Barathronus algrahami, Nielsen & Pogonoski & Appleyard, 2019

Nielsen, Jørgen G., Pogonoski, John J. & Appleyard, Sharon A., 2019, Aphyonid-clade species of Australia (Teleostei, Bythitidae) with four species new to Australian waters and a new species of Barathronus, Zootaxa 4564 (2), pp. 554-572 : 560-562

Barathronus algrahami n. sp.

Table 2, Figs. 1 , 3–5

urn:lsid:zoobank.org:act:73E5BBC3-AB37-4B2E-BB4C-983C9A5C0E2A

Barathronus maculatus: Yeh et al. 2009: 228 .

Holotype. CSIRO H 1932-01 , female, 200 mm SL, west of Cape Martin, SA, 37°27.30’S, 138°38.28’E, FRV Soela , field no. SO 01/89/41, demersal trawl, 1300– 1230 m, 30 Jan. 1989.

Paratypes. (4 specimens, 85–195 mm SL). ASIZ P0064071 , female, 170 mm SL, off Su-ao , eastern Taiwan, 24°25.43’N, 122°21.40’E , RV Ocean Researcher I, cruise 657, st. CD199, otter trawl, 1134–1188 m, 12 Sep. 2002 . ASIZ P0066252 (GenBank Accession KU 943179 ), female, 195 mm SL, off Su-ao , eastern Taiwan, 24°23.4’N, 122°14.4’E , RV Ocean Researcher I, st. OCP279, ORE beam trawl, 1224–1270 m, 14 Jun. 2005 . ASIZ P0066254 (GenBank Accession KU 943180 ), female, 195 mm SL, off Su-ao , eastern Taiwan, 24°24.15’N, 122°14.06’E , RV Ocean Researcher I, st. CP281, beam trawl, 1162–1240 m, 15 June 2005 . ASIZ P0068057 , unripe male, 85 mm SL, Aurora, Philippines, 15°00.47’N, 123°12.60’E, st . CC2703 , otter trawl, 1191–1262 m, 27 May 2007 .

Size. Largest known specimen (200 mm SL) is a ripe female.

Diagnosis. Barathronus algrahami is long, robust and slightly compressed. Dorsal fin with 69–78 rays, caudal fin with 8-10 rays, anal fin with 60–67 rays and pectoral fin with 21–25 rays, precaudal vertebrae 34–37, total vertebrae 74–81, origin of dorsal fin above vertebra 27–30, anterior gill arch with 27–32 long rakers, 3–5 fangs on vomer and 3–5 on each dentary, predorsal length 47.0–52 % SL, otolith small (3 mm long in 200 mm holotype), no pigment laterally on body, dark blue peritoneum and newly caught specimen reddish all over. It reaches a SL of 200 mm, only surpassed in the genus by B. maculatus that reaches 225 mm SL.

Description. The principal meristic and morphometric characters are shown in Table 2. The description is based on the holotype; characters in which the paratypes differ from the holotype are given in brackets. Head short. Body compressed. Skin loose, transparent and scaleless. Origin of dorsal and anal fins behind midpoint of fish. Tip of pectoral fins end well in front of dorsal fin. Eyes not externally visible. Mouth cleft oblique. Pelvic fin length about two third of pectoral fin. Anterior nostril placed close to upper lip. Anterior gill arch with one short and four (five) long rakers on upper branch, one long raker in the angle and lower branch with 22 (25) long and one short raker. Pseudobranchial filaments two.

Axial skeleton (from radiographs). Precaudal vertebrae 35 (34–37) all with pointed tip. Anterior neural spine equal in length to second spine. The spines then decrease in length until the posteriormost ten precaudal spines which increase in length posteriorad. Parapophyses on precaudal vertebrae 8–35. Pleural ribs on vertebrae 3–8. Epipleural ribs not observed. Vertebral centra hour-glass shaped.

*broken in many specimens

# the number of specimens from which data could be collected for each character in B. maculatus

Dentition. Vomer with 3 (3–5) long, retrorse fangs. Each dentary with 4 (3–5) fangs like those on vomer placed posteriorly and on anterior half numerous, tiny, pointed and close-set teeth. Premaxillaries with small pointed teeth in irregular rows. Palatines edentate.

Otolith ( Fig. 4 ). Small, subcircular sagittal otolith twice as long as thick with a poorly developed centrally placed sulcus one fourth the length of the sagitta.

Coloration. Fig. 3A shows the holotype when freshly caught dominated by reddish colors and a very dark peritoneum. After 29 years of preservation ( Fig. 3B ) the reddish color is completely gone and the brownish musculature and dark peritoneum is seen through the transparent skin.

Biology. The four adult specimens are all females and the 85 mm SL specimen is an unripe male. The holotype has very distended ovaries holding 100+ embryos 9–10 mm long with brown eyes and a brown line dorsally and ventrally from head to caudal tip ( Fig. 5 ).

Distribution ( Fig. 1 ). Barathronus algrahami occurs off SA, off eastern Taiwan and off Aurora, Philippines, at bathyal depth (1134–1300 m).

Etymology. The new species is named after Alastair Graham (CSIRO, Hobart), acknowledging his assistance with loans of specimens and data.

Remarks. Of the ten valid Barathronus species B. algrahami seems most close to B. maculatus , but differs among other characters by not having distinct brown pigment laterally, predorsal length 47.0–52 % SL vs 37.0– 48.0 and length of otolith half the size of the otolith from a specimen of same standard length; B. algrahami has a dark blue peritoneum vs transparent peritoneum in B. affinis , B. linsi , B. multidens , B. pacificus , B. parfaiti and B. unicolor ; it differs from B. bicolor and B. diaphanus by having more anal fin rays 60–67 vs 46–59. The remaining Barathronus species, B. bruuni , is known from a juvenile holotype (39 mm SL) from which B. algrahami differs by having fewer anal fin rays (60–67 vs 73).

Figures

FIGURE 1. Records of aphyonid-clade species in Australian waters including the non-Australian paratypes of Barathronus algrahami n. sp. Some symbols represent more than one specimen (Image © NASA, TerraMetrics, Google Earth).

FIGURE 3. Barathronus algrahami, CSIRO H 1932-01, holotype, female, 200 mm SL: A—photo when newly caught (Image: CSIRO Australian National Fish Collection), B—photo after 29 years of preservation (Image: Marcus Krag).

FIGURE 4. Right otolith from Barathronus algrahami, CSIRO H 1932-01, holotype, female, 200 mm SL: A—inner face, Bventral view.

FIGURE 5. Embryo (10 mm) from Barathronus algrahami, CSIRO H 1932-01, holotype (Image: Anders Illum).