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Apalone spinifera

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA TESTUDINES TRIONYCHIDAE

Scientific Name: Apalone spinifera
Species Authority: (LeSueur, 1827)
Infra-specific Taxa Assessed:
Common Name(s):
English Spiny Softshell Turtle
Synonym(s):
Amyda spinifera subspecies hartwegi Conant & Goin, 1948
Apalone hudsonica Rafinesque, 1832
Aspidonectes asper Agassiz, 1857
Aspidonectes emoryi Agassiz, 1857
Platypeltis agassizii Baur, 1888
Trionyx ater Webb & Legler, 1960
Trionyx spinifer LeSueur, 1827 subspecies guadalupensis Webb, 1962
Trionyx spinifer LeSueur, 1827 subspecies pallidus Web, 1962
Trionyx spiniferus LeSueur, 1827
Taxonomic Notes: Includes six widely recognised subspecies: Apalone spinifera spinifera (LeSueur, 1827), A.s. aspera (Agassiz, 1857), A.s. emoryi (Agassiz, 1857), A.s guadalupensis (Webb, 1962), and A.s. pallida (Webb, 1962); Apalone spinifera atra (Webb & Legler, 1960) has at times been treated as a full species, but is here treated as a subspecies of spinifera based on recent genetic and morphological studies (McGaugh 2008, McGaugh and Janzen 2008, McGaugh et al. 2008).

The previously recognized subspecies Apalone spinifera hartwegi (Conant & Goin, 1948) is now considered a synonym of A.s. spinifera, based on its limited morphological and molecular distinctiveness (McGaugh et al. 2008).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2013
Date Assessed: 2010-08-01
Assessor(s): van Dijk, P.P.
Reviewer(s): Horne, B.D., Mittermeier, R.A., Philippen, H.-D., Quinn, H.R., Rhodin, A.G.J., Shaffer, H.B. & Vogt, R.C
Contributor(s): Flores-Villela, O., Hammerson, G.A., Lavin, P. & Mendoza-Quijano, F.
Justification:
Widespread, cryptic and locally common species with an adaptable life history and high reproductive potential by turtle standards. Harvest rates appear not significant enough to have led to documented localised declines. It is listed as Least Concern.

Geographic Range [top]

Range Description: Apalone spinifera inhabits southernmost Ontario and Quebec in Canada, northern Mexico from Chihuahua to Tamaulipas, and most of the United States East of the Rocky Mountains. Occurs nearly throughout the Mississippi-Missouri-Ohio system, as far upstream as Wyoming, the Great Lakes region, Ottawa, southern St.Lawrence and Hudson systems, the Colorado system, the Rio Grande system, Atlantic drainages from Cape Fear to the Saint Marys River, and Gulf drainages from the Appalachicola to the Rio Soto de Marina.

Apalone spinifera spinifera: Most of the Mississippi-Missouri-Ohio and Great Lakes systems, with an isolated population in the Hudson valley.
Apalone spinifera atra: endemic to the Cuatro Cienegas basin of Coahuila, Mexico.
Apalone spinifera aspera: from southern North Carolina to Mississippi. 
Apalone spinifera emoryi: Rio Grande - Pecos basin of Texas-New Mexico, USA, and Chihuahua to the Rio Soto de Marina in Tamaulipas, Mexico. Also inhabits the Colorado system of Arizona-California (and adjoining Utah, Nevada and New Mexico), documented to be introduced (Miller 1946, Iverson 1992, Ernst et al. 1994). Co-occurs with Apalone s. atra in the Cuatro Cienegas basin, where it prefers riverine sections (Webb and Legler 1960).
Apalone spinifera guadalupensis: Central Texas.
Apalone spinifera pallida: Louisiana, northeastern Texas and southern Oklahoma.
Countries:
Native:
Canada (Ontario, Québec); Mexico (Chihuahua, Coahuila, Nuevo León, Tamaulipas); United States (Alabama, Arizona - Introduced, Arkansas, California - Introduced, Colorado, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada - Introduced, New Jersey - Introduced, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah - Introduced, Vermont, Virginia, West Virginia, Wisconsin, Wyoming)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: A widespread and generally common species. Depending on site and habitat type, Spiny Softshells constitute between less than 1% to 67% numerically of all turtles encountered in turtle community surveys (reviews in Ernst et al. 1994, Ernst and Lovich 2009).

Apalone spinifera emoryi was considered common in the Rio Florida and Lago Toronto in Coahuila, Mexico, in 1958 (Williams et al. 1960). The subspecies emoryi has apparently a substantial capacity for establishing itself in new areas, if its occurrence in the Colorado rivers system and the Cuatro Cienegas basin are indeed based on introductions.

Apalone spinifera atra: While quantitative data are not available, Apalone s. atra was not rare in the 1950s: ‘the heads of several [A.s.] ater could usually be seen at dusk by scanning the surface of the pond with binoculars’ (Webb and Legler 1960). No recent population data have been made widely available. In recent years it was considered a rare species, Smith and Smith (1979) considered it was extinct due to hybridization, but Flores-Villela (pers. comm. 2005) collected the species around 1990.

The morphological continuity between ater and emoryi after some generations in sympatry have variously been interpreted as intergradation between subspecies of Apalone spinifera, or as hybridisation between two species that were not reproductively isolated  (Webb and Legler 1960, Webb 1962, Smith and Smith 1979, McGaugh 2008, McGaugh and Janzen 2008, McGaugh et al. 2008).
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Apalone spinifera is a generalist aquatic species that inhabits almost any type of permanent waterbody, from fast-flowing large rivers to lakes and reservoirs to small marshy creeks, farm ponds and desert springs. A soft bottom with some aquatic vegetation appears required, as are sand bars or mudbanks for basking, while accumulations of underwater debris are preferred microhabitat (Ernst et al. 1994).

Spiny Softshells are predominantly carnivorous, feeding on crayfish and other crustaceans, fish (carrion and small live fish), insects (aquatic larvae and fallen adults), other aquatic invetrtebrates, and some vegetable matter (reviews in Webb 1962, Ernst et al. 1994).

Males mature at relatively small size (8-10 cm plastron length/about 11-14 cm carapace length (CL), 130 grams or more), while females mature at CL over 28 cm (Webb, 1962:562). Maximum size of females is 54 cm CL, males maximum 21.6 cm. Maximum longevity is probably well over 30 years (Breckenridge 1955, in Ernst et al. 1994). Females normally produce two clutches per year, nesting mainly in June and July. Clutches usually comprise 12-18 eggs, extremes of clutch size are 4-39 (review by Ernst et al. 1994).

Apalone spinifera atra: Restricted to the Cuatro Cienegas basin, an hourglass-shaped intermontane basin of about 50 km long and 8-24 km wide (about 600 km2), its floor being at 720 m altitude. Much of the central part of the basin is marshy, with dry sandy slopes leading up the rocky valley slopes. A number of deep (up to several meters) ponds occur within the marshy area, and retain crystal-clear water throughout the year. About half the bottom is covered by dense submerged aquatic vegetation (mainly Chara), the other half is bare sediment. Waterlilies grow in the shallow parts, and thick stands of cattails (Typha) and Eleocharis fringe the ponds. Water temp is about 27-29 degrees C. Ponds may be separated from dry nesting areas on the slopes by substantial distances (several 100 m.) of flat marshy grassland. (Webb and Legler 1960). Within the basin, A. s. atra has been recorded only within the deep ponds, but not in riverine situations (Webb and Legler 1960, Webb 1962). Limited information of food indicates that the animals feed selectively on aquatic insect larvae (Webb and Legler 1960). Reproductive data on dissected type series (limited to smaller individuals) suggest that A. s. atra matures at similar sizes as other spinifera subspecies (Webb and Legler 1960), i.e. males mature at CL over 15 cm, and females at CL over 28 cm. No information is available on clutch size or frequency, on age at maturity, or longevity of atra.
Systems: Terrestrial; Freshwater

Use and Trade [top]

Use and Trade: Large numbers of adults (mainly females) continue to be exported from the USA to East Asia since the late 1990s, as well as large quantities of hatchlings (from farms/ranches and from wild-harvested eggs); this trade has fluctuated as China reduced imports in response to veterinary concerns and the maturation of domestic turtle aquaculture operations.

Declared exports of Apalone spinifera are recorded in the LEMIS database, but available numbers do not allow separating the data by subspecies, area of origin, or whether collected from the wild or produced in captive conditions. Export numbers of recent years are: 1999-2002: under 1,000 each year; 2003: 16,131; 2004: 22,120; 2005: 31,113; 2006: 56,356; 2007: 32,119; and 2008: 120,723 individuals recorded as exported.

Threats [top]

Major Threat(s): While Apalone spinifera has long been exploited for local consumption (Webb 1962) and more recently for export of adults for food and of hatchlings as pets and for Asian farming operations, and some individuals are destroyed as nuisance by-catch by recreational fishermen, are run over when crossing roads, and populations are affected by pollution, water diversion, and water infrastructure development, the species as a whole is not threatened in its existence by present processes. However, certain subspecies and populations are considered to be less secure.

Apalone spinifera spinifera:  The Lake Champlain and Hudson River valley populations are considered to warrant conservation attention.

Apalone spinifera atra: Main recorded threat is hybridisation or intergradation with Apalone spinifera emoryi, which entered the Cuatro Cienegas basin from the Rio Grande through the Rio Nadadores and Rio Salado. A number of previously isolated ponds and wetlands had been drained and interconnected by a network of canals before 1960 (probably before 1920) for agricultural purposes (Webb and Legler 1960, Smith and Smith 1979), but apparently not connected to the Rio Chiquito. How emoryi transferred from the Rio Nadadores to the isolated ponds is unclear; Webb (1962) considered overland dispersal during rain, subterranean connections, and human transport as possibilities. Apalone spinifera emoryi was present in the Cuatro Cienegas basin as early as 1938-39 (Schmidt and Owens 1944); specimens of both forms collected in 1958 were clearly separable (Webb and Legler 1960) and apparently showed no indication of hybridisation at least 20 years after first contact. However, Webb (1962) subsequently noted that not all atra showed all diagnosic characteristics, and that some approached the condition shown in emoryi. Within the basin, emoryi shows a preference for riverine situations, with only few individuals recorded from ponds (Webb and Legler 1960, Webb 1962). Some trade and consumption of softshell turtles has occurred in the Cuatro Cienegas basin at least in the 1950s (Webb 1962). The survival of atra is dependent on the ecological and hydrological integrity of the relatively small Cuatro Cienegas ecosystem. The Cuatro Cienegas basin has been extensively altered in its hydrology by digging canals to supply water to a steel mill in Monclova, and for local agricultural irrigation. Roads, railroads, pipelines and other infrastructure for industrial, logistic and tourism and recreational purposes have impacted the ecosystem, and some of these environmental impacts continue. Roads have created direct-mortality impacts. (Groombridge 1982, and references therein). Provided no further major engineering works impact the ecological integrity of the Cuatro Cienegas basin, and the protected area regulations are adhered to, atra has probably surmounted its worst environmental impacts.

Apalone spinifera emoryi
: Populations in Mexico are impacted by water diversion and reduced groundwater levels from irrigation and groundwater pumping.

Apalone spinifera guadalupensis: The status of populations of this Texas endemic are apparently poorly known.

Conservation Actions [top]

Conservation Actions: Apalone spinifera as a whole is managed as a non-game resource in much of the USA, and occurs in a wide variety of sites and habitats under various degrees of protective measures. Better understanding of harvest levels and population dynamics, and population monitoring, would be welcome. Conservation assessments for the subspecies guadalupensis should be carried out as a matter of priority.

Introduced population of emoryi in the Colorado River basin is probably beyond control.

Apalone spinifera atra is included in Appendix I of CITES, prohibiting any form of commercial international trade, and is protected from exploitation under Mexican wildlife and natural resource legislation. Its entire range falls within the 843 km2. Cuatro Cienegas Flora and Fauna Protection Area (IUCN Category VI), established in 1994. Much more information on the species’ natural history is urgently needed, and an investigation of the ecological and genetic effects of the presence/invasion of A. spinifera emoryi in Cuatro Cienegas is a top priority.

Citation: van Dijk, P.P. 2013. Apalone spinifera. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 October 2014.
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