Symbiotic copepods (Cyclopoida and Siphonostomatoida) collected by light trap from Korea
Author
Lee, Jimin
https://orcid.org/0000-0001-9004-8275
Marine Ecosystem and Biological Research Center, Korea Institute of Ocean Science & Technology, Busan 49111, Republic of Korea
Author
Chang, Cheon Young
https://orcid.org/0000-0001-5557-7120
Department of Biological Science, Daegu University, Gyeongsan 38453, Republic of Korea
Author
Kim, Il-Hoi
https://orcid.org/0000-0002-7332-0043
Korea Institute of Coastal Ecology, 302 - 802, Seokcheon-ro 397, Bucheon 14449, Republic of Korea
ihkim@gwnu.ac.kr
text
ZooKeys
2022
2022-07-28
1115
1
71
http://dx.doi.org/10.3897/zookeys.1115.83266
journal article
http://dx.doi.org/10.3897/zookeys.1115.83266
1313-2970-1115-1
C3E233F10EF74D2DBD4AA32AE7C4DF5E
1AB765B8065B5504A31014D2B0937E01
Eupolymniphilus foliatus
sp. nov.
Figs 22
, 23
, 24
Material examined.
Holotype
♀
(MABIK CR00250130) and
paratype
♂
dissected and mounted on a slide, and intact
paratypes
2 ♂♂
(MABIK CR00250122) preserved in 90% alcohol,
Site
2 (
Namyang
,
Ulleung Island
,
Sea
of
Japan
,
37°28'01.3"N
,
130°50'01.4"E
),
01 Jul. 2021
, leg.
J. G. Kim. Dissected
paratype
(
♂
) is retained in the collection of
I.-H. Kim.
Description.
Female.
Body (Fig.
22A
) moderately broad. Body length 1.44 mm. Prosome 840
x
586
μm
, fusiform. Cephalothorax with dorsal suture line delimiting cephalosome and first pedigerous somite. Second to fourth pedigerous somites bearing angular posterolateral corners. Urosome (Fig.
22B
) five-segmented. Fifth pedigerous somite expanded laterally, wider than genital double-somite, with sleeve-like, pronounced posterolateral corners. Genital double-somite longer than wide (210
x
184
μm
), with convex lateral margins, widest at 45% region of double-somite. Three free abdominal somites 59
x
106
μm
, 45
x
95
μm
, and 80
x
91
μm
, respectively. Anal somite unornamented, lacking any spinules. Caudal ramus (Fig.
22C
) 3.33
x
longer than wide (130
x
39
μm
), ~ 1.6
x
longer than anal somite, armed with six setae; seta II slightly expanded along proximal third, positioned dorsally at 56% region of ramus length.; setae IV-VI pinnate, other setae naked.
Figure 22.
Eupolymniphilus foliatus
sp. nov., female
A
habitus, dorsal
B
urosome, dorsal
C
left caudal ramus, dorsal
D
rostrum
E
antennule
F
antenna
G
labrum
H
mandible
I
maxillule
J
maxilla. Scale bars: 0.2 mm (
A
); 0.1 mm (
B
); 0.05 mm (
C-G
); 0.02 mm (
H-J
).
Rostrum (Fig.
22D
) well-developed, slightly wider than long, with blunt apex. Antennule (Fig.
22E
) 340
μm
long, seven-segmented; first and second segments broader than distal segments; armature formula 4, 13, 6, 3, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; all setae naked; third and terminal segments equally short. Antenna (Fig.
22F
) four-segmented; armature formula 1, 1, 3+claw, and 4+3 claws; terminal segment (third endopodal segment) 2.65
x
longer than wide (61
x
23
μm
); claws on third and terminal segments slender, setiform; apical seta on terminal segment distinctly longer than other setae on same segment; innermost of three claws on terminal segment shorter than others.
Labrum (Fig.
22G
) with distinctly defined, divergent posterolateral lobes and broad posteromedian incision. Mandible (Fig.
22H
) with gnathobase bearing finely denticulate convex outer margin, ~ 15 unequal spinules along concave inner margin, and distal lash fringed with wrinkled membrane along outer margin and narrow membrane along inner margin; inner proximal region of gnathobase lacking notch; outer proximal region of blade with one small, indistinct scale. Maxillule (Fig.
22I
) lobate, with one expanded, leaf-like, modified seta on inner margin and three (one longer and two shorter) apical setae. Maxilla (Fig.
22J
) two-segmented; proximal segment (syncoxa) unarmed; distal segment (basis) distally with five spinules followed by three larger spinules and slender, spinulose lash, and armed with three setae (seta I-III); seta I (inner seta) large, spinulose along distal (outer) margin; seta II (anterior seta) slightly broadened, with acute distal tip; seta III (outer proximal seta) rudimentary. Maxilliped (Fig.
23A
) three-segmented; first segment unarmed; second segment with two unequal setae subdistally; third segment narrow, pointed distally, with one small, subdistal seta.
Figure 23.
Eupolymniphilus foliatus
sp. nov., female
A
maxilliped
B
leg 1
C
leg 2
D
third endopodal segment of leg 3
E
leg 4
F
left leg 5 and genital aperture. Scale bars: 0.02 mm (
A
); 0.05 mm (
B-F
).
Legs 1-4 (Fig.
23B-D
) biramous with three-segmented rami; outer seta on basis small, naked. Inner coxal seta of all swimming legs well-developed, pinnate. Armature formula for legs 1-4 as follows:
| - |
Coxa |
Basis |
Exopod |
Endopod |
| Leg 1 |
0-1 |
1-0 |
I-0; I-1; III, I, 4 |
0-1; 0-1; I, 1, 4 |
| Leg 2 |
0-1 |
1-0 |
I-0; I-1; III, I, 5 |
0-1; 0-2; I, II, 3 |
| Leg 3 |
0-1 |
1-0 |
I-0; I-1; III, I, 5 |
0-1; 0-2; I, II, I+2 |
| Leg 4 |
0-1 |
1-0 |
I-0; I-1; II, I, 5 |
0-1; 0-1; I, II, II |
Leg 5 (Fig.
23F
) consisting of one small dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment small, 1.59
x
longer than wide (46
x
29
μm
), widest at proximal third, narrowing distally, armed with one seta (60
μm
long) and one elongate compound spine (117
μm
long). Leg 6 (Fig.
23F
) represented two small setae and single denticle on genital operculum
Male.
Body (Fig.
24A
) narrower and smaller than that of female. Body length 847
μm
in dissected paratype (length range 782-847
μm
). Prosome 495
x
287
μm
. Urosome (Fig.
24B
) six-segmented. Fifth pedigerous somite 109
μm
wide, lacking posterolateral sleeve-like extension seen in female. Genital somite subquadrate, 127
x
124
μm
, with rounded anterolateral corners and pointed posterolateral corners; genital operculum with pointed apex. Four abdominal somites 36
x
60
μm
, 29
x
55
μm
, 22
x
51
μm
, and 36
x
56
μm
, respectively. Caudal ramus 2.40
x
longer than wide (60
x
25
μm
), armed as in female.
Figure 24.
Eupolymniphilus foliatus
sp. nov., male
A
habitus, dorsal
B
urosome, dorsal
C
maxillule
D
maxilliped. Scale bars: 0.1 mm (
A
); 0.05 mm (
B
); 0.02 mm (
C, D
).
Rostrum as in female. Antennule as in female, but with three additional aesthetascs at places of dark circles in Fig.
21E
. Antenna, labrum, mandible as in female. Maxillule (Fig.
24C
) with less expanded inner margin seta. Maxilla as in female. Maxilliped (Fig.
24D
) consisting of three segments and terminal claw; first segment with one large tubercle at inner subdistal region; second segment with two unequal setae and one longitudinal row of spinules; small third segment unarmed; terminal claw elongate, as long as three segments, arched, bearing one setule and one large, slightly undulated seta proximally.
Legs 1-5 as in female. Leg 6 represented by two small setae on genital operculum (Fig.
24B
).
Etymology.
The specific name of the new species is from Latin
foli
(a leaf), alluding to the leaf-like inner seta of the maxillule.
Remarks.
Differences between species of
Eupolymniphilus
are slight. However,
E. foliatus
sp. nov. can be differentiated from its congeners by the key character, the leaf-like modified inner seta of the maxillule. This seta in other species of the genus is known to be simple and slender. Another characteristic feature of the new species is the presence of thick membranes on the distal part of the mandibular lash.
The length-to-width ratio of the caudal ramus in
Eupolymniphilus
is somewhat variable among congeneric species. In the female, it is 3.5:1 in
E. finmarchicus
(Scott T., 1903) according to the illustration of G. O.
Sars (1918)
, ~ 10:1 in
E. tenuicaudis
(G. O. Sars, 1918), 1.50:1 in
E. orientalis
Kim, 2006, 1.03:1 in
E. brevicaudatus
Kim, 2009, 2.69:1 in
E. occidentalis
Kim, 2009, and 3.05:1 in
E. mediterraneus
Costanzo, Brugnano & Zagami, 2013. Thus,
E. foliatus
sp. nov., in which the caudal ramus is 3.33
x
longer than wide, is comparable to the three species,
E. finmarchicus
,
E. occidentalis
, and
E. mediterraneus
. Furthermore, they differ from the new species, as follows:
E. finmarchicus
has five setae on the first segment of the antennule (
Bocquet et al. 1963
), and the mandible lacks any outer scale;
E. occidentalis
has acutely pointed posterolateral corners on the second pedigerous somite (cf. with blunt posterolateral corners in
E. foliatus
sp. nov.), seven aesthetascs on the male antennule (cf. six aesthetascs in
E. foliatus
sp. nov.), and a shorter terminal segment of the antenna which is 1.92
x
longer than wide according to
Kim (2009)
(cf. 2.65
x
longer than wide in
E. foliatus
sp. nov.); and
E. mediterraneus
has a small body size, 0.75 mm in the female, and the terminal segment of the antenna bears four claws (
Costanzo et al. 2013
) (cf. three claws in
E. foliatus
sp. nov.).