Amblyopsis hoosieri Niemiller, Prejean & Chakrabarty

Chakrabarty, Prosanta, Prejean, Jacques A. & Niemiller, Matthew L., 2014, The Hoosier cavefish, a new and endangered species (Amblyopsidae, Amblyopsis) from the caves of southern Indiana, ZooKeys 412, pp. 41-57 : 45-50

Amblyopsis hoosieri Niemiller, Prejean & Chakrabarty sp. n. Figures 4A, 5-7; Table 1

Amblyopsis spelaea “N” Niemiller et al. 2013d: pg. 9 (Fig. 3)

Amblyopsis spelaea : Simon 2011: pg. 230-231; Fig. 146 (in part)

Amblyopsis spelaea : Poulson 1963: pg. 267, 269 Upper Twin, Spring Mill (in part)

Amblyopsis spelaea : Woods and Inger 1957: pg. 241, 243-245; Fig. 5 (in part)

Type material.

Holotype. INHS 106675, Bronson’s Cave (White River Dr.) Spring Mill State Park, Lawrence County, Indiana, USA; 38°44', -86°25'; 9 December 1962, W.U. Bringham [formerly in lot 102504]

Paratypes. INHS 40424 (n=12 in ETOH; n=2 cleared and stained), Bronson’s Cave (White River Dr.) Spring Mill State Park, Lawrence County, Indiana, 5 April 1964, W.U. Brigham, G.W. Barlow & J. Mertz; INHS 60574 (n=1), Spring, (Lost River Dr.) Near West Baden, Orange County, Indiana, 18 January 1904, N.H. Haden; INHS 102504 (n=4), same data as holotype; LSUMZ 17419 (n=1), same as UMMZ 157175, formerly of that lot; LSUMZ 17420 (n=1), same data as UMMZ 65000, formerly of that lot; UMMZ 65000 (n=2), Twin Caves, near Mitchell, Lawrence County, Indiana, 17 May 1924, Hubbs & party; UMMZ 90379 (n=2), Sibert’s Well Cave, beside Wyandotte Cave, Indiana, 17 August 1930, P. Hickie; UMMZ 113550 (n=1), Lost River, Indiana, ca. 2 mi NE of Orangeville, September 1935, J.J. & W.P. Petravicz; UMMZ 114890 (n=2), Donaldson’s Cave, Spring Mills State Park, Lawrence County, 16 June 1934, A.E. Emerson; UMMZ 144604 (n=1), Stream in Sibert’s Well Cave, Wyandotte, Crawford County, Indiana, 01 October 1942, L. Hubricht; UMMZ 146992 (n=1), Stream in Sheep Cave, near Wyandotte, Crawford County, Indiana, 01 September 1939,, L. Hubricht; UMMZ 146994 (n=3), Stream in Bronson Cave, Spring Mill State Park, Lawrence County, Indiana, 2 September 1939, L Hubricht; UMMZ 157174 (n=1), “possibly” Donaldson farm caves near Indiana University, Indiana, C.H. Eigenmann; UMMZ 157175 (n=1), same as previous lot; UMMZ 157176 (n=1), same as previous lot; UMMZ 160944 (n=1), Twin Cave, Mitchell, Lawrence County, Indiana, 18 June 1924, F.N. Blanchard; YPM 25304 (n=2), Donaldson Cave, Spring Mill State Park, Lawrence County, Indiana, 21 December 2007, M.L. Niemiller et al.; YPM 25305 (n=1), Blue Springs Caverns, Lawrence County, Indiana, 21 December 2007, M.L. Niemiller et al. [Note tissue samples and published sequences are available from paratypes in YPM 25304 and 25305 ( Niemiller et al. 2013d) and these correspond to genseq-2 following the nomenclature of Chakrabarty et al. (2013). GenBank numbers for these sequences from the paratypes are reported in Table 2.]

Morphological diagnosis.

Amblyopsis hoosieri can be distinguished from its only congener, Amblyopsis spelaea , by having a more plump, fleshy and rounded body (versus sculpted and thin) with Bibendum-like wrinkles along myomeres (versus tight skin) and by having rounder pectoral fins (versus pointed; Figs 4-6). Additionally, the mechansensory papillae on the body and caudal fin are reduced in size and less elevated on the skin (versus conspicuous in Amblyopsis spelaea ).

Molecular diagnosis.

Average uncorrected pairwise genetic distance at the mitochondrial NADH dehydrogenase 2 (nd2) locus between Amblyopsis hoosieri and Amblyopsis spelaea is 3.1%, with 27 mutations separating the two species. Amblyopsis hoosieri and Amblyopsis spelaea can also be readily diagnosed using molecular data at the nuclear rhodopsin gene, a G-coupled photoreceptor expressed in the retina of the vertebrate eye. All rhodopsin sequences of Amblyopsis hoosieri code for the amino acid glutamine (Q) at position 184, whereas Amblyopsis spelaea possesses a point mutation that results in a premature stop codon at this position. In addition, Amblyopsis hoosieri rhodopsin codes for the amino acid valine (V) at position 254, whereas Amblyopsis spelaea codes for the amino acid phenylalanine (F). A single mutation in intron 1 of ribosomal protein S7 (s7) also distinguishes the two species.

Description.

Robust, blind (eye not developed, Fig. 7), unpigmented cavefish typically reaching between 60-80 mm in adult standard length. Head large (about ¼ body length) flat dorsally but broad; head widest part of body. Body widest at operculum, narrows to caudal fin. Body rectangular, dorsal and vertical profile of body nearly symmetrical; deepest point at dorsal-fin origin. Fleshy protuberance present anterior to dorsal-fin origin; similar protuberance at anal-fin origin. Body narrows posterior to dorsal- and anal-fin origins, narrowest point at midpoint of caudal peduncle. Body plump, wrinkly in appearance (as in Bibendum) prominent deep myomeres present. Deep groove on ventral side of body from operculum and anus to pelvic fin. Scales inconspicuous and cycloid.

Superficial mechanosensory neuromasts on papillae ( Eigenmann 1909, Niemiller and Poulson 2010) present in rows of 5-30 on head. Papillae concentrated at mouth; fewer posteriorly on head. Most rows of papillae vertical, far fewer horizontal. Horizontal rows typically connect two to four other vertical rows. Most mechanosensory papillae on dorsal side of head concentrated and aligned posterior to, or between, nares. No mechanosensory papillae in central area of dorsal region of head. Papillae present dorsal to braincase in two horizontal rows. No lateral line on body. Mechanosensory papillae on body much smaller than those on head and aligned in vertical rows; some scattered papillae near dorsal-fin base. Inconspicuous papillae present on caudal fin in horizontal rows of two or three in both dorsal and ventral half of fin, vertical row present at base.

Anterior nares small, tube shaped; posterior nares slightly larger with small anterior flap, but otherwise circular. Lips somewhat thin and fleshy. Lower jaw slightly longer than upper jaw.

Vertical through dorsal-fin origin between more anterior pelvic-fin origin and more posterior anal-fin origin. Anal-fin and dorsal-fin insertions near same vertical plane. All fins relatively short and rounded. Anus located anteriorly on body, behind isthmus of united gill membranes (i.e., jugular). Caudal skeleton upturned and asymmetrical (externally appearing homocercal), with last half centrum (preural 1 + ural 1) including hypural (3-X; following Rosen 1962) and entirely associated with dorsal half of caudal fin. Five or six principal caudal-fin rays supported by each hypural plate (ventral hypural 1+2; again following Rosen 1962).

Branchiostegals six in number, robust and prominent. Papilliform flap at dorsal origin of operculum. Six or seven gill rakers on ceratobranchial of first gill arch. Rakers short, stubby and denticulated. Central and upper tooth plates also heavily denticulated.

Buccal teeth villiform, in three to five rows. Individual teeth unicuspid, slender and long; teeth deeply embedded in mouth so only top 1/3 visible. Teeth recumbent, particularly those on upper jaw. Palatine and vomerine teeth also present.

Body uniformly depigmented, including inside mouth. Body pinkish-white, reddish near gills, fins transparent. In alcohol, body color uniformly yellowish/beige, fins opaque yellow.

Etymology.

The specific epithet hoosieri is in reference to this species being from the state of Indiana. It is also a reference to Indiana University, where biologist Carl H. Eigenmann was a Professor of Zoology and studied blind cave vertebrates, including populations of Amblyopsis hoosieri in Lawrence County just to the south of Bloomington ( Eigenmann 1909). Indiana University was also home to the Father of American Ichthyology, David Starr Jordan, for most of his illustrious career. We derive the specific epithet from the proper noun “Hoosier.” Notably, the senior author of the manuscript is a fervent fan of Indiana Hoosier basketball while the first author is an alumni of the University of Michigan and is not. Suggested common name, Hoosier Cavefish.

Distribution.

Amblyopsis hoosieri occurs in caves developed in carbonate rock of the Crawford-Mammoth Cave Uplands and Mitchell Plain in the South-Central karst region of Indiana (Fig. 2) within the area that remained ice free throughout the Pleistocene Epoch ( Woods and Inger 1957, Frushour 2012). Caves within the distribution of Amblyopsis hoosieri are primarily developed in Mississippian-aged limestones and carbonates belonging to the St. Louis and St. Genevieve Limestone (Frushour 2012). The northernmost locality occurs 16 km from the glacial maxima of the Illinoian glaciation. The distribution of Amblyopsis hoosieri is bounded to the north by the East Fork White River and the south by the Ohio River. The species has been documented from at least 74 localities in Crawford, Harrison, Lawrence, Orange and Washington counties, including 68 cave systems and six springs ( Keith 1988, Pearson and Boston 1995, Lewis 2002a, Niemiller and Poulson 2010, Niemiller et al. 2013d). Amblyopsis hoosieri is known from the Lower White, Lower East Fork White, Patoka and Blue-Sinking watersheds.

Habitat.

Amblyopsis hoosieri is found primarily in larger cave streams at or near the water table where it has been observed in pools with low flow at depths as shallow as 0.1 m to> 2 m deep. Amblyopsis cavefishes from Indiana have been found in association with silt-sand, gravel, cobble and bedrock substrates ( Poulson 1963, Pearson and Boston 1995, Niemiller and Poulson 2010). A preference for larger pools with relatively deep, slow-moving water with large breakdown boulders has been noted ( McCandless 2005). During high flow conditions, cavefish seek refuge under ledges, in crevices or in areas of breakdown ( Niemiller and Poulson 2010). These habitats and preferences are similar to those found in Amblyopsis spelaea (reviewed in Niemiller and Poulson 2010).

Life history.

Poulson (1960, 1963) provided the most significant study on the ecology of the species described herein as Amblyopsis hoosieri based primarily on cave populations near Mitchell in Lawrence County, Indiana, which is reviewed in Niemiller and Poulson (2010). Amblyopsis hoosieri has a well-defined annual reproductive cycle ( Poulson 1963, Niemiller and Poulson 2010). Breeding presumably occurs during high water levels from February through April. Females brood eggs in their branchial cavities until hatching and continue to care for fry until yolk reserves are depleted 4-5 months later ( Eigenmann 1909, Niemiller and Poulson 2010). Fry appear in late summer into early autumn. Growth rates are estimated at 1.0 mm month-1 but decline with age ( Niemiller and Poulson 2010). Sexually maturity is likely reached in 3-4 years ( Poulson 1963). Longevity is unknown but estimated to be at least 12-15 years (but perhaps 20+ years) based on growth rates and scale formation ( Louis 1999, Niemiller and Poulson 2010). Documented prey of Amblyopsis hoosieri includes copepods, isopods, and amphipods. Larger individuals will feed on small crayfish ( Poulson 1963, Niemiller and Poulson 2010). Predators have not been documented in nature and it’s thought that individuals of Amblyopsis are one of the top predators in cave systems they inhabit ( Niemiller and Poulson 2010).