Schroederichthys maculatus Springer, 1966

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 : 226-229

3.1.1. Schroederichthys maculatus Springer, 1966

( Figs. 2 and 3 , 92A, 13A, B; Tabs. 1 , 3 , 4 , 5 ).

Common name: narrowtail catshark.

Schroederichthys maculatus Springer, 1966: 605 , Fig. 4A (original description, type locality: Cape Gracias a Dios, Honduras, Caribbean Sea ); Springer 1979: 120–121, fig. 75 (taxonomic review); Compagno 1984: 353 (FAO catalogue); Compagno 1988: 107–109, fig. 13.7 (systematic account); Compagno 1999: 480 (checklist); Compagno 2003:453; Compagno et al., 2005: 245, pl. 41 (checklist); Castro 2011:33 (catalogue, North America); Ebert et al., 2013:376 (checklist); Weigmann 2016:879 (checklist); Soares 2020: 1–17, Figs. 7b and 16b (clasper morphology).

Holotype. USNM 185556 , adult male, 328 mm TL ( Cape Gracias a Dios , Honduras, 410 m depth).

Paratype. USNM 185557 , female, 335 mm TL ( Cape Gracias a Dios , Honduras, 410 m depth) .

Additional material examined. Schroederichthys maculatus . MCZ 42984 , female, 263.3 mm TL, male, 278.4 mm TL ( Honduras); UF 27958 , adult female, 342.6 mm TL, female, 320 mm TL (no locality data); UF 229707 , female, 315.6 mm TL, female, 303.3 mm TL, female, 254 mm TL, female, 295.5 mm TL (14 ◦ 54 ′ 54 ′′ N, 81 ◦ 23 ′ 12 ′′ W); USNM 187690 , female, 300.6 mm TL, adult male, 324.5 mm TL [D], male, 233.4 mm TL (14 ◦ 10 ′ N, 81 ◦ 58 ′ W); USNM 187684 , adult male, 295 mm TL, adult male, 284.1 mm TL, female, 286.3 mm TL, female, 279.7 mm TL (16 ◦ 01 ′ N, 81 ◦ 08 ′ W, 150 m depth); USNM 185557 , female, 333 mm TL (16 ◦ 391 N, 82 ◦ 29 ′ W); USNM 185556 , adult male, 321 mm TL (16 ◦ 39 ′ N, 82 ◦ 29 ′ W).

Diagnosis. Schroederichthys maculatus distinguishes from its congeners by the color pattern characterized by a tan or light-brown dorsolateral surface (vs. beige to dark brown in S. bivius , S. chilensis , S. saurisqualus and S. tenuis ); no dark spots (vs. present in S. bivius , S. chilensis , S. saurisqualus and S. tenuis ); adult males and females measuring 280 mm and 342 mm TL, respectively (vs. 530 mm and 400 mm TL in S. bivius ; 560–620 mm TL in S. chilensis ; 580 mm and 690 mm TL in S. saurisqualus ; 400–470 mm and 370–460 mm TL in S. tenuis ); ventral terminal 3 cartilage present on clasper (vs. absent in S. bivius , S. saurisqualus and S. tenuis ; unknown for S. chilensis ). The following combination of characters also helps to distinguish the species: light spots around the body (vs. absent in S. tenuis ); anterior nasal flaps triangular with posterior margins slightly notched (vs. nasal flaps lobe like and deeply notched in S. bivius , S. saurisqualus and S. tenuis ); ventral terminal 2 cartilage triangular (vs. rodlike in S. bivius , S. saurisqualus and S. tenuis ).

External morphology. Body slender and cylindrical, tapering considerably posterior to cloaca ( Fig. 2 ). Prepectoral length 1.9–2.4 times the prepelvic length ( Table 1 ). Trunk shorter than tail region; vent-caudal length 2.0–2.1 times greater than snout-vent length. Pectoral-pelvic space 1.0–1.5 times the pelvic-anal space. Interdorsal space 1.2–1.5 times the dorsal-caudal space. No interdorsal, postdorsal or postanal ridges. Head moderately narrow and depressed; head length 1.6–1.7 times head width. Snout relatively short, preoral length 1.1–1.7 times mouth width and 1.1–1.4 times smaller than preorbital length. Prenasal length 1.8 times internarial space; preorbital length 0.6–1.0 times interorbital space.

Eye large and slitlike, eye length 2.8–2.3 times its height and 4.1–4.8 times smaller than head length ( Fig. 2A and B ). 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 at the same level of eye notch. Spiracle diameter goes 3.4–7.0 times in eye length and 6.2–16.4 times in interorbital distance. First two gill openings about equally wide; first two to three times as long as fifth. All gill openings slightly concave posteriorly and not elevated on the dorsolateral surface of the head.

Nostril with broad incurrent aperture, without nasoral groove or nasal barbel, and small and oval excurrent aperture. Anterior nasal flap triangular with a medially notched posterior margin, covering the posterior nasal flap and excurrent aperture but distant from the mouth ( Fig. 2C ). 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 and corresponding to onefourth of the area of anterior nasal flap. Mesonarial superior and inferior flaps conical and similar in size to the posterior nasal flap. Internarial distance 1.3–1.5 times smaller than interorbital distance.

Mouth arched, wider than long, its length 1.7–2.9 times the mouth width ( Fig. 2C ). Labial furrows present and discontinuous (sensu Soares and de Carvalho, 2020); upper labial furrow short, 1.3–1.5 times smaller than the lower one. Lower labial furrow slender than the upper one, 3.8–6.4 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 2.5–2.8 times its base and 1.6–2.1 times the posterior margin. Pelvic fin trapezoidal; pelvic anterior margin 0.9–1.7 times the posterior margin and 0.9–1.6 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 opposite to the anterior third of the pelvic inner margin. Anterior margin 1.3–1.7 times first dorsal fin base; first dorsal fin height 0.6–1.4 times its base. Second dorsal fin somewhat similar in size to the first, slightly smaller in some specimens. Second dorsal fin origin opposite to the half-length of anal inner margin and insertion opposite to the anterior fourth of analcaudal distance. Anterior margin 1.2–1.4 times base of second dorsal fin; second dorsal base 1.2–1.5 times its height and 0.4–0.8 times the dorsal-caudal distance.

Anal fin subtriangular, apically narrow and not falcate; anal fin base 1.1–1.3 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 1.7–2.1 times the interdorsal distance and 1.1–2.0 times the dorsal-caudal distance. Anal anterior margin 0.8–1.3 times the posterior margin; anal fin height 0.3 times its base.

Caudal fin narrow-lobed and asymmetrical, lower caudal fin not produced as a lobe. Dorsal caudal lobe 2.2–2.9 times larger than preventral lobe; subterminal caudal margin 0.7–1.0 times the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Coloration. Dorsolateral surfaces tan to light-brown covered by white or cream-colored spots similar in size or larger than spiracle, randomly distributed throughout the body. Fins with no spots and slightly darker in their proximal region. Nine to eleven darker brown primary saddles without definite edging; 3–4 saddles anterior to the first dorsal fin and 6–7 posterior to it. Secondary saddles situated anteriorly to the first dorsal fin more conspicuous than in more posterior regions. Light spots less numerous or absent within saddles. Saddles and spots surpassing the lateral line ventrally only anteriorly to the first dorsal fin. Belly and ventral surface cream and uniform, with no spots.

Teeth. Monognathic heterodonty gradual and dignathic heterodonty weak ( Fig. 3 ); teeth row and series distributed in an alternated pattern and adjacent teeth along series independently arranged. Sexual heterondonty not observed, only adult male examined. Tooth counts 48–53/ 36-42. Parasymphyseal teeth smaller than anteriors, with one or two cusplets; cusplets one-third to half the height of the principal cusp ( Table 4 ). Crown base varying from straight to slightly concave ( Table 5 ). Undefined protuberances on the crown base; striae extending through the entire crown and more prominent in upper teeth. Ectodermal pits restricted to the crown base.

Anterior teeth with a principal cusp flanked by one cusplet on each side; cusplets one-third to half the height of the principal cusp. Crown base varying from slightly concave to concave. Protuberances well defined on the crown base in upper teeth; striae extending through almost the entire crown in upper teeth but absent in lower ones.

Antero-lateral teeth observed only in the upper jaw, shorter than anteriors. Principal cusp flanked by one cusplet on each side; cusplets one-third to half the height of the principal cusp. Principal cusp slightly oblique toward the commissure. Crown base slightly concave or concave. Protuberances on the crown base; striae extending through almost the entire crown.

Lateral teeth observed only in the upper jaw, larger than anterolaterals. Two to four cusplets, varying from one-third to half the height of the principal cusp. Principal cusp oblique toward the commissure. Protuberances on the crown base; striae extending through almost the entire crown. Ectodermal pits restricted to the crown base.

Posterior teeth smaller than anterior and lateral teeth, with one to three cusplets; proximal cusplets one-third to half the height of the principal cusp; marginal cusplet, when developed, half the height of the adjacent cusplet. 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 and more prominent in upper teeth. Ectodermal pits restricted to the crown base.

Commissural teeth smaller than posteriors, with none to four cusplets; proximal cusplets, when developed, half the height of the principal cusp; marginal cusplet, when developed, two-thirds the height of the adjacent cusplet. Principal cusp erect or slightly oblique toward the commissure. Crown base varying from straight to slightly concave. Protuberances on the crown base; striae can extend through almost the entire crown in upper teeth, and half the height of the principal cusp in lower teeth. Ectodermal pits restricted to the crown base.

Figures

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. 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. 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. 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.