カワビシャ科 Pentacerotidae
Armourheads
34 ミナミクサカリツボダイ（新称）
Pentaceros richardsoni
Smith, 1844 Pelagic
Armourhead
Specimens
examined: 6 (SNFR 16227–16232; 391–463 mm SL), 445–850
m depth.
Counts:
D XIII–XIV, 9–10; A IV–V, 7–9; P1 16–18;
P2 I, 5; GR 3–6+15–16=18–22; LLS 76–90; V 13+13–14=26–27. Measurements:
head length 29.5–32.6% SL; body depth 34.1–44.6% SL; eye diameter 24.3–27.2%
HL; interorbital width 25.5–33.5% HL; snout length 36.5–40.4%
HL; upper-jaw length 30.9–33.0% HL; lower-jaw length 38.6–42.5% HL;
caudal-peduncle length 53.6–60.5% HL; caudal-peduncle depth 31.4–35.3% HL;
pectoral-fin length 76.0–88.5% HL; pelvic-fin length 62.5–73.9% HL.
計数形質：背鰭13–14棘，9–10軟条；臀鰭4–5棘，7–9軟条；胸鰭16–18軟条；腹鰭1棘，5軟条；鰓耙数3–6+15–16=18–22；側線鱗数76–90；脊椎骨数13+13–14 =26–27．計測形質：頭長29.5–32.6%
SL；体高34.1–44.6% SL；眼径24.3–27.2% HL；両眼間隔25.5–33.5% HL；吻長36.5–40.4% HL；上顎長30.9–33.0% HL；下顎長38.6–42.5% HL；尾柄長53.6–60.5% SL；尾柄高31.4–35.3% HL；胸鰭長76.0–88.5% HL；腹鰭長62.5–73.9% HL.
特 徴 体は強く側扁する．胸部腹面は平坦．腹部は正中線沿いに強く隆起する．頭部は多数の溝をもつ粗雑な骨で広く覆われる．吻は尖る．口は斜め．両顎歯は鋭い小円錐歯で，歯帯をなす．眼は中庸大．背鰭は連続し，基部は長い．背鰭棘条は強大で，基部は体背縁の溝に収まる．臀鰭基底長は短い．臀鰭棘条は強大で，基部は体腹縁の溝に収まる．尾柄長は尾柄高より長い．尾鰭は截形または僅かに凹む．胸鰭は尖る．腹鰭は胸鰭よりやや短い．腹鰭棘条は強大で長い．側線は緩やかに湾曲し，尾柄部では直線状．鱗は弱い櫛鱗．項部，頬部，胸部の鱗は厚く硬い．胸部の鱗は互いに密着する．峡部と腹鰭始部との間の正中線上に29–37枚の鱗が並ぶ．体の背部は暗褐色で，腹部は淡褐色．
分 布 南半球の温帯域に広く分布する (Hardy,
1983)．
備 考 本種の体高は個体変異が大きい．本種は従来クサカリツボダイ属Pseudopentacerosに含められていたが (e.g.,
Hardy, 1983)，Kim (2012) はPseudopentacerosをツボダイ属Pentacerosのシノニムとした．本種は北太平洋のクサカリツボダイPentaceros wheeleri
(Hardy, 1983) とは，峡部と腹鰭始部との間の正中線上に並ぶ鱗が多い（29–39
vs. 22–29）こと等により区別される
(Hardy, 1983)．Abe
(1953) は日本初の
P. wheeleri （その時点では未記載種）を本種に同定し，クサカリツボダイの和名を与えた．Hardy
(1983) は北半球産のクサカリツボダイ類を南半球産の本種とは別種と考え，2新種P. wheeleriおよびP. pectoralis
として記載した（のちに後者は前者のシノニムとされた:
Humphery et al.
[1989]）．そのため本種に該当する標準和名が失われたことから新称を提唱する．Hardy
(1990) は本種に和名クサカリツボダイを当てたが，この和名は正しくない．
(星野)
Description Body
strongly laterally compressed. Breast flat ventrally. Belly strongly keeled
along mid-ventral line. Head predominantly covered with rugose,
striated bones. Snout pointed. Mouth oblique. Teeth on both jaws short, conical,
sharp, set in band. Eye moderate in size. Dorsal fin continuous, its base long.
Dorsal-fin spines robust, their bases embedded in a prominent groove. Anal-fin
base short. Anal-fin spines robust, their bases embedded in a prominent groove.
Caudal peduncle longer than deep. Caudal fin truncate or slightly emarginate. Pectoral fin pointed. Pelvic fin slightly
shorter than pectoral fin. Pelvic-fin spine robust and long. Lateral line
gently arched, straight at caudal peduncle. Scales weakly
ctenoid; those of nape, cheek, and breast thick; those
on throat and breast juxtaposed; 29–37 scales
from isthmus to level of pelvic-fin origin. Body dark brown dorsally, light
brown ventrally.
Distribution Widely
distributed in temperate waters in Southern Hemisphere (Hardy, 1983).
Remarks The
body depth of this species is somewhat variable. This species was previously
included in the genus Pseudopentaceros
(e.g., Hardy, 1983), but Kim (2012) relegated this genus to a junior synonym of
Pentaceros.
This species differs from the North Pacific congener, Pentaceros wheeleri (Hardy, 1983) in having more
scales on the midline between the isthmus and the pelvic-fin origin (29–39 vs.
22–29) (Hardy, 1983). Abe (1957) identified the first specimens of P. wheeleri
(an undescribed species then) from
(K. Hoshino)