Pycnocraspedum fulvum Machida, 1984

Schwarzhans, Werner W., Psomadakis, Peter N. & Nielsen, Jørgen G., 2025, Revision of the bathydemersal fish genus Pycnocraspedum (Ophidiidae; Teleostei), with description of two new species, Zootaxa 5636 (3), pp. 443-472 : 459-461

Pycnocraspedum fulvum Machida, 1984

Figures 1 , 3 , 5 , 8 , 12 ; Tables 1 , 2

Pycnocraspedum fulvum Machida, 1984: 246–249 , table 20, pl. 173, 28°06'N 126°23'E, Okinawa Trough .

Pycnocraspedum fulvum Machida, 1984 : Nielsen et al. (1999), Nakabo (2000), Nakabo (2002), Shinohara et al. (2005), Prokofiev (2005), Evseenko & Okiyama (2006), Prokofiev (2022).

Material examined: Holotype (unique specimen): BSKU 27497 , 336 mm SL, 28°06'N 126°23'E, Okinawa Trough , 143 m, 9 March 1978.

Diagnosis (updated from Machida, 1984). Precaudal vertebrae 13, total vertebrae 55; dorsal-fin rays 78; anal-fin rays 63; pectoral-fin rays 26; long gill rakers on first gill arch 4; pseudobranchial filaments 4; first dorsal-fin ray above first vertebra (D/V = 1); HL 26.4% of SL; body depth at vent 20.8% of SL; predorsal length 24.5% of SL; rear margin of preopercle with 3 spines, 2 lower and 1 upper, with spine number 2 being exceptionally strong; concave section without fleshy flap between spines 2 and 3; transversal scale rows above origin of anal fin 60, and above lateral line 19 (17 according to Machida, 1984); pyloric coeca 13; otolith: OL:OH = 2.4.

Description (updated, only additions to diagnosis). Relatively robust fish with moderately long tapering tail and rounded snout. Size of unique holotype 336 mm SL.

Meristics: caudal-fin rays 10; D/A = 22; V/A = 17.

Morphometrics in % of SL: diameter of orbit 4.4; upper jaw length 14.8; interorbital width 7.3; pelvic-fin base to anal-fin base 29.2; preanal length 44.2; prepelvic length 21.8; pectoral-fin length 15.9; pelvic-fin length not measurable (damaged).

Dentition. Basibranchial tooth patches 2 long median and 2 small lateral patches.

Otolith morphology (holotype). Size 25 mm in length; OL:OH = 2.4; OH:OT = 2.8. Thin, oval, elongated, anteriorly moderately projecting, posteriorly distinctly pointed, anterior and posterior tips slightly inferior. Dorsal rim broad, rounded, somewhat expanded and broadly crenulated. Ventral rim smooth, shallower than dorsal rim. Inner face moderately bent in horizontal and vertical directions, with very long, narrow, undivided sulcus reaching close to anterior and posterior rims of otolith. Sulcus with shallow, undivided, uniform colliculum with slightly concave dorsal rim and slightly convex ventral rim and rounded anterior and posterior tips. OL:CL = 1.3. Dorsal field with indistinct depression positioned high above sulcus; ventral field smooth, locally with faint radial furrows. Outer face with few radial furrows, slightly concave but with weak central bulge.

Coloration. Live coloration unknown. Color of preserved specimen light brown.

Discussion. Pyconocraspedum fulvum is readily recognized by the unusual low number of dorsal-fin rays (78) and the insertion of the first dorsal-fin ray above the first vertebra (D/V = 1). The number of anal-fin rays is also low at 63 and shared only with P. squamipinne (57–65). The number of transversal scale rows is low and shared only with P. squamipinne (60) and P. armatum (60) The otolith is relatively slender and large for the size of the head.

Distribution. Pycnocraspedum fulvum is only known from the unique holotype collected off Okinawa.

Figures

FIGURE 1. Radiograph figures of selected specimens of the genus Pycnocraspedum to visualize position of dorsal-fin rays in relation to first vertebra; “1” denotes the first dorsal-fin ray above the first vertebra; numbers with negative denotation represent dorsal-fin rays in front of the first vertebra. 1A) Pycnocraspedum armatum, USNM 227390; 1B) Pycnocraspedum phyllosoma USNM 227413; 1C) Pycnocraspedum squamipinne, ZMUC P771871; 1D) Pycnocraspedum fulvum (holotype), BSKU 27497.

FIGURE 3. Detail figures and drawings of preopercular spines and lower preopercular pores in Pycnocraspedum; preopercular spines are numbered from 1 through 4 from the lower angle of the preoperculum upwards; abbreviation lpp = lower preopercular pore. 3A–3B) Pycnocraspedum armatum, USNM 227412, 3A1-3A2 specimen 1 left side, 3A3 specimen 1 right side (mirror imaged), 3B specimen 2; 3C–3D) Pycnocraspedum phyllosoma, 3C USNM 421587, 3D USNM 421586; 3E) Pycnocraspedum fulvum (holotype), BSKU 27497; 3F–3G) Pycnocraspedum africanum sp. nov., 3F holotype, MNHN 2000-5691, 3G paratype, MNHN 2000-5692; 3H) Pycnocraspedum rowleyensis sp. nov., holotype, WAM I.28059.021; 3I–3K) Pycnocraspedum squamipinne, 3I lectotype, BMNH 1890.7.31.1, 3J ZMUC P771871, 3K ZMUC P771737.

FIGURE 5. Otoliths, inner faces (if not noted otherwise) shown from right side. 5A–5C) Pycnocraspedum africanum sp. nov., 5A holotype, MNHN 2000-5691 (5A2 dorsal view), 5B paratype MNHN 2000-5692, 5C tentatively assigned specimen, IRSNB (5C2 dorsal view, 5C3 anterior view); 5D–5E) Pycnocraspedum armatum, 5D USNM 227412 (5D2 ventral view), 5E USNM 227390 (5E2 ventral view); 5F) Pycnocraspedum fulvum (holotype), BSKU 27497 (5F2 ventral view, 5F3 anterior view); 5G) Pycnocraspedum rowleyensis sp. nov., holotype, WAM I.28059.021 (5G2 ventral view); 5H) Pycnocraspedum phyllosoma, USNM 421587 (5H2 ventral view, 5H3 anterior view); 5I–5K) Pycnocraspedum squamipinne, 5I lectotype, BMNH 1890.7.31.1 (5I2 ventral view), 5J ZMUC P771871, 5L ZMUC P771739 (5L2 ventral view), 5K ZMUC P771738 (5K2 ventral view); 5M) †Pycnocraspedum cetonaense (holotype) SMF P.5694 (5M2 dorsal view, 5M3 anterior view).

FIGURE 8. Pycnocraspedum fulvum Machida, 1984, radiograph of holotype, BSKU 27497, 336 mm SL, 28°06'N 126°23'E, 143 m.

FIGURE 12. Geographic distribution of the species of Pycnocraspedum. One symbol can represent more than one location.