Chauanx africanus , Ho, Hsuan-Ching & Last, Peter R., 2013

Ho, Hsuan-Ching & Last, Peter R., 2013, Two new species of the coffinfish genus Chaunax (Lophiiformes: Chaunacidae) from the Indian Ocean, Zootaxa 3710 (5), pp. 436-448: 442-447

publication ID

http://dx.doi.org/10.11646/zootaxa.3710.5.3

publication LSID

lsid:zoobank.org:pub:C08B7E1F-E4DC-44FD-B040-5AB8FFA027CB

persistent identifier

http://treatment.plazi.org/id/03C787E7-FF9C-FFCE-5AB5-F9D2441F08AD

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scientific name

Chauanx africanus
status

n. sp.

Chauanx africanus  n. sp.

English name: African Coffinfish Figs. 4View FIGURE 4 A–C, 5 A–C; Table 1

Holotype. SAIAB 74595 (227 mm SL), 18 ° 2.1 ’S, 37 ° 37.2 ’ E, north of Beira, Mozambique, Africa, western Indian Ocean, 162–200 m, 12 Aug. 2002.

Paratype. SAIAB 18878 (142 mm SL), collected together with the holotype.

Diagnosis. A member of the C. fimbriatus  -species group distinguished from its congeners in having: body covered by variable-sized, irregular brownish patches and a complex white reticulate pattern; eye surrounded by prominent radiating brownish markings; 2–3 pairs of narrow brownish bars at dorsal-fin base; pale reticulate markings frequently double-lined; pattern extending forward to front of lower jaw, and over pectoral and caudal fins; 3–4 pairs of spinules bridging each neuromast; 8–9 rakers on second gill arch; illicium short and stout; illicial trough small, oval in shape; numerous thin pale cirri with brown tips on esca; gill chamber pale; peritoneal membrane black; and lateral-line neuromast distribution BD= 2, CD= 6–7, FG= 3, GH= 10–12, BI = 31–32.

Description. Morphometric and meristic details are given in Table 1; following data summary is provided for holotype, followed by those of paratype, if different, in parentheses.

Dorsal-fin rays III, 12; pectoral-fin rays 14 (13); anal-fin rays 7 (6); caudal-fin rays 9. Head length 2.3 in SL; head width 4.2 (4.1) in SL, 1.8 in HL; pre-dorsal length 2.0 (1.9) in SL; pre-gill opening length 1.5 (1.6) in SL; prepreopercular length 3.5 (3.4) in SL, 1.5 in HL; upper jaw 4.5 (4.6) in SL, 1.9 (2.0) in HL; illicial length 9.9 (15.5) in HL; eye diameter 6.7 (6.2) in HL; post-dorsal fin length 6.1 (5.7) in SL, 2.7 (2.5) in HL; post-anus length 2.8 (3.2) in SL, 1.2 (1.4) in HL; post-anal fin length 8.7 (7.3) in SL, 3.8 (3.2) in HL; caudal peduncle depth 4.5 (4.4) in HL; caudal-fin length 3.6 (3.5) in SL, 1.6 (1.5) in HL.

Head globular, skull elevated above rest of body posteriorly; trunk and tail robust, weakly compressed, tapering posteriorly to caudal-fin base; ventral surface of belly flattened; skin thick, loose and flaccid; interspace between eyes broad, convex; caudal peduncle short. Eyes rounded, directed laterally; covered by dermal membrane, broadly connected to adjoining skin, forming clear “window”.

Illicium stout and short, its length less than eye diameter; esca depressed, forming a large central plate bearing many thin cirri; second dorsal-fin spine close to illicium, embedded under skin and not detectable externally; third dorsal-fin spine situated at about midpoint of predorsal distance, embedded beneath skin. Illicial trough ovalshaped, concave, slightly narrow anteriorly and much broader posteriorly, its length slightly more than its width. Origin of soft dorsal fin slightly behind midpoint of body; pectoral fin emerging laterally near midpoint of body, slightly anterior to a vertical through gill opening; pelvic fin on breast, well anterior to pectoral fin; anus situated near posterior fourth of body; anal-fin origin near posterior fifth of body, its tip nearly reaching caudal-fin base when depressed.

Nostrils anterior to eye; anterior nostril surrounded by fleshy membrane, its posterior part taller than anterior part; posterior nostril a circular depression; mouth wide, superior, its opening nearly vertical; lower jaw robust, protruding slightly in front of upper jaw; maxilla tapering, narrow dorsally, broadly expanded ventrally; blunt symphysial spine on symphysis of lower jaw.

Broad transparent membrane on first gill arch; first ceratobranchial well connected to, and first epibranchial entirely free of opercular wall; gill filaments present on second to fourth gill arches, two rows of gill filaments in second and third gill arches, single row of gill filaments on fourth gill arch; filaments on inner rows of third and fourth gill arches about two-thirds length of filaments on other arches; inner surface of fourth gill arch completely connected to body. Single row of 12 (13) rakers on 1 st gill arch, 3 on upper limb and 9 (10) on lower limb, 8 (9) rakers on outer row of 2 nd arch, 9 rakers on outer row of 3 rd arch, and single row of 8 (7) rakers on 4 th arch.

Interspaces of lateral-line neuromast complex slightly longer than its width; 3–4 (mainly 3) pairs of short spines bridging each neuromast. Lateral-line neuromast counts: supraorbital (AB) 11; premaxillary (AC) 8; upper preopercular (BD) 2; infraorbital (CD) 6 (7); lower preopercular (DG) 3; mandibular (EF) 6; hyomandibular (FG) 3; pectoral (GH) 11 or 12 (10); anterior body proper (BB') 4; supratemporal (BB) 6; and body proper ( BI) 31 (32), including 2 or 3 on caudal fin.

Dorsal surface covered by simple, stout spinules, except for eye window, lips, distal fifth of dorsal surface, entire ventral surface of pectoral fin, distal half of dorsal surface, entire ventral surface of pelvic fin, entire anal fin and its base, membranes of dorsal fin, anus, and caudal-fin rays. Ventral surface covered by slightly shorter, firm spinules. Jaws and body margin along lateral line densely covered with simple, stout cirri; entire dorsal surface covered by scattered simple cirri, relatively dense on supraocular membrane and lower portion of maxilla; cirri on dorsal surface and supraocular membrane accompanied by a strong spinule, taller than those adjacent. Cirri absent from ventral surface.

Coloration. Fresh color unknown. When preserved: dorsal and lateral surfaces of body still covered by prominent, variable-sized, irregular brownish patches overlain by a complex pale reticulate pattern. Pattern extending to front of chin, covering dorsal and caudal fins, and over dorsal surface of pectoral fin. Elongate brownish bars on head, and bases of dorsal and caudal fin; those around eye forming distinctive radiate pattern; symmetric pair of dark-brown markings at sphenotic region, lower preopercular region, and anterior to gill opening; symmetric pairs of bars at origin and middle portion of dorsal-fin base; medium patch near third dorsalfin spine and at caudal fin base. Pale reticulate pattern complex; numerous small patches forming chain-like, double-lined pattern over dorsum and sides, and bordering large brownish patches; pale reticulate pattern sometimes coalesced to form pale spots; larger brownish patches with scattered pale reticulations at lower opercular region. Uppermost 6 rays of caudal fin covered by alternating broad brown and narrow pale bands, lowermost three rays pale. Pelvic fin pale; underside of pectoral fin pale. Gill chamber, gill arches and buccal cavity pale; peritoneum blackish dorsally with scattered blackish patches on pale background ventrally; external lining of stomach pale.

Size. At least 227 mm SL, based on the two known types.

Etymology. The specific name africanus  refers to the regional locality of the types, and its decorated color pattern is reminiscent of some strikingly coloured African animals, such as the giraffe.

Distribution. Known only from the two type specimens, collected from the outer continental shelf north of Beira, Mozambique, western Indian Ocean, at a depth of 162– 200 m. Probably endemic in the southwestern Indian Ocean.

Remarks. Chaunax africanus  n. sp. can be distinguished from other members of the C. fimbriatus  -species group by its unique dorsal coloration. It is morphologically most similar to C. nebulosus  and C. reticulatus  , but differs mainly in having long, deep-brown bars on its body surface (vs. dark bars absent). It also differs from C. fimbriatus  , as does C. nebulosus  , mainly in lacking two large white spots on the dorsal surface, and having 6 neuromasts in the infraorbital series (CD) and 3 in the lower preopercular series (DG) (vs. 7 and 4 respectively); and from C. umbrinus  in lacking a fine reticulate colour pattern and having 10–12 neuromasts in the pectoral series and 31–32 on the body proper (vs. 13 and 33–38, respectively).

Comments on members of the C. fimbriatus  -species group. There are presently six species recognized in the C. fimbriatus  -species group: C. fimbriatus  , C. umbrinus  , C. flammeus  , C. reticulatus  , C. nebulosus  n. sp. and C. africanus  n. sp. These species can be distinguished from all other members in the genus in having cirri present on the dorsal head (including a dense cluster above the eye), 3 or more (usually more) pairs of spines bridging the neuromasts, and, if present, a complex pattern of spots or reticulations on the dorsal surface.

Of the group, C. flammeus  probably is the most poorly known nominal species, represented conclusively only by the unique holotype collected off northern Madagascar in the western Indian Ocean. Le Danios (1979) mentioned that the holotype had yellowish spots when fresh, which faded totally after preservation. Other species in C. fimbriatus- group retain a grayish or brownish color pattern dorsally, even after long-term preservation. Chaunax flammeus  seems to be either plain reddish or with yellowish spots when fresh, distinguishing it from all other members of the fimbriatus  -group.

Chaunax umbrinus  is also poorly known, represented only by a few specimens collected from the Hawaiian Islands and the Emperor Seamount (based on specimens deposited in the National Science Museum, Tokyo). It can be distinguished mainly by its very fine reticulate pattern on the dorsal surface, even in large individuals. Other characters that might be used to distinguished it from its congeners in the C. fimbriatus  group are mainly 13 neuromasts in the pectoral series (vs. 12 or less in its congeners) and slightly more numerous neuromasts on the body proper (33–38, vs. 29–37 in its congeners).

Chaunax fimbriatus  is commonly collected from the seas around Japan and Taiwan, but has not been reliably reported from outside this part of the western North Pacific. The first author regularly collected this species from northern Taiwan, but only one specimen has been confirmed in the past 15 years from off southwestern Taiwan (off Tungkang). This species may inhabit the East China Sea and/or the Okinawa Trough, but rarely occurs in the South China Sea. Chaunax fimbriatus  can be distinguished from its congeners mainly by the two large pale patches on its dorsal surface, one associated with the embedded third dorsal spine and another before the origin of the soft dorsal fin, and mainly 4 neuromasts in the lower preopercular series (vs. mainly 3 in other congeners). Record of this species from Hawaii (Chave & Mundy 1994 is misidentification of Chaunacops cf. coloratus  and those of Mundy 2005), the western central Pacific (Caruso 1999), Australia (Paxton et al. 1989), and New Caledonia (Fricke et al. 2011), are most likely invalid and need to be checked.

Chaunax reticulatus  ( Fig. 3View FIGURE 3) was described from New Zealand, New Caledonia and eastern Australia. It differs from congeners mainly by the pale reticulate pattern on a grayish background in juveniles, and fine brownish spots on its dorsal surface in adults.

Comments on species occurring in the Indian Ocean. The following species have been described or recorded from the Indian Ocean: C. apus  , C. pictus  , C. cf. fimbriatus  (sensu Hutchins 2001), C. flammeus  , C. umbrinus  , and C. penicillatus  .

Chaunax apus  ( Fig. 6View FIGURE 6) was described based on a single specimen collected from the Bay of Bengal. Only a few species had been described before this species, C. pictus  , Chaunax nuttingi Garman 1896  (= C. pictus  ), C. fimbriatus  and C. umbrinus  . The first author examined the holotype of C. apus  and determinated that it belongs to the C. abei  -species group (sensu Ho & Shao 2010), which is characterized by its lack of filaments on the dorsal surface of the head and flap-like cirri laterally on the body associated with the lateral line. As C. pictus  is in the C. pictus  -species group (sensu Caruso, 1989) and both C. fimbriatus  and C. umbrinus  are in the C. fimbriatus  -species group (sensu Ho et al., 2013, not Caruso, 1989), none of the three is conspecific with C. apus  . Le Danios (1979) suggested that C. apus  was a junior synonym of C. endeavouri Whitley 1929  , an impossibility as C. apus  was described before C. endeavouri  . We provisionally recognize C. apus  as a valid species in the C. abei  -species group but caution that it needs further study.

Although C. pictus  has been recorded globally, confirmed identifications are only known from the Atlantic Ocean (Caruso, 1989) and Mediterranean Sea (Ragonese & Giusto, 2005); we have seen no specimens from outside the Atlantic Ocean among the substantial amount of material we examined. Based on our observations, records of C. pictus  from outside the Atlantic Ocean are likely to be misidentifications of various species, notably C. nudiventer  ( New Zealand; Ho et al. 2013), C. abei  ( Japan and Taiwan), and some unidentified/undescribed species in Australia and South Africa (Ho, pers. observ.).

Le Danios (1979) described C. umbrinus flammeus  based on a single specimen collected from northern Madagascar. Examination of the holotype and the original drawing show that it is clearly a member of C. fimbriatus  -species group (sensu Ho et al., 2013). Its unique coloration indicates that it should be treated as a valid species distinct from the three other nominal species of the complex (i.e. C. fimbriatus  , C. umbrinus  and C. reticulatus  ), and two new Indian Ocean species described herein.

Although Fricke (1999) recorded C. umbrinus  from Reunion Island, western Indian Ocean, no vouchers were indicated. He most likely confused Le Danios’ (1979) C. umbrinus flammeus  with C. umbrinus  , a species now considered to be endemic to the Hawaiian region.

Hutchins (2001) recorded C. cf. fimbriatus  from Western Australia but his species is most likely C. nebulosus  , described in the present study.

Chaunax penicillatus  was recorded from eastern Africa by Smith in Smith & Heemstra (1986). The vouchers were examined by the first author and the presence of this species in the Indian Ocean is confirmed. Additional specimens collected off Western Australia (deposited in AMS, NMV and CSIRO) and India (deposited in Cochin Unit, National Bureau of Fish Genetic Resources and Centre for Marine Living Resources & Ecology) were also examined by the first author.

Specimens of Chaunax russatus  Ho et al., 2013, collected from the western Indian Ocean, are also recognized in this study and the species is now thought to exhibit a trans-Indian Ocean distribution.

Consequently, at least 6 species occur in Indian Ocean: C. apus  , C. flammeus  , C. penicillatus  , C. russatus  and the two new species described herein. Other unidentified, and possibly undescribed, species have been noticed in collections that require further study.