Indobatis ori
Creators: name: Weigmann, Simon
name: Stehmann, Matthias F. W.
name: Thiel, Ralf
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Elasmobranchii
Rajiformes
Anacanthobatidae
Indobatis
Indobatis ori

description: Indobatis ori (Wallace, 1967)
(Black Legskate)
Figs. 2–24, Tables 2–4
Springeria ori Wallace, 1967.
Holotype: juvenile female 206 mm TL, SAIAB (formerly RUSI) 8343 (previously O.R.I. B188); paratype: juvenile female 145 mm TL, SAIAB (formerly RUSI) 8344 (previously O.R.I. B187).
Synonyms: Anacanthobatis (Anacanthobatis?) ori of Hulley (1973); Anacanthobatis ori of Séret (1986).
Diagnosis. Type species of the new genus Indobatis. A medium-sized southwestern Indian Ocean anacanthobatid species growing to about 429 mm TL. Disc 0.9–1.1 times as wide as long and with rounded outer corners, extremely depressed pear-shaped to broadly inverse heart-shaped (in adult male). Snout angle 85–106°, larger in juveniles; snout terminally expanded as a rostral lobe that is 9–12% of preorbital snout length; juveniles additionally with a short, thin rostral filament. Interorbital distance narrow, 2–3% of TL. Inner margin of posterior pelvic lobe fused along its entire length to root of tail. Tail length from mid-vent about equal to body length from tip of rostral lobe to mid-vent in adults, but 1.5 times body length in juveniles. Upper and lower surfaces of disc and tail entirely naked except for two longitudinal rows of alar thorns in adult male. Tail with two lateral rows of fleshy, tubular papillae. Upper and lower surfaces dark grayish-brown, but ventral surface somewhat darker. Upper jaw tooth rows 18–26, monospondylous vertebral centra 25–29. Scapulocoracoid subrectangular, with rear corner sharply marked; large oval anterior fenestra without anterior bridge, one very large oval postdorsal and five minute to small postventral fenestrae. Pelvic girdle with massive ischiopubic bar with straight to weakly concave anterior and deeply concave posterior contour; prepelvic processes very long and inclined outwards, their length from axis of pelvic girdle maximal width 3.9–5.3 times median thickness of ischiopubic bar.
Description (Figs. 2–24). Detailed morphometrics and meristics given in Table 2. Where relevant, ratios are based on horizontal measurements unless otherwise stated.
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External morphology (Figs. 2–15): Disc extremely depressed pear-shaped in juveniles and adult female, but broadly inverse heart-shaped in adult male; anterior margins almost straight to slightly convex, outer and inner pectoral corners broadly rounded, posterior margins evenly convex, pectoral axils partially fused to outer margin of posterior pelvic lobes in adult male, but almost entirely fused in all other specimens; disc width 0.9–1.1 times disc length, disc length 2.5–3.0 times preorbital snout length and 2.4–2.7 times preoral snout length; axis of maximal disc width at 33 % of TL in adults and 26–30% of TL in juveniles (Figs. 2–7). Dorsal head length 25–26% of TL in adults and 20–22% of TL in juveniles (Figs. 8–9). Snout long and pointed, gradually tapering to the rostral lobe that is not marked off in adult male, but snout tip marked off as subtriangular rostral lobe in adult female and juveniles; rostral lobe 9–12% of preorbital snout length; a thin rostral filament attached to the rostral lobe in juveniles (Fig. 10), but absent in both adults; snout pointed at about 85° in adults and at about 97–106° in juveniles; preorbital snout length 5.2–6.9 times interorbital width; preorbital snout length 2.3–2.7 times in disc width in adults and 2.8–3.2 times in juveniles. Eyes and orbits small and not elevated above level of cranium, orbits not well-defined, their estimated horizontal diameter 0.7–0.9 times interorbital width and 10–11% (in adults) or 12–16% (in juveniles) of preorbital snout length; interorbital width narrow, 2–3% of TL; spiracles small and circular, close posterior to eyes, their length 35–44% of orbit horizontal diameter; interspiracular space 1.7–1.9 times interorbital width; 7–9 pseudobranchial folds in each spiracle. Tail cord-like, only slightly tapering towards its tip, length from mid-vent to tip about equal to body length from tip of rostral lobe to mid-vent in adults, but 1.5 times body length in juveniles, tail length 51% of TL in adults, but 59–60% of TL in juveniles; no dorsal fins; no lateral tail folds; tail width to height at level of pelvic tips 1.9 in adult male and 1.1–1.5 in adult female and juveniles; tail oval, trapezoid or quadratic in cross section, slightly compressed posterior to origin of band-like caudal fin; epichordal caudal lobe confluent around tail tip with shorter hypochordal lobe.
Ventral head length 31–32% (in adults) or 25–27% (in juveniles) of TL and 7.0–8.3 times internarial width (Figs. 11–12). Preoral snout length 21–24% (in adults) or 17–19% (in juveniles) of TL and 3.9–5.0 times mouth width. Mouth cavity with papillose integument, mouth small, jaws straight; mouth width 14–17% of ventral head length and 1.0–1.3 times internarial space; 18–26 tooth rows in upper and 16–22 in lower jaws, set in quincunx pavement pattern; individual tooth with low, subcircular to rhombic base, flat crown, and with very short and stout conical cusp in juveniles and adult female, but teeth with longer, stout, and conical cusp in adult male (Figs. 13– 14). Gill openings very small, length of first gill slit 0.4–0.8% of TL; distance between fifth gill slits 56–62% of distance between first gill slits, the latter 2.7–3.1 times internarial space. Anterior nasal flaps low and fleshy, edges weakly serrated and undulated, terminal part with short fringes; nasal curtain with papillae on underside, oriented in longitudinal direction and laterally only weakly protruding, outer edges distinctly angled at about 90°, apices angular, short and nearly transversal posterior margins set with short and stout, fleshy fringes; isthmus deep arc-shaped (Figs. 13–14). Pelvic-fin anterior lobes slender and leg-like, slightly broadened near tip, the diagonal terminal edges with three jags with rounded tips; anterior lobes separated from posterior ones and 1.0 (in adults and the largest juvenile specimen ZMH 25928) or 1.1–1.4 (in the other juveniles) times longer than posterior lobes; posterior lobes fin-like, their inner margins fused to root of tail almost along their entire length with only a short, rounded free tip.
Claspers of adult male fully developed, short, moderately slender, with a slight constriction in the stem near the terminal part; stem strong, terminal region only slightly widening, and evenly tapering to tip (Fig. 15); claspers exceeding tips of posterior pelvic lobes to about one fourth of tail length, their postcloacal length 31% of tail length.
Relatively few fleshy, tubular papillae scattered dorsally on disc, not concentrated in particular areas; a row of widely spaced papillae proceeds roughly diagonally from about level of shoulder girdle to tail and continues as more densely set lateral row along tail to nearly tail tip (Fig. 15, inset); no pores on median trunk near the vertebral column, dorsal tail pores slit-shaped. Ventrally, fields of densely arranged pores prenasally on basal half of rostrum, narrowly triangular fields of pores from nasal region outwards over half the distance to disc margins, a single transversal row of densely set, distinct pores internasally between anterior nasal flaps (Figs. 13–14).
Squamation (Fig. 16): Upper and lower surfaces of disc and tail entirely naked except for the alar thorns in adult male ZMH 25926; alar thorns sharp, claw-like, permanently erect, located in individual, transversal dermal pockets, and arranged in very short field of two longitudinal and four to six transverse rows that is located posterior to level of maximal disc width (Fig. 16).
Coloration (Figs. 2–7): Upper disc dark grayish-brown; orbits, spiracles, and gill region including gill openings dusky. Ventral disc dark grayish-brown, slightly lighter in anterior half as well as along midbody, generally somewhat darker than dorsal surface, especially in posterior two thirds; nasal flaps and curtain light gray, underside of nasal curtain gray pigmented; mouth cavity whitish with underlying dark pigment, teeth yellowish; pelvic-fin posterior lobes dark grayish-brown like posterior ventral disc, anterior lobes distinctly lighter, especially in juveniles, in which the anterior lobes are almost totally ocher. Claspers of adult male brown. Alar thorns of adult male distinctly marked off creamy white in light gray pockets. Pores and tubular papillae marked off light gray. Tail dorsally and ventrally dark grayish-brown anteriorly, fading to light gray in terminal part, with nearly transparent caudal fin.
Clasper external morphology (Fig. 17): External pseudosiphon-like cavity (‘ps’) present at outer margin of dorsal lobe, bordered by sharply serrated pecten (pc). The cavity is named ‘ps’ instead of a real pseudosiphon (ps) as it is related to the dorsal terminal 2 instead of the dorsal terminal 1 cartilage. Inner dorsal lobe without clefts, but with a slit (sl) spanned between flag and sentinel, flag (fg) situated above axial cartilage. Inner ventral lobe with very long and broad shield (sh) along proximal two thirds of outer margin, with short free cartilaginous tip at proximal end and narrow outer edge of free cartilage that is finely serrated in proximal half, inner surface of sh covered by smooth integument without lamination, proximal tip of sh forming eperon (ep); a very long fan-shaped pent (pe) with prominent lamellae parallel to sh, expanding from level of ep along inner proximal half of lobe; two free cartilaginous tips in distal half of lobe are sentinel (st) as a slightly inwards bent, narrow, and sharp cartilaginous tip, bordering two sentinas (se), with one spanned to the outer margin of lobe and the smaller one spanned to the spike, and spike (sk) that is spoon-shaped, broader, and slightly shorter than st.
Clasper skeleton (Figs. 18–21): Beta cartilage on head of axial cartilage (ax) moderately large, its length about one fourth of dorsal marginal cartilage length (Fig. 18). Narrowly plate-shaped dorsal marginal cartilage (dm) extending along proximal two thirds of clasper, its proximal end evenly narrowing and ending more distally than head of ax; dm outer distal edge curved inwards and with an elongated, hook-like, pointed process (Fig. 19). Dorsal terminal 1 cartilage (dt1) moderately small and subrectangular, with narrowly pointed distal tip, atypically positioned distinctly anterior to the glans clasper, curving around ax and edges of dorsal and ventral marginal cartilages (Figs. 18, 19). Dorsal terminal 2 cartilage (dt2) subtriangular, narrow proximal end connected to dm and wide distal edge connected to dorsal terminal 3 cartilage, outer edge sharply, deeply, and coarsely serrated, forming pc externally. Dorsal terminal 3 cartilage (dt3) pistol-shaped, with subrectangular proximal section and bluntly pointed distal tip. Ventral marginal cartilage (vm) narrowly plate-shaped, distally somewhat spatula-like widened, extending along proximal two thirds of clasper, its proximal end with a triangular and pointed tip falling short of dm tip. Long ventral terminal cartilage (vt, Fig. 20) bifid with the subtriangular, plate-like, and long main part forming ep and sh externally; the proximal process diverges from the main part as a long, slender strap curving around the accessory terminal cartilages and dt3 in the median part of the glans clasper. Accessory terminal 1 cartilage (at1, Fig. 21) rod-shaped, its head embedded in the cavity of baseball-glove-shaped head of accessory terminal 2 and not connected to vm, its distal tip spatulate, forming st externally. Accessory terminal 2 cartilage (at2, Fig. 21) narrowly spoon-shaped at head and with spatulate, slender distal section; at2 proximally connected to vm and its distal tip forming sk externally.
Cranium: The cranium is only poorly calcified even in the adult specimens. Therefore, morphometrics could not be taken by means of radiographs. The cranium of a juvenile specimen of Anacanthobatis ori was described and figured by Séret (1986).
Scapulocoracoid (Fig. 22): Scapulocoracoid shown by drawing of the dissected left scapulocoracoid of adult male ZMH 25926, morphometrics presented in Table 3. Dissected element long, subrectangular, maximal length 1.8 times maximal height; height at sharply marked rear corner 77% of maximal height; post-mesocondyle-length 2.4 times as long as pre-mesocondyle-length; postdorsal margin sloping strongly concavely from pointed rear corner to metacondyle; anterior bridge absent; broadly oval, large anterior fenestra (af) oriented somewhat diagonally, only slightly higher than long, its length 21.4% of scapulocoracoid maximal length; very large, long, and elliptical postdorsal fenestra (pdf) oriented somewhat diagonally, 1.7 times longer than high, its length 38.3% of scapulocoracoid maximal length; four minute and one small postventral fenestrae (pvf), subcircular to narrowly elliptical, the small pvf near the metacondyle 1.6 times longer than high and its length 6.6% of scapulocoracoid maximal length.
Pelvic girdle (Fig. 23): Pelvic girdle shown by radiographs of adult male ZMH 25926 and adult female ZMH 25927, Table 4 provides pelvic morphometrics measured from radiographs. Pelvic girdle U-shaped as typical in the Anacanthobatidae, with the iliac regions considerably more massive than in most Rajidae and the prepelvic processes very elongated; ischiopubic bar massive and thick, anterior contour nearly straight in females, but weakly concave in males, posterior contour a broad, deep trapezoid in females, but a narrow, elliptical, deep trapezoid in males; iliac regions enlarged and with a single, large obturatorial foramen on each side; prepelvic processes long and slender, their length from axis of pelvic girdle maximal width 79.1–88.0% of maximal width of pelvic girdle, their bluntly rounded tips curving outwards; contrary to the strongly developed prepelvic processes, the iliac processes are short, slenderly conical, and oriented completely anteromedially. Axis of pelvic girdle maximal width slightly posterior to rear contour of ischiopubic bar in adults and juvenile females, but level with or slightly anterior to rear contour in juvenile males. Proportionally, the pelvic girdle of adult females is apparently wider than that of adult males as the pelvic girdle maximal width is 7.0% of TL in adult female ZMH 25927, but 6.3% of TL in adult male ZMH 25926; no clear sexual dimorphism in the six juveniles with pelvic girdle maximal widths from 5.4–6.2% of TL. In relation to the shoulder girdle maximal width, the pelvic girdle is also slightly wider in adult female with pelvic girdle maximal width 50.0% of shoulder girdle width vs. 47.7% in adult male; again no sexual differences in the six juveniles with maximal pelvic girdle width 46.6–56.1% of shoulder girdle width. Morphologically, the sexual dimorphism of pelvic girdle is rather weak even in adult specimens.
Skeletal meristics (from radiographs, Table 2, Fig. 24): Trunk vertebrae (Vtr): 25–26 in adults, 26–28 in juveniles; precaudal tail vertebrae (approximately): 145–160; caudal tail vertebrae (approximately): 30–40; total tail vertebrae (approximately): 175–195; pectoral radials, left/right: 68–72/68–73; pelvic radials: 3+9–3+10 in males, 3+12–3+13 in females.
Size: A medium-sized legskate species reaching about 429 mm TL.
Distribution (Fig. 1): The eight examined specimens were caught in the western Indian Ocean off South Mozambique in 1230–1260 m depth. The species is also known from off Central Mozambique in 1509–1600 m depth (holotype and paratype) and from off Northwest Madagascar in 1000–1725 m depth (two specimens described by Séret, 1986).
Remarks. In radiographs, the tips of the prepelvic processes seem to be bifurcated at least in the adult male ZMH 25926 as well as in several of the comparative specimens of other species. The partial dissection of comparative specimen Anacanthobatis longirostris ZMH 119918, male 422 mm TL, indicates that the anterior prepelvic processes are not really bifurcated, but obviously the central parts of the tips are only weakly calcified and, therefore, only the stronger calcified outer edges are visible on radiographs which simulates a bifurcation. The seeming bifurcation is most obvious in comparative specimens of A. marmorata (Fig. 25, D; Fig. 26, B) and Sinobatis borneensis (Chan, 1965b) (Fig. 25, F; Fig. 26, C). In proportion to the maximal width of pelvic girdle in males, Indobatis ori has distinctly shorter prepelvic processes compared to A. marmorata, shorter processes than A. americana, A. longirostris, S. bulbicauda Last & Séret, 2008, and S. melanosoma, processes of about equal length as A. folirostris, S. caerulea Last & Séret, 2008, and S. filicauda Last & Séret, 2008, and longer processes than S. borneensis (Fig. 25). However, in contrast to all other examined anacanthobatid species, the prepelvic processes of I. ori are stronger bent outwards (Fig. 25).
There are numerous morphometric and meristic differences between the adult and the juvenile specimens that might be of ontogenetic nature. 1) the axis of maximal disc width is at 33 % of TL in adults, but at 26–30% of TL in juveniles, 2) the dorsal head length is 25–26% of TL in adults, but 20–22% of TL in juveniles, 3) a thin rostral filament is attached to the rostral lobe in juveniles, but absent in both adults, 4) the snout is pointed at about 85° in adults, but at about 97–106° in juveniles, 5) the preorbital snout length is 2.3–2.7 times in disc width in adults, but 2.8–3.2 times in disc width in juveniles, 6) the estimated orbit horizontal diameter is 10–11% (in adults) or 12–16% (in juveniles) of the preorbital snout length, 7) the distance from mid-vent to tail tip is about equal to the body length from tip of rostral lobe to mid-vent in adults, but 1.5 times body length in juveniles, 8) the tail length is 51% of TL in adults, but 59–60% of TL in juveniles, 9) the ventral head length is 31–32% (in adults) or 25–27% (in juveniles) of TL, 10) the preoral snout length is 21–24% (in adults) or 17–19% (in juveniles) of TL, 11) the pelvic-fin anterior lobes are 1.0 (in adults and the largest juvenile specimen ZMH 25928) or 1.1–1.4 (in the other juveniles) times larger than the posterior lobes, 12) the number of trunk vertebrae is 25–26 in adults, but 26–28 in juveniles.
Furthermore, there are several differences that might be indicative of sexual dimorphism. 1) the disc is extremely depressed pear-shaped in the adult female and the juveniles, but broadly heart-shaped in the adult male, 2) the pectoral axils are partially fused to the outer margin of the posterior pelvic lobes in adult male, but almost entirely fused in adult female and juveniles, 3) the snout is gradually tapering to the rostral lobe that is not marked off in adult male, but the snout tip is marked off as subtriangular rostral lobe in adult female and juveniles, 4) the ratio tail width to height at level of pelvic tips is 1.9 in adult male, but 1.1–1.5 in adult female and juveniles, 5) the teeth are flat, with very short and stout conical cusp in adult female and juveniles, but with longer, stout, and conical cusp in adult male, 6) there are several differences in the shape and measurements of the pelvic girdle between males and females. However, the sexual dimorphism of the pelvic girdle is only weakly pronounced compared to many other anacanthobatid and most rajid species and it is detectible not only in the adult male, but also in the juvenile males, whereas it is usually pronounced only in adult males. The number of pelvic radials is lower in males than in females (3+9–3+10 vs. 3+12–3+13). According to Séret (1986), the first propterygia articulating at scapulocoracoid’s procondyles of male pectoral skeleton are divided into two shorter elements, whereas they consist of one single, longer segment in females. This sexual dimorphism was also pictured by Hulley (1973) by means of a male and a female pectoral skeleton of Anacanthobatis marmorata. This dimorphism was also detected in most of the examined Indobatis ori specimens and in all comparative specimens. However, the largest juvenile female of I. ori (ZMH 25928) shows divided first propterygia.
Strong ontogenetic and sexual dimorphism―as found here in Indobatis ori ―is typical for legskates (Last & Séret 2008).
description: Published as part of Weigmann, Simon, Stehmann, Matthias F. W. & Thiel, Ralf, 2014, Complementary redescription of Anacanthobatis ori (Wallace, 1967) and its assignment to Indobatis n. g. (Elasmobranchii, Anacanthobatidae), with comments on other legskates, pp. 101-132 in Zootaxa 3779 (2) on pages 104-119, DOI: 10.11646/zootaxa.3779.2.1, http://zenodo.org/record/4910174