in the early 1970's to several introduction sites, when declining water levels due to groundwater pumping for agricultural development made the desiccation of Manse Spring predictable. Today, all known populations live outside of the native range of this species (for more information go to the chapter "Remarks").

 

  ESU ist short for Evolutionarily Significant Unit. Each unit expresses an isolated population with different genetic characteristics within one species. ESU's can be defined by Molecular geneticsMorphology and/or Zoogeography and help in indicating different phylogenetic lineages within a species. The abbreviation for an ESU is composed of three letters of the genus, followed by the first two letters of the species name and an ongoing number in each species.

  In the subfamily Empetrichyinae, no ESU's were in use so far. To align with the livebearing subfamily Goodeinae, the GWG wants to bring a system in use based on John Lyons' naming for this subfamily. According to morphological differences and the description of three subspecies, three ESU's ae recognized: Empla1 from the Raycraft Ranch (E. l. concavus) and Empla2 from the Pahrump Ranch (E. l. pahrump) have to be regarded extinct. The only ESU still existing, but inhabiting exclusively habitats outside of its natural range (Manse Ranch) is Empla3 (E. l. latos).   

 

  The left map shows the Central Nevada Desert Basins Accounting Unit (HUC 160600) of the Great Basin Region (HUC 16), the right map the Ivanpah-Pahrump Valleys Cataloging Unit (HUC 16060015). The names of watersheds here in use are the ones officially used by the the U.S. Geological Survey:

 Empetrichthys merriami basin Empetrichthys merriami subbasin

Status : 

  International Union for Conservation of Nature (IUCN): Critically Endangered

  U.S. Fish & Wildlife Service (ECOS): Endangered

Habitat: 

  In the following lines, we give R. R. Miller the chance to describe himself the three springs where he was able to find the Pahrump Poolfish: "The main spring pool at Manse Ranch is about 50 feet (15.2m) wide at the head, 10 feet (3m) wide at the outlet, and 60 feet (18.3m) long. It is 1 to 6 feet (0.3 to 1.8m) deep and has a silt bottom. The water is crystal clear and chalky blue in a deep hole near the center of the spring. On October 5, 1942, vegetation noted was thick water cress, Chara, green algae, and a fine-leaved Potamogeton. The shore is a low bank, bordered by cottonwood (Populus fremonti?) and willow, which well shade the pool. The current is moderate in the pool and swift in the outlet. About 50 yards (45.7m) above is a much smaller spring which flows into the head of the pool just described; it contained no fish life. The temperature of the main spring, as recorded by several investigators over a period of 26 years, is very constant, about 24°C. (23.3 to 24.0°C). The 2 main springs on Pahrump Ranch, which rise about 200 yards (183m) east of the principal ranch houses, are used extensively for irrigation. Until recently the northern spring contained native fish life, but it was greatly altered by dredging in 1941, and only a few carp were observed there in 1942. The southern spring still harbored a few fish in 1942, but in October of that year most of the population of pahrump was in a marshy area about 200 yards from the source of the southern spring. As shown by readings over a 26-year period, the temperature of the spring sources is constantly about 25°C (24.7 to 25.0°C.); that of the outlets varies somewhat and is usually less than 25°C. E. latos concavus was collected on Raycraft Ranch from the spring-fed pond, 5 to 25 feet (1.5 to 7.6m) wide and about 40 feet (12.2m) long, and its outlet ditch, 1 to 4 feet (0.3 to 1.2m) wide. The temperature of the spring on October 5, 1942, was 25.3°C, slightly warmer than were the springs on either Manse or Pahrump ranches. The water in the spring pond and outlet was clear but easily roiled because of a bottom of silt and trash. Vegetation noted in 1942 was water cress, Typha, and grass. The current in the spring was slight, but rather swift in the outlet. The depth of water was not over 1.5 feet (0.45m). The shore consisted of low banks, willows, and meadowland. According to Waring (1920) this spring has a flow of about 10 gallons (37.9l) a minute. Empetrichthys was not common, perhaps because introduced carp were also present."

Biology: 

Despite the constant temperature of the type location, the fish is able to survive a wide range of temperatures, ranging from 4°C to more than 30°C.

   At the type location spawning occured from January to July, with a peak in April or later in several habitats. The average brood size is 14 (up to 28), the eggs hatched in 7-10 days. Average length of the fry is 6.2mm.

Diet: 

Empetrichthys latos is an opportunistic omnivore and feeds on a wide variety of available plant and animal material, especially algae and invertebrates. Taking in consideration a relatively short intestine ( about 1 1/2 times of TL), the biserial conical teeth with the outer series enlarged, this species seems to be rather carnivorous.

Size: 
According to Miller (1948): 47mm (E. l. latos), 42mm (E. l. pahrump) and 39mm (E. l. concavus). The average size of the three subspecies only differs from 32mm to 35mm. Females are generally larger than males.
Colouration: 

On its slender, elongate body, Empetrichthys latos shows a dark longitudinal streak, which tends to disappear in large adults. The colouration of the body is a greenish brown with dark blotches. Courting males may lose their spots and show a silver-blue, iron-like colour. Dorsal, anal and caudal fins are orange-yellow.

Remarks: 

  Robert Miller described in his paper from 1948 in total three subspecies, according to the three populations he found in the three springs. The differences are morphological, mostly fin sizes and distances between fins and head profiles. Living in small populations in isolated springs may easily drive a population in a certain direction and cause morphological as well as genetical differences, for last ones, the populations haven't been studied (and it might be meanwhile impossible due to conservation practices). However, modern taxonomy inclines to refuse the taxon "subspecies", as either there are differences between populations that qualify for a separate taxon, then these populations are regarded species, or they do not. In this case, alternative expressions like clades, clusters, lineages, populations, subpopulations, or ESU's come in use. Anyway, we don't want to violate the existing situation in the Pahrump Poolfish, though we would also prefer to talk about lineages or ESU's instead of subspecies, so we decided to place the information we usually try to give about Holotypes, habitat and terrae typicae here in the chapter "Remarks".

  Empetrichthys latos concavus: University of Michigan Museum and Zoology, Cat. No. UMMZ-141857.

  The Holotype is an adult female of 39mm standard length, sampled by R. R. Miller and his wife Frances on October 5th, 1942. The Collection-numbers of the Paratypes are: UMMZ 140491 (21 specimens) and USNM 112071 (5 specimens), 17 to 40mm long. The type location was a spring on the Raycraft Ranch, about 0.5 miles (0.5km) north of the Pahrump Ranch, Pahrump Valley, Nye County, Nevada. The species epithet can be derived from the Latin with the prefix con- meaning "with" and cavus "the hollow", therefore concavus can be translated with "with a hollow", refering to the marked concavity of the top of the head.

  Empetrichthys latos pahrump: University of Michigan Museum and Zoology, Cat. No. UMMZ-141856. The Holotype is an adult female of 35mm standard length, seined by R. R. and F. H. Miller on May 5th, 1942. The Collection-numbers of the Paratypes are: UMMZ 140490 (originally 142, now 130 specimens); USNM 112073 (ex UMMZ-140490, 10 specimens), 14 to 36mm long. The type location is a marshy overflow of a spring-fed ditch on Pahrump Ranch, 6 miles (9.7km) northwest of Manse Ranch, in Pahrump Valley, Nye County, Nevada. This subspecies "is named pahrump after the valley in which it is found, and more particularly for Pahrump Ranch, which is the more precise type locality."

  The left picture shows an adult male Paratype of Empetrichthys latos concavus (UMMZ-140491), 34mm long, and the right one of Empetrichthys latos pahrump (UMMZ-140490), 32mm long:

 male Paratype of E.l. concavus male Paratype of E.l. pahrump

 

 

 The remaining subspecies latos could only survive through a couple of translocations

  a) Los Latos Pool in an isolated canyon above the Colorado River (Soltz and Naiman, 1978). This site was flooded in the 1970's and its population got lost.

b) Corn Creek Springs, northwest of Las Vegas on the Desert National Wildlife Range, Nye County. The transplant to Corn Creek Spring took place in 1971 and involved 29 fish. Soltz and Naiman (1978) reported about relatively large reproducing populations there. They indicated that a third population was established in an artificial refugium in Ash Meadows but that it died out in 1977. The population in Corn Creek Springs was extirpated in the 1990's due to the introduction of crayfish and bullfrogs. In 2003 fish were reintroduced to a secure, but smaller part of Corn Creek Spring and seem to be stable there.

c) Shoshone Ponds, White Pine County, about 40 miles southwest of Ely. The ponds were stocked in 1972 with 16 Empetrichthys latos from Corn Creek or Manse Ranch Spring. The fish were extirpated in 1974 due to vandalism, but in 1976, another 50 fish were transplanted to the site. This population counted 1989 about 450 individuals.

In 1983 fish were introduced in unrecorded number to a reservoir at Spring Mountain Ranch State Park, Clark County, Nevada, after eradication of exotic species. Since then, this is the largest and most stable population of Empetrichthys latos. Estimations in 2004 reached nearly 30.000 specimens.

Clemmer reported in 1992 about additional introduction sites and stable populations at Chimney Springs and Hot Creek, Nye County and Sodaville Springs, Mineral County.

 

   Miller (1948) reported, that - including E. merriami - "some of the forms have an extremly small population, with effective breeding sizes as low as 50. The introduction of other fishes into its native spring habitat contributed also to the decline of the Pahrump poolfish. For instance, Deacon et al. (1964) reported that the establishment of goldfish Carassius auratus in Manse Spring resulted in population depression.

   Species of the subfamily Empetrichthyinae are oviparous fishes. Parenti (1981) proposed the Empetrichthyinae as sister group to the Goodeinae and used the name Goodeidae to encompass the two subfamilies. This narrow relationship has been supported by several studies since the 1980's (Webb, Domínguez). Both genera of this subfamily share the lack of pelvic fins.