Schroederichthys saurisqualus Soto, 2001

Soares, Karla D. A. & Zanini, Flávia, 2023, Redescription and anatomical investigation of Schroederichthys maculatus Springer, 1966 and S. saurisqualus Soto, 2001 with comments on their systematics (Chondrichthyes: Carcharhiniformes: Atelomycteridae), Zoologischer Anzeiger 302, pp. 224-238 : 230-235

3.1.2. Schroederichthys saurisqualus Soto, 2001

( Figs. 4 , 5 , 6 , 7 , 8 and 10 , 112B, 13C, D; Tabs. 2 , 3 , 6 , 7 ).

3.1.3. Common names: lizard catshark (English), tubarao-lagartixa ˜ (Portuguese)

Schroederichthys saurisqualus Soto, 2001: 37–52 , Figs. 1–15 (original description, type locality: Santa Catarina, Brazil); Compagno et al., 2005:245, pl. 41 (checklist); Ebert et al., 2013:376 (checklist); Weigmann 2016:879 (checklist); Gomes et al., 2019:240, fig. 138 (catalogue, Rio de Janeiro, Brazil); Soares 2020: 1–17, Figs. 7c and 16c (clasper morphology); Soares and de Carvalho, 2020:379 (phylogeny).

Holotype. MOVI 05949 , male, 582 mm TL (Santa Catarina, Brazil, 27 ◦ 30 ′ 16 ′′ S 47 ◦ 36 ′ 03 ′′ W, 122–130 m depth).

Material examined. MZUSP 52903 , male, 406.7 mm TL (no locality data); MZUSP 86545 , female, 328.5 mm TL, female, 293.8 mm TL (no locality data); UERJ uncatalogued, male, 582.7 mm TL, adult male, 587.5 mm TL, adult male, 601.2 mm TL [D], male, 574.2 mm TL, male, 532 mm TL, male, 607.6 mm TL, female, 606.2 mm TL (Santos, Sao ˜ Paulo, Brazil) ; UERJ uncatalogued, adult male, 597.5 mm TL, female, 626.9 mm TL [D] ( Ilha de Moleque do Sul , Santa Catarina, Brazil) ; UERJ uncatalogued, male, 542.4 mm TL ( Ilha de Bom Abrigo , S˜ao Paulo, Brazil); UERJ 1857 , male, adult 597 mm TL ( Paranagu´a , Paran´a, Brazil); UERJ 1568 , male, 587 mm TL, male, 578 mm TL (Paran´a, Brazil); UERJ 1887 , female, 568 mm TL (no locality data); UERJ 1231 , male, adult 592 mm TL (no locality data); ZMH 106492 , female, 576.8 mm TL (30 ◦ 7 ′ S, 47 ◦ 58 ′ W, 520 m depth).

Diagnosis. Schroedericthys saurisqualus distinguishes from its congeners by the following combination of characters: color pattern composed by dark and light spots (vs. no dark spots in S. maculatus ; no light spots in S. tenuis ); adult males and females measuring 580 mm and 690 mm TL, respectively (vs. 530 mm and 400 mm TL in S. bivius ; 560–620 mm TL in S. chilensis ; 280 mm and 342 mm TL in S. maculatus ; 400–470 mm and 370–460 mm TL in S. tenuis ); dorsal terminal 2 cartilage absent (vs. present in S. bivius , S. maculatus and S. tenuis ); anterior nasal flaps lobelike with posterior margins deeply notched (vs. nasal flaps triangular and slightly notched in S. chilensis and S. maculatus ).

External morphology. Body slender and cylindrical, tapering considerably posterior to cloaca ( Fig. 4 ). Prepectoral length 0.4–0.5 times the prepelvic length ( Table 2 ). Trunk shorter than tail region; vent-caudal length 1.9–2.1 times vent-caudal length. Pectoral-pelvic space 0.7–0.9 times the pelvic-anal space. Interdorsal space 1.3–1.9 times the dorsal-caudal space. No interdorsal, postdorsal or postanal ridges. Head narrow and depressed; head length 1.5–1.6 times head width. Snout relatively short, preoral length 0.4–0.6 times mouth width and 1.1–1.8 times smaller than preorbital length. Prenasal length 0.8–1.1 times internarial space; preorbital length 0.7–1.0 times interorbital space.

Eye large and slitlike, eye length 2.1–2.5 times its height and 3.9–4.2 times smaller than head length ( Fig. 5 ). Eye dorsolateral on head, with lower edge medial to horizontal head rim in dorsal view; subocular ridge strong. Nictitating lower eyelid of rudimentary type, with shallow subocular pouch and secondary lower eyelid free from upper eyelid. Spiracle close behind but well separated from eye, dorsolaterally on head and somewhat lower than level of eye notch. Spiracle diameter goes 4.7–7.2 times in eye length and 6–11.2 times in interorbital distance. First two gill openings about equally wide; first one twice as long as fifth. All gill openings slightly concave and not elevated on the dorsolateral surface of head.

Nostril with broad incurrent aperture, without nasoral groove or nasal barbel, and small and oval excurrent aperture ( Fig. 5 ). Anterior nasal flap divided in two portions, lobelike and elongated laterally and subrectangular medially, partially covering the excurrent aperture but not the posterior nasal flap, and distant from mouth. Mesonarial ridge distinct but not exceeding the posterior edge of the anterior nasal flap. Posterior nasal flap rectangular, situated on the posterior edge of the excurrent aperture. Mesonarial superior and inferior flaps conical and similar in size to the posterior nasal flap. Internarial distance 1.4–2.4 times smaller than interorbital distance.

Mouth arched, wider than long, its length 1.4–2.2 times the mouth width ( Fig. 5 ). Labial furrows present and discontinuous (sensu Soares and de Carvalho, 2020); upper furrow slightly greater than the lower one. Lower labial furrow slender than the upper one, 2.8–4 times smaller than mouth width. Tongue flat and rounded, light-colored, with oral papillae hardly detectable.

Pectoral base 0.6–0.8 times mouth width. Pectoral anterior margin 2.5–3.2 times its base and 1.4–1.7 times the posterior margin. Pelvic fin trapezoidal; pelvic anterior margin 0.9–1.3 times the posterior margin and 1–1.6 times the pelvic base. Pelvic inner margins not fused in males and claspers surpassing the pelvic inner margin in adult males. Clasper inner length 1.0–2.5 times its outer length and 4.6–5.8 times its base width.

First dorsal fin triangular, with nearly straight anterior margin, rounded apex and angular free rear tip. First dorsal fin origin slightly posterior to the insertion of pelvic fin. Anterior margin 1.1–2.2 times first dorsal fin base; first dorsal fin height similar in size to its base. Second dorsal fin somewhat similar in size to the first, slightly smaller in some specimens (Figs.). Second dorsal fin origin opposite to the posterior third of anal base and insertion opposite to the posterior end of the anal fin. Anterior margin 1.3–1.7 times base of second dorsal fin; second dorsal base 1.1–1.6 times its height and 0.4 times the dorsal-caudal distance.

Anal fin low, subtriangular, apically narrow, and not falcate; anal fin base 1.2–1.5 times the second dorsal fin base. Anal fin anterior margin nearly straight, apex narrowly rounded, free rear tip acutely pointed, posterior margin concave, and inner margin straight. Anal fin base 0.3–0.4 times the interdorsal distance and 0.6–0.7 times the dorsal-caudal distance. Anal anterior margin 0.8–1.1 times the posterior margin; anal fin height 0.2–0.6 times its base.

Caudal fin narrow-lobed and asymmetrical, lower caudal fin not produced as a lobe. Dorsal caudal lobe 2–2.8 times larger than preventral lobe; subterminal caudal margin 0.8–1.6 times the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Coloration. Dorsolateral surfaces dark grey to dark brown covered by dark spots smaller than the spiracle and randomly distributed throughout the body; light spots present only within intersaddles or less numerous within saddles. Pectoral, caudal and dorsal fins with dark spots up to their distal margins; pelvic and anal fins with no spots. Ten to twelve darker brown primary saddles without definite edging; 4 saddles anterior to the first dorsal fin and 6–8 posterior to it. Secondary saddles situated posteriorly to the first dorsal fin more conspicuous than in anterior regions. Saddles and spots surpassing the lateral line ventrally only anterior to the first dorsal fin. Belly and ventral surface cream and uniform, with no spots.

Dermal denticles. Lateral trunk denticles with flat and teardropshaped crowns, 0.9–1.3 times longer than wide; cusplets absent ( Fig. 6 ). Ectodermal pits extending up to the half-length of crown in dermal denticles above the pectoral and restricted to the anterior margin in denticles of more posterior regions. Crown with six to eight prominent ridges extending its entire length onto principal cusp in anterior regions and not surpassing the half-length of crown in posterior regions.

Teeth. Monognathic heterodonty gradual and dignathic heterodonty weak ( Figs. 7 and 8 ). Upper teeth row and series distributed in an alternated pattern and lower teeth alternate from symphysial to anteriors, then diagonal file from latero-posteriors to commissurals; adjacent teeth along series independently arranged. Sexual heterondonty observed; characters of female specimens are described first and males within parentheses, when different.

Tooth counts (28–31)-1-(28–33)/(18–24)-1-(18–25). Symphyseal teeth similar in length to parasymphyseal (vs. smaller), with a principal cusp flanked by two cusplets at each side (vs. one cusplet). Proximal cusplets half to two thirds the height of principal cusp and marginal ones half the height of the adjacent cusplet ( Table 6 ). Crown base straight ( Table 7 ). Protuberances defined on the crown base in females (vs. undefined). Striae extending through almost the entire crown and more prominent in females. Ectodermal pits restricted to the crown base.

Parasymphyseal teeth smaller than anteriors. Lower teeth with one to three cusplets on each side; proximal cusplets half the height of the principal cusp, medial ones half the height of the proximals and marginal cusplets half the height of adjacent medial cusplet (vs. cusplets poorly developed); crown base varying from straight to concave. Protuberances on the crown base (vs. undefined); striae and ectodermal pits restricted to the crown base. Upper teeth with a principal cusp flanked by two cusplets on each side (vs. one cusplet). Proximal cusplet half the height of principal cusp and marginal ones half the height of adjacent cusplet. Crown base straight. Protuberances on the crown base; striae extending through the entire crown (vs. half the crown). Ectodermal pits restricted to the crown base.

Anterior teeth in lower jaw with a principal cusp flanked by three cusplets on each side (vs. two cusplets). Proximal cusplet half the height of principal cusp, medial cusplet half the height of the proximal cusplet; marginal cusplet half the height of adjacent medial cusplet. Crown base varying from straight to concave. Protuberances on the crown base; striae restricted to the crown base (vs. only at the central portion). Ectodermal pits restricted to the crown base (vs. absent). Upper anterior teeth with three or four cusplets (vs. two in males). Proximal cusplet half the height of the principal cusp; marginal cusplet half the height of adjacent proximal cusplet. Principal cusp slightly oblique toward the commissure. Crown base straight (vs. slightly concave). Protuberances on the crown base; striae extending to half the crown. Ectodermal pits restricted to the crown base (vs. only at the lateral portion).

Lateroposterior teeth become smaller distally, except upper teeth in male that are smaller than anteriors. Lower teeth similar to anterior in females, flanked by two or three cusplets on each side (vs. two cusplets). Proximal cusplet varying from half to two thirds the height of principal cusp; medial cusplet half to two third the height of adjacent proximal cusplet; marginal cusplets one third to half the height of adjacent cusplet. Principal cusp erect or slightly oblique toward the commissure. Crown base slightly concave. Protuberances on the crown base (vs. less defined); striae restricted to the crown base and more prominent in females. Ectodermal pits restricted to the crown base (vs. only at the lateral portion). Upper lateroposterior teeth with four or five cusplets (vs. three or four). Proximal cusplet half the height of principal cusp; medial cusplets half to two-third the height of adjacent proximal cusplet; marginal cusplets one-third to half the height of adjacent cusplet. Principal cusp slightly oblique toward the commissure. Crown base straight. Protuberances on the crown base; striae extending to half the crown (vs. less prominent). Ectodermal pits restricted to the crown base (vs. only at the lateral portion).

Comissural teeth smaller than lateroposteriors, multicuspidate with five to nine cuspids. Lower teeth cusplets half to two-third the height of adjacent cusplet. In males, principal cusp erect or slightly oblique toward the commissure. Crown base varying from straight to slightly concave. Protuberances on the crown base; striae extending through almost the entire crown (vs. restricted to the crown base). Ectodermal pits restricted to the crown base (vs. only at the lateral portion). Upper teeth with not well defined cusplets (vs. cusplets half to two-third the height of adjacent cusplet). Principal cusp slightly oblique toward the commissure. Crown base straight. Protuberances on the crown base; striae extending through almost the entire crown, and more numerous than lower teeth (vs. extending to half the crown). Ectodermal pits restricted to the crown base (vs. only at the lateral portion).

Figures

Fig. 4. External morphology of Schroederichthys saurisqualus, UERJ uncatalogued, female, 606.2 mm TL; external morphology. A, lateral and B, ventral views. Scale bar =10 cm.

Fig. 5. Close-ups of Schroederichthys saurisqualus. A, ventral view of head, UERJ uncatalogued, female, 606.2 mm TL; B, ventral view of head, UERJ uncatalogued, male, 580 mm TL; C, lateral view of head, UERJ uncatalogued, female, 606.2 mm TL. Scale bar =10 cm.

Fig. 6. Dermal denticles of Schroederichthys saurisqualus, A–C, UERJ uncatalogued, female, 606.2 mm TL; D–F, UERJ uncatalogued, male, 580 mm TL. A, D, region above pectoral fin base; B, E, region below first dorsal fin origin; C, F, region below second dorsal fin insertion. Scale bar =100 um.

Fig. 7. Teeth of a female specimen of Schroederichthys saurisqualus, UERJ uncatalogued, female, 564 mm TL. Scale bars =100 um. Abbreviations: a, anterior; c, commissural; lp, lateroposterior; ps, parassymphysial; s, sympshysial.

Fig. 8. Teeth of a male specimen of Schroederichthys saurisqualus, UERJ uncatalogued, male, 580 mm TL. Scale bars =100 um. Abbreviations: a, anterior; c, commissural; lp, lateroposterior; ps, parassymphysial; s, sympshysial.

Fig. 10. Neurocranium of Schroederichthys saurisqualus, UERJ uncatalogued, male, 580 mm TL. A, dorsal, B, ventral, C, lateral views. Abbreviations: Scale bar = 10 mm.

Fig. 1. Schematic drawing of tooth measurements.

Fig. 2. Holotype of Schroederichthys maculatus, USNM 185556, male, 328 mm TL; external morphology. A, lateral and B, ventral views. Scale bar =10 cm.

Fig. 3. Teeth of Schroederichthys maculatus, USNM 187690, male, 325 mm TL. Scale bar =100 um.

Fig. 9. Neurocranium of Schroederichthys maculatus, USNM 187690, male, 325 mm TL. A, dorsal, B, ventral, C, lateral views. Scale bar =10 mm.

Fig. 11. Dorsal view of the neurocranium of Schroederichthys saurisqualus, UERJ. A, UERJ uncatalogued, female, 564 mm TL. B, UERJ uncatalogued, male, 580 mm TL. Scale bar =10 mm.

Fig. 12. Ventral view of jaws. A, Schroederichthys maculatus, USNM 187690, male, 325 mm TL; B, Schroederichthys saurisqualus, UERJ uncatalogued, male, 580 mm TL. Scale bar =20 mm.

Fig. 13. Hyoid and gill arches. A, B, Schroederichthys maculatus, USNM 187690, male, 325 mm TL; C, D, Schroederichthys saurisqualus, UERJ uncatalogued, male, 580 mm TL. A-C, dorsal view; B-D, ventral view. Scale bar =10 mm.

Fig. 14. Parsymphyseal teeth diferences between Schroederichthys maculatus, represented by circles, and S. saurisqualus represented by triangles. Abbreviations: BCW, basal crown width; CH, crown height; DPCPH, distal proximal cusplet height; MCW, mid-crown width; MPCPH, mesial proximal cusplet height.

Fig. 15. Anterior teeth diferences between Schroederichthys maculatus, represented by circles, and S. saurisqualus represented by triangles. Abbreviations: BCW, basal crown width; CH, crown height; DPCPH, distal proximal cusplet height; MCW, mid-crown width; MPCPH, mesial proximal cusplet height.

Fig. 16. Comissural teeth diferences between Schroederichthys maculatus, represented by circles, and S. saurisqualus represented by triangles. Abbreviations: BCW, basal crown width; CH, crown height; DPCPH, distal proximal cusplet height; MCW, mid-crown width; MPCPH, mesial proximal cusplet height.