A New Species of the Enigmatic Copepod Genus Lernaeascus (Cyclopoida: Philichthyidae), Parasitic on Angelfishes (Actinopterygii: Pomacanthidae) from the Ryukyu Islands, Japan
Author
Uyeno, Daisuke
Florida Museum of Natural History, University of Florida, 1659 Museum Rd., Gainesville, Florida 32611, USA E-mail: daisuke. uyeno @ gmail. com & Current affiliation: Graduate School of Science and Engineering, Kagoshima University, 1 - 21 - 35 Korimoto, Kagoshima 890 - 0065, Japan E-mail: daisuke. uyeno @ gmail. com
daisuke.uyeno@gmail.com&daisuke.uyeno@gmail.com
Author
Tang, Danny
Environmental Laboratory and Ocean Monitoring Division, Orange County Sanitation District, 10844 Ellis Avenue, Fountain Valley, California 92708 - 7018, USA
Author
Nagasawa, Kazuya
Graduate School of Biosphere Science, Hiroshima University, 1 - 4 - 4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739 - 8528, Japan
text
Species Diversity
2015
2015-11-25
20
159
166
journal article
3237
10.12782/sd.20.2.159
6c0f25ec-12e0-4544-9080-a49ffd6a5f8c
2189-7301
5737533
Lernaeascus kabuto
sp. nov.
(
Figs 1–4
)
Type material.
Holotype
male (NSMT-Cr 24277) and
allotype
female (NSMT-Cr 24278), ex
Centropyge venusta
(Yasuda and Tominaga)
(
Perciformes
:
Pomacanthidae
), East
China
Sea, off Torishima Islet (
26°19′N
,
126°49′E
), Kumejima Island, Ryukyu Islands,
Japan
,
40 m
depth,
19 November 2009
, leg. D. Uyeno.
Paratypes
:
2 males
and
1 female
(NSMT-Cr 24279), collection data as for
holotype
and
allotype
;
1 male
(KAUM-AT-211), collection data as for
holotype
and
allotype
;
1 male
(NSMT-Cr 24280), ex
C. heraldi
Woods and Schultz
(
Perciformes
:
Pomacanthidae
), East
China
Sea, off Torishima Islet (
26°5′N
,
127°42′E
), Kumejima Island, Ryukyu Islands,
Japan
,
8 m
depth,
16 November 2009
, leg. D. Uyeno;
1 male
(
RUMF-ZC
03913), ex
C. venusta
, East
China
Sea, off Shichugama (
26°20′N
,
126°50′E
), Kumejima Island, Ryukyu Islands,
Japan
,
15 m
depth,
25 August 2010
, leg. D. Uyeno, Y. Fujita and I. Nakayoshi.
Description of
holotype
male.
Body (
Fig. 1A
) dorsoventrally compressed, 1179 long (including caudal rami), composed of 11 somites. Cephalosome (
Fig. 1A
) subquadrate, slightly constricted at mid-length, longer than wide 273×222. Second pedigerous somite (
Fig. 1B
) bearing paired wing-like dorsal plates, each with inner subterminal notch. Urosome 586 long, composed of fifth pediger, genital somite, and four abdominal somites. Genital somite wider than long 79×132. Third abdominal somite (
Fig. 1D
) bearing dorsal hamulus on each posterolateral corner. Caudal ramus (
Fig. 1D
) bearing six setae.
Antennule (
Fig. 1E
) 4-segmented; proximal segment robust, elongate and anteriorly curved; armature formula 12, 3, 2+1 aesthetasc, 7+1 aesthetasc. Antenna (
Fig. 1F, G
) 4-segmented, consisting of coxobasis and 3-segmented endopod; coxobasis rod-like, unarmed; proximal endopodal segment rod-like, bearing three small and three large, highly sclerotised, squamate denticles on anterior surface; middle endopodal segment small, bearing large claw-like spine, seta, and large denticulate process; terminal endopodal segment bearing three claw-like spines and three setae on tip. Labrum (
Fig. 2A
) broad, slightly indented in middle of posterior margin. Mandible (
Fig. 2A
) unsegmented, bearing serrate apical blade. Paragnath absent. Maxillule (
Fig. 2A
) small, conical, with subterminal process and blunt tip. Maxilla (
Fig. 2A
) 2-segmented, comprising syncoxa and basis; syncoxa robust and elongate; basis represented by terminal blade with serrate anterior margin. Maxilliped absent.
Legs 1 and 2 (
Fig. 2B, D
) biramous, composed of coxa, basis, 2-segmented exopod, and spiniform endopod; armature formula of legs shown in
Table 1
. First exopodal segment of legs 1 and 2 (
Fig. 2C, E
) ornamented with small process on outer margin. Endopods of legs 1 and 2 (
Fig. 2B, D
) rudimentary, each represented by robust spine. Leg 3 (
Fig. 2F
) fused to third pediger, comprising two basal setae and unsegmented, exopod armed with two long, simple terminal setae. Legs 4 and 5 absent. Leg 6 (
Fig. 1C
) represented by posteroventral genital operculum (
Fig. 1C
), armed with minute subterminal seta.
Variability of male morphology.
Morphology of body parts of
paratypes
as in
holotype
. Measurements of body parts of
paratypes
(n=5) as follows: body length 1037–1375 (1206±144); cephalosome length 225–346 (294±50); cephalosome width 159–335 (268±74); urosome length 518–658 (570±68); genital somite length 68–84 (78±6); genital somite width 107–146 (131±15).
Description of
allotype
female.
Body (
Fig. 3A
) vermiform, 2210 long (including caudal rami), composed of cephalosome and trunk. Cephalosome (
Fig. 3B, F
) conical, longer than wide 234×159, with blunt frontal margin, having elliptical corrugated pad on dorso-apical surface and corrugated surface medial and lateral to antenna. Trunk (
Fig. 3A, C
) slightly curved, terminating in small abdomen, ornamented with longitudinal dorsal rows of serrate, crescentic plates on right side and patch of dorsal corrugations near posterior end. Genital field (
Fig. 3D
) with laterally paired copulatory pores. Caudal ramus (
Fig. 3C, E
) fused with abdomen, bearing five setae.
Antennule (
Fig. 3G
) 2-segmented; proximal segment longest and slightly constricted at mid-length; armature formula 17+1 aesthetasc, 6+1 aesthetasc. Antenna (
Fig. 3F, H
) apparently 1-segmented, arising from mid-ventral surface of cephalosome, triangular with medial conical process, lateral digitate process, and apical spine. Labrum (
Fig. 4A
) with broad base produced into postero-median styliform process. Mandible (
Fig. 4A
) unsegmented, bearing serrate apical blade. Paragnath and maxillule absent. Maxilla (
Fig. 4A
) 2-segmented; proximal segment (syncoxa) triangular, unarmed; terminal segment (basis) armed with 2 subequal serrate blades. Maxilliped absent.
Legs 1 and 2 (
Fig. 4B, C
) each comprising knob-like protopod carrying lateral seta and rod-like, 1-segmented exopod, latter bearing three distal setae on leg 1 and single medial and two distal setae on leg 2. Leg 3 (
Fig. 4D
) vestigial, represented by two setae. Legs 4 and 5 absent.
Fig. 1.
Lernaeascus kabuto
sp. nov.
, adult male, holotype (NSMT-Cr 24277). A, Habitus, dorsal; B, prosomites 2–5, dorsal; C, right side of genital somite, ventral; D, posterior part of urosome, dorsal; E, frontal region of cephalothorax and right antennule, ventral; F, right antenna, lateral; G, same, posterior. Scale bars: 200 µm for A; 100 µm for B; 50 µm for C; 30µm for D–G.
Fig. 2.
Lernaeascus kabuto
sp. nov.
, adult male, holotype (NSMT-Cr 24277). A, Mouth parts (mn, right mandible; m1, right maxillule; m2, right maxilla), ventral; B, right leg 1, anterior; C, exopod of right leg 1, posterior; D, right leg 2, anterior; E, exopod of right leg 2, posterior; F, right leg 3, ventral. Scale bars: 40 µm for A; 50µm for B, D; 30 µm for C, E, F.
Variability of female morphology.
Morphology of body parts of
paratype
as in
allotype
. Measurements of
paratype
(n=1) as follows: body length 1964; cephalosome length 217; cephalosome width 118.
Etymology.
The specific name
kabuto
, a noun in apposition, the Japanese name for the helmets worn by Japanese warlords and alludes to the shape of the male cephalothorax and the associated curved, elongate antennules.
Infection site.
Unknown.
Remarks.
The new species is included in
Lernaeascus
, as it shares a number of characters in common with
L. nematoxys
, such as a vermiform body in females that is composed of a cephalosome, a long trunk embossed with multiple rows of scale-like cuticular structures, and a short abdomen and in males a pair of dorsal plates on the second pediger.
Lernaeascus kabuto
sp. nov.
is easily distinguishable from
L. nematoxys
by differences in (1) the proportions, segmentation, and ornamentation of the urosomites and the structure of the dorsal plates, antennule, labrum, maxillule, maxilla, leg 1, and leg 6 of the male, as well as (2) the ornamentation of the cephalosome and structure of the antenna, labrum, and first two pairs of legs of the female (
Table 2
).
Fig. 3.
Lernaeascus kabuto
sp. nov.
, adult female, allotype (NSMT-Cr 24278) (A–D, F, G) and paratype (NSMT–Cr 24279) (E, H). A, Habitus, dorsal; B, anterior part of body, dorsal; C, posterior part of trunk, dorsal with, arrowhead indicating position of copulatory pores; D, same, lateral; E, caudal rami, dorsal; F, head region, ventral; G, right antennule, posterior; H, right antenna, posterior. Scale bars: 400µm for A; 100µm for B–D, F; 30 µm for E; 20µm for G, H.
Fig. 4.
Lernaeascus kabuto
sp. nov.
, adult female, allotype (NSMT-Cr 24278). A, Mouth parts (lbr, labrum; mn, right mandible; m2, right maxilla), ventral; B, right leg 1, anterior; C, right leg 2, anterior; D, right leg 3, anterior. Scale bars: 20 µm for A; 10 µm for B–D.
Table 1. Armature formulae of legs 1 and 2 of
Lernaeascus kabuto
sp. nov.
, holotype, adult male, NSMT-Cr 24277. Arabic numerals refer to the number of setae, Roman numerals refer to the number of spines.
| Coxa |
Basis |
Exopod |
Endopod |
| Leg 1 |
0–0 |
1–0 |
I–0; III, I, 1 |
I |
| Leg 2 |
0–0 |
1–0 |
I–0; II, I, 1 |
I |
Newly established Japanese name for both the genus and the species.
Senchu-modoki