taxonID	type	description	language	source
03A087E4AD71FFCEFF278D0717B3FF0C.taxon	type_taxon	Type species: Diplacanthopoma brachysoma Günther, 1887, by monotypy.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD71FFCEFF278D0717B3FF0C.taxon	diagnosis	Diagnosis: Scales absent from head, dorsal, and anal fins; prominent skin flap ending in a large pore above upper angle of opercle, near posttemporal; posterior infraorbital pores 2; large sensory pore on cheek (i. e., “ Diplacanthopoma ” pore); developed rakers on first gill arch 3 – 6; precaudal vertebrae 18 – 30; pectoral-fin rays 23 – 31.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD71FFCEFF278D0717B3FF0C.taxon	distribution	Distribution and habitat: Distributed in all tropical and subtropical seas, bathydemersal at depths of about 200 – 1,700 m on upper continental slopes. Species: 8 nominal species, many in need of revision, and several undescribed species.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD70FFC6FF278B471075F842.taxon	description	Figures 1 – 7	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD70FFC6FF278B471075F842.taxon	materials_examined	Holotype: ZMH-ICH- 0107333 (formerly ISH 1920 - 1968), adult (male), 259 mm SL, 24 ° 21 ’ S, 43 ° 54 ’ W, 2 March 1968, 487 to 500 m, RV Walter Herwig 1, cruise 23, station 90 / 68, collected by G. Krefft. Paratypes: USNM 485829, adult (female), 259 mm SL, 18 ° 56 ’ N, 94 ° 26 ’ W, 5 June 1970, 722 m, RV Oregon II, cruise 18, station 10962; USNM 485842, adult (female), 207 mm SL, 19 ° 28 ’ N, 92 ° 55 ’ W, 9 June 1970, 613 m, RV Oregon II, cruise 18, station 10984. Larva: USNM 465331, sex undetermined, 37.4 mm SL, ~ 5 miles east of Lake Worth Inlet, Florida, 2 March 2021 (night), collected by S. Kovacs.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD70FFC6FF278B471075F842.taxon	diagnosis	Diagnosis. Values and characters listed in brackets represent states for the only other Atlantic species, D. brachysoma. Precaudal vertebrae 20 – 23 [vs. 18 – 22]; total vertebrae 90 – 96 [vs. 75 – 94]; dorsal-fin rays 173 – 185 [vs. 125 – 164]; anal-fin rays 134 – 140 [vs. 88 – 127]; pectoral-fin rays 26 – 27 [vs. 22 – 26]; D / V = 7 – 8 [vs. 8 – 10]; D / A = 39 – 48 [vs. 34 – 44]; V / A = 26 – 29 [vs. 23 – 28]; HL: HD = 1.4 – 1.6 [vs. 1.7 – 2.0]; gill rakers on first arch 3 developed, 6 – 9 flattened platelets on lower arch, 2 – 3 platelets on upper arch [vs. 3 – 6 developed, 8 – 12 rudiments on lower arch, 3 – 4 rudiments on upper arch]; papillae on occiput, snout, below eye, and lower jaw [vs. absent]; ethmoid spine moderately elongate, dull tip [vs. short, sharp, often recurved tip]; frontal expanded laterally, interorbital broad [vs. not expanded, interorbital narrow]; frontal with lamellar bone extending above orbit [vs. reduced to absent], dermal integuments along central portion of lower lip [vs. absent]; OL: OH = 2.1 [vs. 1.8 – 2.1]; OL: TCL = 1.85 [vs. 1.85 – 2.15]; TCL: TCH = 1.45 [vs. 2.9 – 3.5]. Adult description. Compact species with large head, short, robust snout, and tapering tail (Figs. 1 – 2). Head naked, broad, high and relatively short, with distinctly concave dorsal profile. Many 1 – 2 mm long papillae (Fig. 2) on occiput, snout, below eye, and few on mandible; dermal integuments along central portion of lower lip. Opercle with 2 sharp, strong, extruding spines, upper one horizontal, lower one nearly vertical ventrally (Fig. 4). Eye and orbit relatively small, orbit diameter subequal to snout length. Maxilla extending posterior to vertical at posterior margin of eye, strongly widened posteriorly, rear part partly covered by thick skin. Anterior nostril small, positioned in short, fleshy tube low on snout; posterior nostril wide, anterior to lower margin of orbit. Body scaled, including regions immediately behind head and surrounding pelvic fins; scales cycloid. Sensory pores (Fig. 3): Supraorbital-canal pores 4, 1 st on tip of snout, 2 nd above and behind eye, 3 rd above commencement of opercle, 4 th (large) in broad skin flap above opercular spine. Infraorbital-canal pores 5, anterior pores 3, 2 in skin flap of upper lip, with small pore above, and posterior pores 2, positioned on upper lip distantly spaced from anterior infraorbital pores. Large “ Diplacanthopoma ” pore on rear central position on cheek. Mandibularcanal pores 6, anterior pores 3, 1 st at tip of lower jaw, 2 nd (large) inside tip of lower jaw, 3 rd (slit-like) in skinfold below lower lip, and posterior pores 3, set at subequal distances curving around lower mandible. Preopercular pores 2 (large) along rear skinfold over preopercle. A comparative drawing of the sensory head pores of D. brachysoma is also shown on Figure 3. Lateral-line origin immediately posterior to upper edge of opercle, running parallel to dorsal-fin base, becoming inconspicuous slightly before vertical through origin of anal fin. Lateral line noticeably darker on flank. Individual pores unable to be reliably counted. Dentition. All teeth small, uniform (Fig. 4). Vomer broad, triangular; palatine long, with 3 – 4 rows of small teeth; premaxilla tooth patch not fused to adjacent premaxilla anteriorly, with 4 – 5 rows of small teeth; dentary tooth patch not fused to adjacent dentary anteriorly, with 4 – 5 rows of small teeth. Basihyal and basibranchial tooth plates absent (Fig. 4). Hypobranchial 3 tooth plate present. Otolith morphology (Fig. 5; based on holotype). Size 10.1 mm in length; OL: OH = 2.1; OH: OT = 1.6. Thick, elongate, droplet-shaped otolith, anteriorly broadly rounded, posteriorly tapering. Dorsal rim highest anteriorly, overall shallow with long, straight central portion and weak, rounded post-dorsal angle near posterior tip of otolith. Ventral rim shallow, regularly curved. All rims smooth. Inner face completely flat with large, centrally positioned sulcus. Sulcus margins indistinct but single, large colliculum somewhat elevated and clearly discernable (used for measurements as total colliculum = TC), OL: TCL = 1.85. Colliculum wide, TCL: TCH = 1.45. Ventral margin of colliculum more strongly curved than dorsal margin. Dorsal and ventral fields smooth, narrow, without dorsal depression or ventral furrow. Outer face convex, smooth. Illustration of the otoliths from the Atlantic congener, D. brachysoma, shown in Figure 5 for comparison. For further information about extant ophidiiform otoliths see Nolf (1980) and Schwarzhans (1981). Coloration. Fresh-specimen coloration unknown. Color of preserved specimens light to medium brown; head slightly darker than body. Larval description. USNM 465331 (Fig. 6), postflexion. Counts: dorsal-fin rays 184; anal-fin rays 140; pectoral-fin rays undifferentiated; precaudal vertebrae 23, total vertebrae 90. Following description based on in-situ images as well as on observations of an ethanol-preserved, cleared-and-stained specimen. Head large, nearly as deep as long. Body elongate. Maxilla and premaxilla short, at oblique upturned angle. Premaxilla and dentary with small, distantly spaced teeth. Distal end of maxilla dorsoventrally expanded, posterior margin convex. Supramaxilla indistinguishable. Large rostral cartilage attached to ascending process of premaxilla. Short spine associated with symphysis of dentary. Eight branchiostegals (full complement). Three elongate gill rakers present on first arch. Other tooth plates of branchial arches not developed. Body and head scaleless. Pectoral fin small, radials and fin rays undifferentiated. Coracoid with elongate cartilaginous ventral process, extending to level of anterior gut. Gut large, lacking exterilium morphology of some other larval ophidiids (Fraser & Smith 1974; Fahay & Nielsen 2003; Okiyama 2014; Girard et al. 2023 b). Gut with single, broad intestinal loop in posterior half of tract, near the 14 th – 15 th vertebra. Anus slightly anterior to anal fin. Pelvic fin indistinguishable. Caudal fin small, with ~ 10 rays; without procurrent rays, medial rays longest. Hypurals undifferentiated. Melanophores absent from oral jaws. Melanophores present above frontal, along dorsal and ventral edges of body, minute. Body almost completely transparent. Fine, dense areas of reflectance or iridescence covering dorsal part of head, dorsal, anal, and caudal fins. These areas not discernible in preserved specimen. Melanophores dorsal to gut more pronounced than body melanophores.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD70FFC6FF278B471075F842.taxon	etymology	Etymology. Named for blackwater SCUBA diver and photographer Steven Kovacs for his dedication to the discovery, photography, collection, and identification of larval fishes.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
03A087E4AD70FFC6FF278B471075F842.taxon	distribution	Distribution. The holotype was collected off the continental margin on the slope off southern Brazil, whereas the paratypes were collected off Tabasco and Veracruz, Mexico, in the Bay of Campeche (Fig. 7). Although the larva was collected off the eastern coast of Florida, we have not identified an adult specimen of this species from north of the Bay of Campeche. Diplacanthopoma kovacsi is sympatric with D. brachysoma for at least the southern part of the range of D. brachysoma. Genotypic data. The barcode sequence from the larva (USNM 465331: GenBank Nucleotide PZ 298824) was compared to sequences from adult and larval specimens of Diplacanthopoma brachysoma (USNM 407635: GenBank Nucleotide PZ 298825; USNM 465413: GenBank Nucleotide PZ 298823) and was found to be ≥ 9 % divergent. Larval description of D. brachysoma. USNM 465413 (Fig. 8), postflexion. Counts: dorsal-fin rays 146; anal-fin rays 106; pectoral-fin rays undifferentiated; precaudal vertebrae 21, total vertebrae 83. Following description based on in-situ images as well as ethanol and cleared-and-stained specimen. Head large, nearly as deep as long. Body elongate. Maxilla and premaxilla short, at oblique upturned angle. Premaxilla and dentary with small, distantly spaced teeth. Distal end of maxilla dorsoventrally expanded, posterior margin convex. Supramaxilla indistinguishable. Large rostral cartilage attached to ascending process of premaxilla. Eight branchiostegals (full complement). Gill rakers and other tooth plates of branchial arches not developed. Body and head scaleless. Pectoral fin small, radials and fin rays undifferentiated. Coracoid with elongate cartilaginous ventral process, extending to level of anterior gut. Gut large, lacking exterilium morphology of some other larval ophidiids (Fraser & Smith 1974; Fahay & Nielsen 2003; Okiyama 2014; Girard et al. 2023 b). Gut with single, broad intestinal loop in posterior half of tract, near the 13 th-to- 14 th vertebra. Anus slightly anterior to anal fin. Pelvic fin indistinguishable. Caudal fin small, rays undifferentiated. Hypurals undifferentiated. Melanophores absent from oral jaws, frontal, and along dorsal of body until ~ 18 th vertebra. Melanophores present in dense band dorsally from 18 th vertebra to caudal fin and ventrally from anal-fin origin to caudal fin. Body almost completely transparent. Band of yellow reflectance or iridescence below vertebrae from head to caudal fin. Blotches of yellow reflectance or iridescence along anal fin. It is unclear if this area is yellow in life or the result of strobes used in photography. Minute areas of white reflectance or iridescence along dorsal fin and dorsal part of head. These areas not discernible in preserved specimen. Melanophores dorsal to gut present in dense band, with greatest density above gut loop. Genotypic data. The barcode sequence from the larva (USNM 465413: GenBank Nucleotide PZ 298823) was compared to a sequence from an adult specimen of D. brachysoma (USNM 407635: GenBank Nucleotide PZ 298825) and was 99.7 % identical, differing by 2 base pairs.	en	Girard, Matthew G., Moritz, Timo, Schwarzhans, Werner (2026): A new species of Diplacanthopoma (Teleostei: Bythitidae) from the western Atlantic, with comments on the discovery and description of larval forms of two western Atlantic species. Zootaxa 5831 (1): 19-34, DOI: 10.11646/zootaxa.5831.1.2, URL: https://doi.org/10.11646/zootaxa.5831.1.2
