Liocranium Ogilby

Motomura, Hiroyuki, Last, Peter R. & Johnson, Jeffrey W., 2008, Review of the waspfish genus Liocranium (Scorpaeniformes: Tetrarogidae), with restoration of L. pleurostigma (Weber), Zootaxa 1820, pp. 27-40 : 28-30

Genus Liocranium Ogilby

Liocranium Ogilby, 1903: 23 (type species: Liocranium praepositum Ogilby, 1903 ). Abcichthys Whitley, 1927: 304 (unnecessary replacement name for Liocranium ).

Diagnosis. A genus of the family Tetrarogidae with the following combination of characters: dorsal-fin origin distinctly anterior to a vertical from posterior margin of orbit; dorsal fin continuous, anterior 3 spines not forming a nearly separate fin; 13 dorsal-fin spines; 8 (rarely 7 or 9) dorsal-fin soft rays; 14 (rarely 13 or 15) pectoral-fin rays; 4 pelvic-fin soft rays; 5 or 6 anal-fin soft rays; palatine teeth absent; 12–17 short gill rakers; numerous small cycloid scales covering lateral surface of body; body depth 39–46% of SL.

Description. Dorsal fin with 13 spines and 8 (rarely 7 or 9) soft rays; all soft rays branched; third spine longest, its length longer than second anal-fin spine length; third to seventh spines progressively shorter, seventh to twelfth spine progressively longer; length of twelfth spine subequal to last spine; distance between bases of third and fourth spines greatest, more than twice distance between bases of seventh and eighth spines; membrane of spinous portion of dorsal fin strongly notched; first and second soft rays equally longest, their length slightly longer than that of longest dorsal-fin spine; posterior branch of last soft ray joined by membrane to caudal peduncle for approximately half or more its length. Anal fin with 3 spines and 5 or 6 soft rays; third spine longest; all soft rays branched; first or second soft ray longest, its length greater than that of longest spine; posterior branch of last soft ray joined by membrane to caudal peduncle for more than half (rarely less than half) its length. Pectoral fin with 14 (rarely 13 or 15) rays on each side of body; sixth ray longest, its length subequal to head length; lower unbranched rays somewhat thickened; posterior margin of fin rounded. Pelvic fin with a spine and 4 soft rays, all soft rays branched (rarely last ray unbranched); first soft ray longest, its length longer than upper-jaw length; posterior margin of last soft ray joined by relatively thick membrane to abdomen for more than four-fifths its length. Caudal fin with 14 segmented rays, 11 or 12 rays branched, remaining distal rays unbranched; 3 dorsal and 3 ventral series of procurrent rays; caudal-fin length shorter than pectoral-fin length; posterior margin of fin rounded.

Pored lateral-line scales 19–22. Predorsal scales absent. Gill rakers 12–17, remarkably short, spinous, rudimentary; length of longest raker on first gill arch approximately equal to that of gill filaments around angle of gill arch; fourth gill slit closed by membrane. Uppermost parts of dorsal-fin pterygiophores, between third and fourth, and fourth and fifth spines, not in contact with each other. Vertebrae 26. Swimbladder absent.

Body strongly compressed anteriorly, progressively more compressed posteriorly; nape and anterior body arched; body depth subequal to head length. No tentacles, cirri or skin flaps on surface of head, trunk and fins, except on nasal openings. A short, slender tentacle on dorsal edge of low membranous tube associated with anterior nostril. Posterior lacrimal spine joined by relatively thick membrane posteriorly to head.

Exposed cycloid scales or scales embedded by thin skin on lateral surface of trunk; scales embedded by relatively thick skin on pectoral-fin base and ventral surface of trunk; scales not extending onto rays or membranes of fins, except basally on caudal fin. No scales on head. Lateral line not strongly sloping downward, nearly straight above pectoral fin. No small papillae on surface of head and eye membrane. Small number of small sensory pores scattered on surface of head. Anterior and posterior nasal openings subequal in diameter; distance between anterior and posterior nostrils subequal to nostril diameter; posterior nostril located at anteroventral edge of orbit. A remarkably large pore behind symphysial knob and an indistinct pore on each side of symphysial knob of lower jaw in ventral view. Underside of dentary with 3 well-developed sensory pores on each side, first pore below base of anterior lacrimal spine, second pore below tip of anterior lacrimal spine, third pore located on posterior margin of dentary.

Mouth relatively small, slightly oblique, forming an angle of about 20 degrees to horizontal axis of head and body. No longitudinal ridge on lateral surface of maxilla. Lower jaw with a symphysial knob. Width of symphysial gap separating premaxillary teeth bands subequal to or less than width of each band; upper jaw with a band of villiform teeth; tooth band narrowing posteriorly. Width of symphysial gap separating lower jaw teeth bands narrower than width of each band; lower jaw with a band of villiform teeth; lengths of most teeth subequal to those of upper jaw. Vomer with villiform teeth. No palatine teeth. Underside of lower jaw without ridges.

Dorsal profile of snout steep, forming an angle of about 60 degrees to horizontal axis of head and body. Nasal spine absent. Ascending process of premaxilla slightly intruding into interorbital space, its posterior margin reaching anterior margin of orbit in lateral view. Interorbital ridges very weakly developed, beginning behind posterior margin of ascending process of premaxilla and then conjoined to each other at level of anterior margin of pupil. Interorbital space convex. No median interorbital ridge. No spines on interorbital space or around orbit. Supracleithral spine embedded in thick skin. No spine projecting from opercle. Cleithral spine flattened, covered with skin. Upper end of gill opening just reaching a horizontal line through middle of eye.

Lateral surface of lacrimal smooth, without spines and ridges. Anterior lacrimal spine simple, directed ventroposteriorly, its tip extending well beyond dorsal margin of upper lip. Posterior lacrimal spine simple, directed posteriorly, its tip not reaching upper lip; its length more than twice length of anterior lacrimal spine. Suborbital ridge without spines. Space between ventral margin of eye and suborbital ridge narrow. Suborbital pit absent. Preopercle with 5 spines; uppermost spine largest, sharp, with narrow base, lacking a supplemental preopercular spine on its base; second to fifth spines with broad base, lacking a median ridge; spines entirely covered with skin. Preopercle between uppermost preopercular spine and upper end of preopercle, without serrae or spines.

Origin of first dorsal-fin spine above anterior margin of pupil; origin of second spine above middle of pupil; origin of third spine behind vertical from posterior margin of orbit; origin of fourth spine above tip of preopercular spine. Posterior tip of opercular membrane extending well beyond a vertical through fifth dorsalfin spine base. Origin of pelvic-fin spine slightly posterior to origin of uppermost pectoral-fin ray. Origin of first anal-fin spine anterior to origin of last dorsal-fin spine.

Remarks. The genus Liocranium was proposed by Ogilby (1903) as monotypic for his new species, L. praepositum Ogilby, 1903 , described from Queensland, Australia. McCulloch (1921) included Paracentropogon scorpio Ogilby, 1910 in Liocranium , as the second species of the genus. However, Whitley (1933) proposed a new genus, Vadesuma , for P. s c o r p i o. Mees (1964b) placed P. s c o r p i o in Liocranium . Paracentropogon scorpio is currently recognized as a junior synonym of Cottapistus cottoides Linnaeus, 1758 (e.g., Eschmeyer, 1998), although some authors (e.g., Allen & Cross, 1989; Hutchins, 2001) regarded the former as a valid sibling species. Accordingly, Vad e su ma is a junior synonym of Cottapistus Bleeker, 1876 . Careful comparisons are required to assess validity of C. scorpio but these forms differ markedly in body and caudal fin coloration.

Whitley (1927) thought that Liocranium was preoccupied by the spider genus Liocranum and proposed a new replacement name, Abcichthys , for Liocranium . McCulloch (1929) followed the replacement name and recognized two species, A. praepositum and A. scorpio . However, spellings of Liocranium and Liocranum are distinct; thus Abcichthys was unnecessary as a replacement name and is an objective synonym of Liocranium .

Weber (1913) described two new species, Paracentropogon pleurostigma and P. cynocephalus , from the vicinity of New Guinea. Subsequently, de Beaufort (1949) proposed a new genus, Sibogapistus , for P. cynocephalus (type species) and included P. pleurostigma in the genus. Mees (1964b) recognized P. cynocephalus as a junior synonym of L. scorpio on the basis of his examination of type specimens. Accordingly, Sibogapistus is a junior synonym of Cottapistus (because L. scorpio is a junior synonym of C. cottoides , the type species of Cottapistus ; see above).

Mees (1964a, b) recognized Liocranium as a valid genus and included two species, one of which with two subspecies in the genus ( L. praepositum praepositum , L. p. pleurostigma and L. scorpio ). Subsequently, Gloerfelt-Tarp & Kailola (1984) and Sainsbury et al. (1985) also regarded Liocranium as valid. More recently, Allen & Cross (1989), Allen et al. (1997) and Hutchins (2001, 2003) treated Liocranium as a junior synonym of Cottapistus , whereas Larson & Williams (1997) and Poss (1999) regarded Liocranium as valid. We agree with Poss’ (1999) concept of tetrarogid genera. Liocranium is easily distinguished from Cottapistus by overall body appearance (high body depth and short snout in Liocranium vs. elongate body and long snout in Cottapistus ), by having 13 dorsal-fin spines (vs. 14 or 15 in the latter), scales covering entire lateral surface of trunk (vs. scales lacking on anterior part of trunk above opercle), and narrow interorbital space, its width less than orbit diameter (vs. wide space, exceeding orbit diameter). In his key to the genera and species of Indo – Pacific scorpionfishes, Poss (1999) separated Liocranium from Cottapistus by several characters, including number of pelvic-fin soft rays (4 vs. 5), but in fact both genera have 4 rays.

Eschmeyer et al. (1973) and Motomura & Senou (2005) reported the shedding of cuticle in the scorpionfish genera Rhinopias and Hipposcorpaena , respectively. Cuticle in the process of shedding on the surface of the body was also found in several specimens of Liocranium pleurostigma and L. praepositum . Motomura & Johnson (2006) presumed that the irregularity of the scale rows and indistinct scale contours in Rhinopias may be related to the epidermal structure associated with shedding. That is also applicable to Liocranium .