Milyeringa brooksi, Chakrabarty, 2010

Chakrabarty, Prosanta, 2010, description of a new blind cave-fish from Australia, Milyeringa brooksi, n. sp., Zootaxa 2557 (1), pp. 19-28 : 22-26

Milyeringa brooksi , new sp.

Holotype:— WAM P28330-001 , Pilgonaman Well, 22°11’S, 113° 52’E, 8 July 1984 collected by M. Newton ( Fig. 2 , 3 ; Table 2).

— LSUMZ 13637 , Pilgonaman Well, 22° 11’ 30.5"S, 113° 52’ 00.1"E, 21 May 2009, AUS-6- 2009, 1:15-1:40pm, collected by P. Chakrabarty, D. Brooks, and Annemarie Noël ; WAM P29242 (n=2), 22° 12’S, 113° 51’E, 19 May 1983 collected by B. Vine et al.

Diagnosis:— Milyeringa brooksi is distinguished from its only congener ( M. veritas ) by the following features: (1) 10–12 vertical lines of sensory papillae from pectoral-fin base to caudal fin base ( Fig. 3 , 4 ) versus inconspicuous and/or dispersed sensory papillae on body) and (2) by molecular synapomorphies listed in Table 3. In addition, M. brooksi adults are typically shorter than M. veritas individuals (max length recorded <40 mm SL vs. up to 53 mm SL), posterior nostril tubular in M. brooksi with a skin flap (versus posterior nostril typically simple and round in M. veritas ) and by typically having conspicuous papillae on the dorsal aspect of head. Pattern of sensory papillae in M. brooksi present in four lines on lateral and medial edge of frontal bones near posterior edge of head and by four rows of sensory papillae between left and right nostril (two rows on each side of midline) running in parallel, these anterior papillae extend only slightly past posterior nostril on each side of head (versus variable condition found in M. veritas individuals which have either inconspicuous pore like papillae on head or conspicuous papillae where lateral most papillae near nostrils form a continuous line to papillae on lateral edge of frontal bones).

Description:— Milyeringa brooksi are small (<40 mm SL), unpigmented, eyeless stygobitic fish ( Fig. 2 , 3 ). Comparative morphometric features are listed in Table 2. Head: Head large (about 40% of SL), broad (area posterior to cheeks widest part of animal) and nearly flat. Eyes absent, with no remnants of a lens (as determined by x-rays) or other features related to vision. Mouth large (about 45% of HL) curved ventrally and posteriorly at 45° from dorsal aspect of head. Lower jaw protrudes slightly anterior to upper jaw. Anterior nostril tubular immediately dorsal to upper lip. Posterior nostril oval, somewhat tube shaped, larger than anterior nostril with excess skin forming flap. Toungue flat and blunt anteriorly. Teeth unicuspid and strongly recurved. Teeth set in three to five irregular rows from most anterior edge to angle of mouth. Teeth on inner (medial) side of jaws larger than those on anterior edge with largest teeth near angle of mouth. Gills: Gill cover large (about 40% of HL) branchiostegal membranes almost completely exposed. Lower arm of gill arch very elongate (making counts difficult without dissection). Ten to 12 gill rakers present on ceratobranchial of first gill arch. Gill rakers long and thin, small denticles present on medial side of rakers. Rakers on medial edge of gill arch short, covered dorsally with denticles. Gill filaments thick and short (about same length as longest rakers). Sensory papillae: One line of papillae loosely follows shape of anterior edge of opercle and preopercle, opercular row of papillae continues on ventral side of head around gular region. Preopercular row of papillae are tightly bound to edge of preopercule in comparison to those on opercule. [These opercular rows are similar in location to nueromast rows ot, os, oi of Wongrat and Miller’s (1991) study of Perccottus glenii and Bostrychus urophthalmus .] Four parallel rows of sensory papillae present on cheek, second row from top is longest extending to papillae on preoperculum [this row is similar to Wongrat and Miller’s (1991) nueromast row b with innervation from the ramus buccalis in Perccottus glenii ], other rows less dense and do not reach preopercular row. Largest papillae on head present around lips; these sensory papillae follow closely the outline of lips on all sides of mouth including ventrally. Few papillae on dorsal aspect of head, those present are concentrated posteriorly and anteriorly. Two rows of papillae present on each side of posterior edge of head. Rows consist of about five papillae near lateral and medial edge of frontal bones. Four rows of papillae between left and right nostril (two rows on each side of midline) running in parallel [similar in their location to the rows in Perccottus glenii that are innervated by the truncus supraorbitalis in that species Wongrat and Miller (1991)]. These rows of papillae extend only slightly past posterior nostril on each side of head. Papillae on body less conspicuous than those on head. No lateral line. Ten to 12 vertical lines of papillae present on body. First vertical line of sensory papillae on body (most anterior column) found dorsal to pectoral-fin base. Most posterior line is on caudal-fin base just posterior to caudal flexure (with about eight large papillae). Posterior-most line has largest sensory papillae on body. Largest papillae along body concentrated near midline of each vertical line and become smaller dorsally and ventrally. All lines of papillae on body and head are composed of single well-defined papillae in a row. In some individuals papillae are more conspicuous on one side of body than the other. Body: Body is slim relative to head becoming thinner and shorter posteriorly. A sulcus is present on dorsal surface of body between posterior end of head and first dorsal fin-base. There are less pronounced grooves between pelvic and anal fins, and along the midline of caudal peduncle. Twenty-four total vertebra (10 precaudal + 14 caudal, including last ½ centrum). Paired intermuscular elements are present suspended above precaudal centra 3 to 6. Scales: Body covered in thin, deeply embedded, transparent cycloid scales. Head naked and chest (region anterior to pelvic fins) generally naked (one paratype had chest scales). Fins: Two separate dorsal fins, first is short (less than 1/3 of height of second) with four thin and weak spines, second with nine unbranched but segmented rays. There are four rays in the pelvic fin, nine in the anal fin, 18 segmented unbranched principal caudal-fin rays and 14 pectoral-fin rays. Second dorsal, pectoral, pelvic, anal, and caudal fins all have elongated trailing rays to varying degrees. Vertical from anterior portion of anal-fin base reaches between third and forth soft ray of second dorsal fin. Posterior edge of anal-fin base is slightly posterior to vertical from termination of second dorsal-fin base.

Color: In life, M. brooksi is depigmented, appearing almost uniformly pinkish white. Pink color is most conspicuous where blood is concentrated, such as over gills as seen through gill cover. Coloration uniform off-white cream in preservative. Area above brain transparent and brain case appears purplish in life and dark grey in preservative. Fins and gill covers are hyaline.

Etymology:— Named for Darren Brooks whose knowledge of these fishes and the caves that house them is unsurpassed, and whose efforts to help conserve these unique ecosystems have been invaluable.

Distribution:— This species is found in the karst systems and underground water channels from Tulki Well (22° 06’S. 113° 54’E) in the north, to an area near the abandoned Ningaloo tower (22° 42’S 113° 40’E; also called Point Cloates Lighthouse on local maps) in the southwestern portion of the Cape Range of Australia. The type locality is Pilgonaman Well ( Fig. 5 ), which along with Tulki Well is located within Cape Range National Park. Jarvis Well, which is now filled in, and the Ningaloo Tower location are found outside of the Cape Range National Park. The distribution of these fishes spans approximately 75km along Yardie Creek road on the southeastern side of the North West Cape. The range likely spans underground interconnected waterways that incorporate these surface openings (wells and caves) separated from those belonging to M. veritas in the northern portion of the North West Cape. The specimens from Tulki Well and the Ningaloo tower (see Materials Examined) are not part of the type series and were not sampled in the molecular study; however, these formalin-fixed specimens exhibit the diagnostic morphological features of M. brooksi .

Figures

FIGURE 2. Holotype of Milyeringa brooksi, WAM P28330.

FIGURE 3. Illustration of the holotype of Milyeringa brooksi, WAM P28330 showing expanded fins, selected scales and sensory papillae. Illustration by Jill Meredith Dowling.

FIGURE 4. Close-up view of vertical lines of sensory papillae on the caudal peduncle in M. brooksi. Image shows the last five rows of papillae on the body of the holotype.

FIGURE 5. (A) The author and Darren Brooks at the type locality of Milyeringa brooksi, Pilgonaman Well, (B) Mr. Brooks at the bottom of the well approximately 10 meters below the surface.