Etmopterus lucifer Jordan & Snyder 1902

Etmopterus lucifer Jordan & Snyder, 1902 (Figs 3 B, 4 B, 5 B, 6 B, D, 7 B, D, 9, 10, 11; File S 2: Table S 2) Etmopterus lucifer Jordan & Snyder, 1902: 79, fig. 1 [original description; lectotype: CAS - SU 6863 (designated herein), off Misaki, Japan, 35°14'N, 139°37'E; paralectotypes in CAS, USNM; see Comments on type specimens]; Jordan and Fowler (1903): 634, fig. 5 (brief description); Böhlke (1953): 10; Nakaya in Okamura et al. (1982): 48, 49, 312, plate 12 (description in Japanese and English); Shirai in Amaoka et al. (1983): 46, 47, 164, plate 2 (description in Japanese and English); Compagno (1984): 70, 79, 80 (listed in key, description); Yamakawa et al. (1986): 197 –207, fig. 6 C (revision of the E. lucifer group in Japan; brief description; listed in key); Bass et al. (1986): 55, 56, fig. 5.13 (listed in key, brief description); Howe and Springer (1993): 9 (type catalogue with remarks); Compagno and Niem (1998): 1220, 1226 (listed in key, brief description); Compagno (1999): 473 (listed); Nakabo (2000): 146 (listed in key), Compagno in Randall and Lim (2000): 580 (listed in key); Nakabo (2002): 146 (listed in key); Last et al. (2002): 223 (listed in key); Dyldin (2015): 55 (listed); Weigmann (2016): 896 (listed, northwest Pacific); Ebert et al. (2017): 380 (listed in key, erroneously listed in central north Pacific); Ebert and van Hees (2018): 207 (listed in key); Ebert et al. (2021): 15 (listed in key); Ng et al. (2024 b): 181, fig. 5 F. Etmopterus burgessi Schaaf-Da Silva & Ebert, 2006: 55, figs 1, 2 [original description; holotype: CAS 223476, from Ta-Chi (= Daxi), northeastern Taiwan; 3 paratypes]; Ho and Shao (2011): 19 (listed); Ebert et al. (2013): 293 (listed), Weigmann (2016): 58 (listed); Ebert et al. (2017): 379 (listed in key); Ebert and van Hees 2018: 207 (listed in key); Ebert et al. 2021: 14 (listed in key). Materials examined. 51 specimens. Lectotype (designated herein): CAS - SU 6863, mature male 264 mm TL, off Misaki, Japan, 35°14'N, 139°37'E, depth and date unknown. Paralectotype: CAS - SU 7832 (1 of 4 specimens), mature male 284 mm TL, collected with the lectotype. Holotype of Etmopterus burgessi: CAS 223476, mature male 355 mm TL, Daxi, Taiwan, 24°53'N, 122°01'E, 300 m, 11 May 1988. Paratypes of Etmopterus burgessi: CAS 223477, female 405 mm TL, CAS 223478, female 241 mm TL, CAS 223479, female 235 mm TL, Daxi, Taiwan, 24°53'N, 122°01'E, 300 m, 21 May 2005. Non-types: ASIZP 0060498 (2 specimens), females 345–357 mm TL, 24°56'N, 121°54'E, off Daxi, northeastern Taiwan, 10 February 1997; CAS - SU 26782, female 305 mm TL, Japan, depth and date unknown; EBFS-NG 00020, juvenile female 150 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 15 April 2022; EBFS-NG 00047, mature male 317 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 19 November 2021; EBFS-NG 00048, mature male 342 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 25 November 2022; EBFS-NG 00049, female 298 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 1 March 2022; EBFS-NG 00074, mature male 313 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 9 July 2021; EBFS-NG 00105, mature male 371 mm TL, off Donggang, southwestern Taiwan, ca. 22°N, 120°E, ca. 400 m, 25 March 2022; EBFS-NG 00124, mature male 324 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 18 May 2022; EBFS-NG 00142, mature male 328 mm TL, EBFS-NG 00143, juvenile female 204 mm TL, EBFS-NG 00144, female 314 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 8 July 2022; EBFS-NG 00145, juvenile female 189 mm TL; EBFS-NG 00146, juvenile female 247 mm TL, EBFS-NG 00147, juvenile female 284 mm TL, EBFS-NG 00148, juvenile female 274 mm TL, EBFS-NG 00149, juvenile male 287 mm TL, EBFS-NG 00150, juvenile male 296 mm TL, EBFS-NG 00151, juvenile male 261 mm TL, EBFS-NG 00152, juvenile male 284 mm TL, EBFS-NG 00153, juvenile male 315 mm TL, EBFS-NG 00154, juvenile male 300 mm TL, EBFS-NG 00155, mature male 333 mm TL, EBFS-NG 00156, mature male 334 mm TL, EBFS-NG 00157, mature male 365 mm TL, off Daxi, northeastern Taiwan, ca. 24°53'N, 122°00'E, ca. 400 m, 30 May 2022; EBFS-NG 00267, off Donggang, southwestern Taiwan, ca. 22°N, 120°E, ca. 400 m, 24 August 2022; EBFS-NG 00270, female 259 mm TL, EBFS-NG 00271, mature male 313 mm TL, EBFS-NG 00272, female 213 mm TL, EBFS-NG 00273, EBFS-NG 00274, EBFS-NG 00275, off Donggang, southwestern Taiwan, ca. 22°N, 120°E, ca. 400 m, 7 October 2022; EBFS-NG 00286, juvenile female 165 mm TL, EBFS-NG 00287, juvenile male 173 mm TL, EBFS-NG 00288, juvenile male 175 mm TL, EBFS-NG 00289, juvenile male 161 mm TL, off Donggang, southwestern Taiwan, ca. 22°N, 120°E, ca. 400 m, 9 November 2022; EBFS-NG 00323, juvenile male 290 mm TL, EBFS-NG 00324, juvenile male 321 mm TL, off Donggang, southwestern Taiwan, ca. 22°N, 120°E, ca. 400 m, 10 January 2023; EBFS-NG 00354, juvenile male 287 mm TL, South China Sea, ca. 19°N, 114°E, ca. 500 m, 12 March 2023; HUMZ 214505, off Tohoku, Japan, 40°17'N, 142°16'E, 441–459 m, 10 October 2011; HUMZ 232154, neonate female 131 mm TL; HUMZ 232155, mature male 268 mm TL, off Miyagi, Japan, 38°36'N, 142°02'E, 378 m, 22 October 2021; HUMZ 232462, female 358 mm TL, off Tomakomai, Japan, 42°13'N, 141°41'E, 656–684 m, 24 November 2021; NTUM 16305, mature male 283 mm TL, CP 4175, northeastern Taiwan, ca. 25°25'N, 122°08'E, ca. 434–535 m, 28 June 2018; USNM 51282, mature male 285 mm TL, off Sagami Bay, Japan, depth unknown, 1900. Diagnosis. A moderately small Etmopterus of the E. lucifer group by showing elongated anterior and posterior branches of lateral flank marking, and differing from other members of the E. lucifer group by the following combination of characters: hook-like dermal denticles not overlapping each other, in well-defined rows; origin of second dorsal fin anterior to flank-marking base origin; infracaudal marking not connected with caudal-fin base marking through luminous lines; posterior caudal-fin marking long, its length 23.1–39.8 % caudal-fin length; and ventral pectoral marking knife-shaped, straight. Redescription. Morphometric information is provided in File S 2 (Table S 2). Proportional measurements and tooth counts are provided as ranges for the paralectotype and the non-types, followed by the lectotype (designated herein) in parentheses (if available). A precise tooth count of the lower jaw teeth is not possible in the lectotype as several teeth are missing. Trunk sub-cylindrical, body width narrower than to slightly wider than height; abdomen longer than lower caudal peduncle; head subconical, slightly depressed. Snout moderately short (Fig. 10), snout narrowly rounded in lateral and dorsal view. Eye oval. Spiracle bean-shaped. Gill openings moderate, slightly curved. Mouth broad, nearly straight. Teeth dissimilar in upper and lower jaw, exhibiting ontogenetic change and sexual dimorphism; upper teeth multicuspid in three functional series; lower teeth unicuspid, in three series, one functional; lower teeth blade-like, with strongly oblique cusp. No distinctive symphyseal and intermediate teeth. Upper teeth cusp thick; immature males and females with 1–2, rarely 3 cusplets on each side of the upper teeth, while mature males having 3, rarely 2 or 4 cusplets (Fig. 3 B); longest cusplet length about two-third of the cusp in mature individuals; cusp and cusplets of upper teeth narrowly triangular, lower teeth of mature individuals not erected. Tooth count of upper jaw 22–28 (25), lower jaw 25–35, total count 47–62. D 1 rather small, with a round apex, origin usually posterior to a vertical line through P 1 free rear tip. D 2 larger than D 1, apex angular, posterior margin remarkably concave, free rear tip moderately elongated; D 2 spine long and curved. P 1 with moderate size, and angular free rear tips, base narrow, posterior margin slightly concave. P 2 narrowly triangular. Clasper of mature males moderately long. Caudal fin elongate, caudal folk not especially developed; terminal lobe broad. Dermal denticles hook-like, rather high, reclined backwards, widely-spaced, not overlapping, giving a rough texture of the skin, in defined rows (Fig. 4 B); denticles present on underside of snout, except for a broad area around mouth; underside of gill slits fully covered with denticles (small bare patch maybe present between underside of gill slits in juveniles); P 1 inner margin with a broad naked area, D 1, D 2 and P 2 inner margins with narrow naked areas; denticles present on fin bases; denticles scarcely present on fins in neonates, increasing the coverage to most of the areas of ceratotrichia, particularly on D 2 (Fig. 5 B). Body lateral side with very short, dash-like markings which are usually difficult to observe after preservation; head dorsal surface scattered dot-like markings; dorsal contour of the body with a single line of dot-like markings, extending mid-dorsally from about the level of anterior fontanelle to the D 2 origin; ventral pectoral marking knife-like, straight, the tip not reaching P 1 insertion (Fig. 6 B, D). Flank markings well defined, with elongated anterior and posterior branch; anterior flank marking slender, very slightly curved, extending above P 2 origin; posterior flank marking straight, usually thicker, shorter than anterior flank marking; anterior flank marking length 101.7–180.4 (167.4) % posterior flank marking; posterior flank marking not extending beyond D 2 free rear tip; flank marking base rather narrow, origin well posterior to D 2 origin. Infracaudal marking prominent, extending from flank marking base to about the same level of posterior flank marking tip, not connecting to the caudal-base marking by a pair of lines (Fig. 7 B, D); caudal-base marking broad, with a moderately thick, slender extension, bifurcate before the lower caudal-fin origin, 15.7–38.5 (29.6) % caudal-fin length. Posterior caudal-fin