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Submitted 1 November 2022
Accepted 22 January 2023
Published 21 February 2023
Corresponding author
Taekjun Lee, leetj@syu.ac.kr
Academic editor
Federica Semprucci
Additional Information and
Declarations can be found on
page 24
DOI 10.7717/peerj.14889
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2023 Kim and Lee
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Two new genera and four new species of
Asterocheridae
(Copepoda: Siphonostomatoida)
associated with sponges (Porifera) from
the Korean East Sea
Il-Hoi Kim1and Taekjun Lee2,3
1Korea Institute of Coastal Ecology, Bucheon, South Korea
2Department of Animal Resources Science, Sahmyook University, Nowon-gu, Seoul, South Korea
3Marine Biological Resource Institute, Sahmyook University, Nowon-gu, Seoul, South Korea
ABSTRACT
Two new genera and four new species of siphonostomatoid copepods of the family
Asterocheridae associated with sponges are described from the Korean East Sea (Sea
of Japan). These new copepods are distinguishable from related genera and species by
their diagnostic morphological characters as follows: Amalomyzon elongatum n. gen. n.
sp. bears an elongated body, two-segmented rami of legs 2, a uniramous leg 3 with two-
segmented exopod, and a rudimentary leg 4 represented by a lobe. Dokdocheres rotundus
n. gen. n. sp. has an 18-segmented female antennule, a two-segmented endopod of
antenna, and unusual setations of swimming legs, including three spines plus four
setae on the third exopodal segment of legs 2–4. Asterocheres banderaae n. sp. has no
inner coxal seta on leg 1 or 4, but has two strong, sexually dimorphic inner spines on
the second endopodal segment of male leg 3. Scottocheres nesobius n. sp. bears elongate
female caudal rami about six times longer than wide, a 17-segmented female antennule,
and two spines plus four setae on the third exopodal segment of leg 1.
Subjects Biodiversity, Marine Biology, Taxonomy, Zoology
Keywords Amalomyzon n. gen., Dokdocheres n. gen., Asterocheres,Scottocheres, Taxonomy
INTRODUCTION
Siphonostomatoid copepods of the family Asterocheridae live in association with marine
invertebrates. The most commonly reported hosts of these copepods are sponges,
cnidarians, and echinoderms, although hosts are unknown for many species of copepods
(Boxshall & Halsey, 2004). The great majority of the copepods of this family have been
recorded from European and tropical seas with very few recorded in the entire Pacific
region. Ho (1984) was the first one who recorded a species of the Asterocheridae in the
Korean East Sea (Sea of Japan), who described Asterocheres aesthetes as a new species
associated with sponge Spirastrella insignis Thiele, 1898 in Sado Island, Japan. Since then,
seven additional species have been reported from the same sea (three associated with
sponges, two with sea stars, and two with unknown hosts) (Table 1).
How to cite this article Kim I-H, Lee T. 2023. Two new genera and four new species of Asterocheridae (Copepoda: Siphonostomatoida)
associated with sponges (Porifera) from the Korean East Sea. PeerJ 11:e14889 http://doi.org/10.7717/peerj.14889
Table 1 Species of the family Asterocheridae recorded previously in the Korean East Sea.
Species Hosts Sources
Asterocheres aesthetes Ho, 1984 The sponges Spirustrella insignis Thiele, 1898 and Suberites
ficus (Johnston, 1842)
Ho (1984) and Kim (1998)
Asterocheres cuspis Kim, 2016 A sponge of Myxila sp. Kim (2016)
Asterocheres lilljeborgi Boeck, 1859 The sea star Henricia leviuscula (Stimpson, 1857) Kim (2016)
Asterocheres simulans (Scott, 1898) An unidentified sponge Kim (2016)
Asteropontoids acutirostris Kim, 2016 Host unknwon Kim (2016)
Callomyzon macrocephalum Kim, 2016 A Sponge epibiotic on the scallop Azumapecten farreri
(Jones & Preston, 1904)
Kim (2016)
Dermatomyzon nigripes (Brady & Robertson, 1880) Host unknown Kim (1998)
Scottomyzon gibberum (Scott & Scott, 1894) Various species of sea stars Kim (1992)
In the present article, two new genera and four new species of the Asterocheridae are
described as associates of sponges in the Korean East Sea.
MATERIALS & METHODS
The copepods studied in the present work were extracted from sponges collected at Ulleung
Island and Dokdo Island, the most remote islands of Korea located in the Korean East Sea
(Sea of Japan) (Fig. 1). Sponge hosts were collected by trimix and SCUBA diving at depths
of 22 m to 45.2 m. Copepods extracted from these sponge hosts were preserved in 80%
ethanol. Permits for marine organisms collection and export were given by the county office
of Ulleung-gun, Korea. For microscopic observation, copepods were immersed in lactic
acid for at least 10 min and dissected. Dissected appendages were observed using the reverse
slide method of Humes & Gooding (1964). Drawings were made under a light microscope
equipped with a drawing tube. In the armature formula for the description of species,
Roman numerals indicate spines and Arabic numerals represent setae. Lengths of copepod
specimens and measurements of appendages were mostly based on a dissected and figured
specimen of each species. Morphological terminology followed Huys & Boxshall (1991).
Type specimens have been deposited in the National Institute of Biological Resources
(NIBR), Incheon, Korea.
This published work and nomenclatural acts it contains have been registered in
ZooBank, an online registration system for the ICZN. The ZooBank LSIDs (Life Science
Identifiers) can be resolved and the associated information can be viewed through any
standard web browser by appending the LSID to the prefix http://zoobank.org/. The
LSID for this publication is: [urn:lsid:zoobank.org:pub:0E84F5CE-D4C5-4AAD-A72C-
CCBD77806CDB]. The online version of this work is archived and available from the
following digital repositories: PeerJ, PubMed Central SCIE and CLOCKSS.
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 2/26
Figure 1 Map showing collection localities. (A) Ulleung Island. (B) Dokdo Island.
Full-size DOI: 10.7717/peerj.14889/fig-1
RESULTS & DISCUSSION
Taxonomy
Phylum Arthropoda von Siebold, 1848
Subphylum Crustacea Brünnich, 1772
Superclass Multicrustacea Regier, Shultz, Zwick, Hussey, Ball, Wetzer,
Martin & Cunningham, 2010
Class Copepoda Milne Edwards, 1840
Order Siphonostomatoida Burmeister, 1835
Family Asterocheridae Giesbrecht, 1899
Amalomyzon n. gen.
urn:lsid:zoobank.org:act:214F5279-8986-4F6A-A32E-FD3BCF0EA638
Diagnosis. Body elongate, cylindrical, incompletely segmented. Urosome four-
segmented; caudal ramus with six setae. Female antennule 20-segmented, with large
aesthetasc on antepenultimate segment; first segment with one seta. Male antennule
18-segmented, geniculate between 15th and 16th segments and between 16th and 17th
segments. Antenna consisting of coxa, basis, one-segmented small exopod, and three-
segmented endopod; third endopodal segment terminating in large spine. Oral siphon
extending over insertions of maxillipeds. Mandible consisting of thin stylet and indistinctly
two-segmented palp tipped with two subequal setae. Maxillule bilobed; inner lobe about 3
times longer than outer lobe, tipped with four large setae; outer lobe tipped with three setae.
Maxilla two-segmented, distal segment claw-like. Maxilliped consisting of syncoxa, basis,
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 3/26
and four-segmented endopod. Leg 1 with three-segmented rami. Leg 2 with two-segmented
rami. Leg 3 with obscurely segmented protopod, two-segmented exopod, lacking endopod.
Leg 4 as vestigial lobe bearing two setae. Armature formula for legs 1–3 as follows: leg 5
represented by one seta on fifth pedigerous somite and one-segmented exopod bearing
three setae.
Coxa Basis Exopod Endopod
Leg 1 0-0 1-1 I-0; I-0; II, 2, 2 0-1; 0-1; 1, 2, 3
Leg 2 0-0 1-0 I-0; I, II, 3 0-1; 1, 2, 2
Leg 3 0-0 0-0 I-0; 0, II, 0 Absent
Type species. Amalomyzon elongatum n. gen. n. sp. (original designation).
Etymology. The name of the new genus, Amalomyzon, as a new genus is a combination
of Greek amal (=soft) and myz (=to suck), referring to the soft body of the type species.
Gender neuter.
Remarks.Lee & Kim (2017) have listed 12 genera in the family Asterocheridae in which
leg 4 is uniramous or represented by a lobe or a seta as in Amalomyzon n. gen. These genera
comprise three genera (Coralliomyzon Humes and Stock, 1991, Cholomyzon Stock and
Humes, 1969, and Temanus Humes, 1997). They were originally included in the family
Coralliomyzontidae Humes and Stock, 1991. Most of these genera have a biramous leg
3. Only two genera, Andapontius Lee & Kim, 2017 and Holobinus Lee & Kim, 2017, have a
uniramous leg 3 like Amalomyzon n. gen.
Amalomyzon n. gen. differs from genera Andapontius and Holobinus in having a 20-
segmented female antennule with an aesthetasc on the antepenultimate segment (vs.
18-segmented female antennule with an aesthetasc on the terminal segment in both
Andapontius and Holobinus). The new genus is further distinguished from Andapontius
in having two-segmented endopod of leg 2 (vs. three-segmented in Andapontius) and
two-segmented exopod of leg 3 (vs. 1-segmented in Andapontius). It can be distinguished
from Holobinus in having a two-segmented exopod of leg 2 (vs. three-segmented exopod
of leg 2 in Holobinus) and two spines plus four setae on the third exopodal segment of leg
4 (vs. two spines plus two setae in Holobinus). It should be noted that exopods of legs 3
and 4 of Andapontius are one-segmented. However, Lee & Kim (2017) have erroneously
written two-segmented exopods of legs 3 and 4 of Andapontius. These and other differences
between the new genus and its two related genera are summarized in Table 2.
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 4/26
Table 2 Differentiation of three asterocherid genera.
Genus
Characters Andapontius
Lee & Kim, 2017
Holobinus
Lee & Kim, 2017
Amalomyzon
n. gen.
Body form Broad Narrow Cylindridal
Female antennule 18-segmented 18-segmented 20-segmented
Armature of 3rd exopodal segment of leg 1 2 spines +4 setae 2 spines +2 setae 2 spines +4 setae
Leg 2 exopod 3-segmented 3-segmented 2-segmented
Leg 2 endopod 3-segmented 2-segmented 2-segmented
Leg 3 exopod 1-segmented 2-segmented 2-segmented
Leg 4 1-segmented As a lobe As a lobe
Amalomyzon elongatum n. sp.
urn:lsid:zoobank.org:act:3CAFD973-9823-4672-8F19-14665C4D5CFD
Figs. 2,3and 4
Type material. Holotype (intact ♀; NIBR NIBRIV0000901203), intact paratypes (9 ♀
♀, 2 ♂ ♂; NIBR NIBRIV0000901204), and dissected paratypes (1 ♀, 1 ♂) from washings
of the sponge Dysidea dokdoensis Kang, Lee & Sim, 2020, SCUBA diving, at ‘‘Elephant
Rock’’, Ulleung Island, Korean East Sea (37◦3202500N, 130◦5005100 E), a depth of 35 m, 29
Aug. 2018, coll. Jong Kuk Kim. Intact type specimens have been deposited in the National
Institute of Biological Resources (NIBR), Incheon, Korea. Dissected paratypes are kept in
the collection of I-H Kim.
Description
Female. Body (Figs. 2A and 2B) elongated, nearly cylindrical, indistinctly segmented.
Body lengths of figured specimens 842 µm. Prosome 545 µm long, more than twice as
long as wide, consisting of cephalosome and 4 indistinctly defined metasomal somites.
Cephalosome circular, 227 ×264 µm, wider than metasomal somites. Metasome gradually
narrowing posteriorly; metasomal somites defined by lateral constrictions between them.
Urosome (Fig. 2C) 4-segmented, clearly defined from prosome. Fifth pedigerous somite
132 µm wide. Genital double-somite slightly wider than long (120 ×129 µm), widest at
30% region of double-somite length, narrowing posteriorly; genital apertures positioned
dorsolaterally at 38% region of double-somite length just posterior to widest region.
Abdomen incompletely articulated from genital double-somite. Two free abdominal
somites (50 ×70 µm and 45 ×58 µm, respectively), both somites unornamented. Caudal
ramus (Fig. 2D) 1.53 times longer than wide (29 ×19 µm), armed with 3 distal and 3
subdistal naked setae; 3 subdistal setae positioned at subequal planes; all setae longer than
ramus.
Rostrum (Fig. 2E) small, spatulate, with convex distal margin. Antennule (Fig. 2F) 153
µm long, 20-segmented, gradually narrowing distally; armature formula 1, 2, 2, 2, 2/2, 2,
2, 5, 2/2, 2, 2, 2, 2/2, 2, 1+aesthetasc, 3, and 9; all setae naked, slender. Antenna (Fig. 2G)
consisting of coxa, basis, exopod, and endopod; coxa short and unarmed; basis broadening
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 5/26
Figure 2 Amalomyzon elongatum n. gen. n. sp., female. (A) Habitus, dorsal. (B) Habitus, right. (C)
Urosome, dorsal. (D) Right caudal ramus, dorsal. (E) Cephalic region, ventral. (F) Antennule. (G) An-
tenna. (H) Mandible. Scale bar: 0.1 mm in A and B, 0.05 mm in C and E, and 0.02 mm in D and F–H.
Full-size DOI: 10.7717/peerj.14889/fig-2
distally, unarmed; exopod small, unsegmented, twice longer than wide (8 ×4µm), armed
with two distal and one middle setae; endopod three-segmented; first endopodal segment
31 µm long, unarmed but ornamented with spinules along outer margin; second endopodal
segment small, with 1 seta; third endopodal segment 12 µm long, with two small setae
subdistally, terminating in nearly straight spine (32 µm long).
Oral siphon (Fig. 2E) 193 ×43 µm, extending beyond insertions of maxilliped, not
reaching insertions of legs 1. Mandible (Fig. 2H) consisting of stylet and palp; stylet 173 µm
long, thin, its distal teeth hardly visible under microscope; palp 25 ×8µm, much shorter
than stylet, indistinctly two-segmented at distal quarter, tipped with two naked (setae
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 6/26
Figure 3 Amalomyzon elongatum n. gen. n. sp., female. (A) Maxillule. (B) Maxilla. (C) Maxilliped. (D)
Leg 1. (E) Leg 2. (F) Leg 3. (G) Leg 4 pair. (H) Leg 5. (I) Left genital aperture. Scale bar: 0.02 mm.
Full-size DOI: 10.7717/peerj.14889/fig-3
68 µm and 58 µm long, respectively). Maxillule (Fig. 3A) bilobed; inner lobe (precoxal
endite) 64 ×20 µm, tapering distally, tipped with 4 long setae (longest seta: 120 µm),
and ornamented with one row of spinules and one row of setules; outer lobe (palp), 20
×5µm, about one-third as long as inner lobe, with two distal setae (longer seta: 50 µm)
and one subdistal seta. Maxilla (Fig. 3B) two-segmented; proximal segment unarmed;
distal segment claw-like distal part, ornamented with one transverse row of fine setules at
two-fifths region of segment length. Maxilliped (Fig. 3C) consisting of syncoxa, basis, and
four-segmented endopod; syncoxa with one small seta at inner distal corner; basis being
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 7/26
Figure 4 Amalomyzon elongatum n. gen. n. sp., male. (A) Habitus, dorsal. (B) Urosome, ventral. (C)
Antennule. (D) Leg 5 pair. Scale bar: 0.1 mm in A, 0.05 mm in B, and 0.02 mm in C and D.
Full-size DOI: 10.7717/peerj.14889/fig-4
longest segment, unarmed, with parallel outer and inner margins; endopodal segments
armed with zero, one, one, and one seta, respectively; terminal claw nearly straight, 25 µm
long, 1.4 times longer than third endopodal segment.
Leg 1 (Fig. 3D) biramous, with three-segmented rami. Leg 2 (Fig. 3E) with 2-segmented
rami. Leg 3 (Fig. 3F) with two-segmented exopod; endopod absent. Leg 4 (Fig. 3G) as
small lobe bearing 1 short, spiniform apical seta and one longer, naked lateral seta. Inner
coxal seta absent in legs 1–3. Inner distal corner of leg 1 produced. Outer spine on first
exopodal segment large, 25 µm long, extending over midway of third exopodal segment.
Articulation between second and third endopodal segments indistinct. Protopod of leg 3
indistinctly segmented. Exopodal segment of leg 4 about twice longer than wide (17 ×8
µm), armed with 3 naked setae distally. Armature formula for legs 1–3 as follows:
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 8/26
Coxa Basis Exopod Endopod
Leg 1 0-0 1-1 I-0; I-0; II, 2, 2 0-1; 0-1; 1, 2, 3
Leg 2 0-0 1-0 I-0; I, II, 3 0-1; 1, 2, 2
Leg 3 0-0 0-0 I-0; 0, II, 0 Lacking
Leg 5 (Fig. 3H) consisting of one lateral naked seta on fifth pedigerous somite and
one-segmented exopod; exopodal segment 17 ×8µm, with nearly parallel inner and outer
margins, armed with three naked setae. Leg 6 (Fig. 3I) represented by one seta and one
denticle on genital operculum.
Male. Body (Fig. 4A) as in female. Body length of figured specimen 580 µm long.
Urosome (Fig. 4B) 5-segmented. Genital somite wider than long (80 ×110 µm), with
convex lateral margins. Abdomen gradually narrowing posteriorly. Three free abdominal
somites (48 ×66 µm, 36 ×59 µm, and 30 ×45 µm, respectively). Caudal ramus 1.67
times longer than wide (25 ×15µm). Rostrum as in female.
Antennule (Fig. 4C) 18-segmented, with geniculation between antepenultimate and
penultimate segments; armature formula 1, 2, 2, 2, 2/2, 2, 1, 5, 2/1, 2, ?, ?, ?/?, 2+aesthetasc,
and 8+aesthetasc (setations of thirteenth to sixteenth segments obscure due to overlaps of
setae and segments). Antenna and mouthparts as in female.
Legs 1–3 as in female. Leg 4 (Fig. 4D) incompletely two-segmented; proximal segment
with one seta laterally; distal segment unarmed or armed with one apical seta. Leg 5 (Fig.
3B) similar to that of female. Leg 6 (Fig. 4B) represented by two equal, small setae on distal
apex of genital operculum.
Etymology. The specific name refers to the elongate body of the new species.
Remarks. The body form of Amalomyzon elongatum n. sp. is similar to that of
Tuphacheres micropus Stock, 1965 known in the Mediterranean Sea (Stock, 1965). However,
these two species differ from each other at the generic level as they exhibit different ways
of leg segmentation reductions.
Dokdocheres n. gen.
urn:lsid:zoobank.org:act:6787FECB-E7FA-48DB-97CF-73EBDEB4E151
Diagnosis. Body broad, dorsoventrally flattened. Prosome consisting of cephalothorax
and three metasomal somites. Urosome four-segmented, with two-segmented abdomen.
Caudal ramus with six setae. Antennule 18-segmented, with aesthetasc on antepenultimate
segment; first segment with one seta. Antenna consisting of coxa, basis, one-segmented
exopod, and 2-segmented endopod; exopodal segment elongate, more than half length
of first endopodal segment, with three setae; second endopodal segment terminating in
slender claw. Oral cone short, stout. Mandible consisting of stylet bearing six teeth distally
and palp tipped with one seta. Maxillule bilobed; inner lobe tipped with three large setae;
outer lobe with three large and one small setae. Maxilla 2-segmented; distal segment as claw.
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 9/26
Maxilliped consisting of syncoxa, basis, and 3-segmented endopod. Legs 1–4 biramous,
with 3-segmented rami. Armature formula for legs 1–4 as follows:
Coxa Basis Exopod Endopod
Leg 1 0-1 1-0 I-1; I-1; I+1, 2, 2 0-1; 0-2; 1, 1+I, 3
Leg 2 0-1 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 1, II, I+2
Leg 3 0-1 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 1, I, I+2
Leg 4 0-0 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 0, I, 2
Leg 5 consisting of protopod bearing one seta and one-segmented exopod bearing 3
setae.
Type species. Dokdocheres rotundus n. gen. n. sp. (original designation).
Etymology. The name of the new genus is derived from Dokdo Island, the type locality
of the type species, and -cheres, the ending of Asterocheres, the type genus of the family
Asterocheridae. Gender masculine.
Remarks. The establishment of Dokdocheres n. gen. is justifiable by multiple
extraordinary features in the leg setation of its type species, D. rotundus n. gen. n.
sp., as follows: (1) the third exopodal segment of leg 1 is armed with 1 spine plus five
setae (armature formula I+1, 2, 2), which is a unique armature condition in the family
Asterocheridae; (2) the armature formula of the third endopodal segment of leg 1 is 1,
1+I, 3 (having 1 distal spine), which is a feature shared by three genera (Gomumucheres
Humes, 1996, Parasterocheres Humes, 1996, and Phyllocheres Humes, 1996) within the
family, all of which are associated with the sponge Dysidea in the Moluccas (Humes, 1996);
(3) the armature formula of the third exopodal segment of legs 2–4 is II, I, 4. The same
armature formula of the third exopodal segment is exhibited on leg 2 in 15 genera, leg 3
in 10 genera, and leg 4 in four genera. However, only Dokdocheres n. gen. and two existing
genera (Siphonopontius Malt, 1991 and Stenomyzon Kim, 2010) exhibit the same armature
condition in all legs 2–4; (4) the armature formula of the third endopodal segment of leg
4 is 0, I, 2. This armature condition is shared by five existing genera (Asterocheroides Malt,
1991, Cecidomyzon Stock, 1981, Cephalocheres Kim, 2010, Hammatimyzon Stock, 1981,
and Scottomyzon Giesbrecht, 1897). Therefore, Dokdocheres n. gen. can be recognized by
the above first feature alone or by the combination of the other three unusual features.
Dokdocheres rotundus n. sp.
urn:lsid:zoobank.org:act:AB9D5F75-F663-4593-9058-5C5CA9F9B02A
Figs. 5,6and 7
Type material. Holotype (intact ♀; NIBR NIBRIV0000901205) and paratype (♀,
dissected and mounted on a slide) from washings of the sponge Acanthella vulgata Thiele,
1898, SCUBA diving, Dokdo Island, Korean East Sea (37◦1404400N, 131◦5105400 E), a depth
of 22 m, 23 Apr. 2015, coll. Hyun Soo Rho. Holotype has been deposited in the National
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 10/26
Institute of Biological Resources (NIBR), Incheon, Korea. Dissected paratype is kept in the
collection of I.-H. Kim.
Description
Female. Body (Fig. 5A) broad, dorsoventrally flattened. Body length of dissected and
figured paratype, 0.62 mm. Prosome subcircular, 518 ×443 µm, only slightly longer than
wide. Cephalothorax 280 µm long. Third and fourth pedigerous somites with concave
posterodorsal margin. All prosomal somites with round posterolateral corners. Urosome
(Fig. 5B) small, four-segmented, occupying 16% of body length. Fifth pedigerous somite 62
µm wide, broadening posteriorly. Genital double-somite laterally expanded, rhomboidal,
wider than long (58 ×89 µm), widest at 58% of double-somite length; genital apertures
large, located dorsolaterally posterior to widest region. Abdomen two-segmented. First
abdominal somite very short, 5 ×45 µm. Anal somite (second abdominal somite) 13 ×
44 µm. Caudal ramus (Fig. 5C) 1.07 times longer than wide (16 ×15 µm), armed with 6
setae, ornamented with fine spinules on ventrodistal margin; setae III–VI pinnate, setae II
and VII naked.
Rostrum (Fig. 5D) longer than wide (90 ×74µm), widest at proximal quarter, tapering
distally, with truncate distal apex. Antennule (Fig. 5E) gradually narrowing distally,
18-segmented; first segment longest, third segment second longest; armature formula 1, 2,
6, 2, 2/2, 6, 2, 2, 2/ 2, 2, 2, 2, 2/2+aesthetasc, 2, and 11; setae naked, relatively long, highly
flexible. Antenna (Fig. 5F) consisting of coxa, basis, 1-segmented exopod, and 2-segmented
endopod; coxa short, unarmed; basis with thin spinules on inner margin; exopod 4.50
times longer than wide (36 ×8µm), gradually broadening distally, about 68% as long
as first endopodal segment, armed distally with 3 setae, 2 of them longer than exopodal
segment; first endopodal segment 53 ×25 µm, unarmed, with setules on distal part of
outer margin; second endopodal segment small, 16 ×9µm, armed with 2 long subdistal
setae, 2 min distal setae, terminating in slender claw of 53 µm long.
Oral cone (Fig. 5G) short, stout, with tuft of setules at distal apex of labrum and labium.
Mandible consisting of stylet (Fig. 5H) and palp (Fig. 5I); stylet curved along distal third,
with 6 teeth distally; palp small, unsegmented, 17 ×5µm, tipped with 1 long seta; no
articulation present between palp and distal seta. Maxillule (Fig. 6A) bilobed; inner lobe
(precoxal endite) about 36 ×14 µm, tipped with three large, pinnate setae and ornamented
with several spinules subdistally; outer lobe (palp) 41 ×10 µm, slightly longer than inner
lobe, tipped with three large and one small setae. Maxilla (Fig. 6B) 2-segmented; proximal
segment (syncoxa) broad, unarmed; distal segment (basis) as slender, strongly curved claw,
unarmed, with rows of minute spinules at distal region. Maxilliped (Fig. 6C) 5-segmented,
consisting of syncoxa, basis, and 3-segmented endopod; syncoxa unarmed; basis 88 µm
long, with one long seta (41 µm long) at 48% region of inner margin; first to third
endopodal segments with two, one and one setae, respectively; terminal segment 38 µm
long, distal seta large, longer than segment; terminal claw 58 µm long, with 2 min spinules
near tip.
Legs 1–4 (Figs. 6E,7A and 7B) biramous, with 3-segmented rami. Inner coxal seta
present in legs 1–3, absent in leg 4. Basis of leg 1 lacking inner distal element. Outer seta
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 11/26
Figure 5 Dokdocheres rotundus n. gen. n. sp., female. (A) Habitus, dorsal. (B) Urosome, dorsal. (C)
Right side of abdomen, ventral. (D) Rostrum. (E) Antennule. (F) Antenna. (G) Oral cone, right. (H)
Mandibular stylet. (I) Mandibular palp. Scale bar: 0.1 mm in A, 0.02 mm in B, E, F, H, and I, 0.01 mm in
C, and 0.05 mm in D and G.
Full-size DOI: 10.7717/peerj.14889/fig-5
on basis of legs 1–4 large, naked. Second endopodal segment of legs 1–3 expanded. Spines
on legs 1–4 well-developed, naked without serration. Distal processes on exopodal and
endopodal segments well-developed, acutely pointed. Second endopodal segments with
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 12/26
Figure 6 Dokdocheres rotundus n. gen. n. sp., female. (A) Maxillule. (B) Maxilla. (C) Maxilliped. (D)
Leg 1. (E) Leg 2. Scale bar: 0.02 mm.
Full-size DOI: 10.7717/peerj.14889/fig-6
monocuspid outer distal process. Third exopodal segment of leg 1 with characteristic
armature, with one spine plus five setae. Armature formula for legs 1–4 as follows:
Leg 5 (Figs. 5B and 7C) two-segmented, consisting of protopod and one-segmented
exopod; protopod, wider than long, not articulated from somite, with one long, naked seta
(59 µm long) dorsodistally; exopodal segment 28 ×12 µm, with three weakly pinnate setae
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 13/26
Figure 7 Dokdocheres rotundus n. gen. n. sp., female. (A) Endopod of leg 3. (B) Leg 4. (C) Leg 5. Scale
bar: 0.02 mm.
Full-size DOI: 10.7717/peerj.14889/fig-7
Coxa Basis Exopod Endopod
Leg 1 0-1 1-0 I-1; I-1; I+1, 2, 2 0-1; 0-2; 1, 1+I, 3
Leg 2 0-1 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 1, II, I+2
Leg 3 0-1 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 1, I, I+2
Leg 4 0-0 1-0 I-1; I-1; II, I, 4 0-1; 0-2; 0, I, 2
(45, 50, and 20 µm long, respectively, from dorsal to ventral). Leg 6 (Fig. 5B) represented
by 1 seta and one spinule on genital operculum.
Male. Unknown.
Etymology. The name of the new species is derived from the Latin rotund (=round),
alluding to the subcircular body form.
Genus Asterocheres Boeck, 1859
Asterocheres banderaae n. sp.
urn:lsid:zoobank.org:act:670BF905-E285-453E-96C0-56980A041CE7
Figs. 8,9and 10
Type material. Holotype (intact ♀; NIBR NIBRIV0000901206), intact paratypes (25 ♀♀,
2♂♂; NIBR NIBRIV0000901207), and dissected paratypes (2 ♀ ♀, 1 ♂) from washings
of the sponge Petrosia corticata (Wilson, 1925), trimix SCUBA diving, a depth of 45.2 m,
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 14/26
Dokdo Island, Korean East Sea, 06 Jul. 2022, coll. Taekjun Lee. Intact type specimens have
been deposited in the National Institute of Biological Resources (NIBR), Incheon, Korea.
Dissected paratypes are kept in the collection of I.-H. Kim.
Description
Female. Body (Fig. 8A) rather narrow. Body length 803 µm in dissected and figured
specimen (756–810 µm in 10 measured specimens). Prosome 553 µm long, tapering
posteriorly. Cephalothorax subcircular, wider than long (342 ×409µm). Second, third, and
fourth pedigerous somites 309, 262, and 178 µm wide, respectively. All prosomal somites
with rounded lateral corners. Urosome (Fig. 8B) 4-segmented. Fifth pedigerous somite
90 µm wide. Genital double-somite slightly wider than long (108 ×112µm), consisting
expanded anterior half and tapering distal half; genital apertures large, positioned dorsally;
lateral margin of posterior half (Fig. 8C) with row of about 10 (9–11) thin setules; dorsal
and ventral surfaces lacking scales. Two free abdominal somites 45 ×53, and 38 ×48
µm, respectively. Caudal ramus slightly wider than long (21 ×22 µm), with 6 setae; 2
large mid-terminal setae (setae IV and V) stiff, almost not flexible; seta IV usually curved
proximally and directed posterolaterally.
Rostrum absent. Antennule (Fig. 8D) 316 µm long, 20-segmented; armature formula 7
on ninth segment, 2+aesthetasc on antepenultimate segment, 11 on terminal segment, two
on other segments. Antenna (Fig. 8E) consisting of coxa, basis, one-segmented exopod,
and three-segmented endopod; basis 130 ×24 µm, ornamented with longitudinal row
of minute spinules; Exopod small, 2.73 times longer than wide (12 ×4.4 µm), with two
unequal distal and one middle setae; first endopodal segment 3.06 times longer than wide
(55 ×18 µm) with fine setules along outer margin; second endopodal segment small with
1 stiff seta; third endopodal segment with 3 setae, terminating in spine of 42 µm long.
Oral cone (Fig. 8F) 150 ×68 µm, extending to insertions of maxilliped, with about
15 min denticles on distal regions of lateral margins. Mandible (Fig. 8G) consisting of
slender stylet and palp; stylet 146 µm long; palp slender, 9.0 times longer than wide (45
×5µm), tipped with two setae, longer one 102 µm long, and shorter one 38 µm long;
palp plus longer seta as long as stylet. Maxillule (Fig. 8H) bilobed; inner lobe 3.24 times
longer than wide (55 ×17 µm), about three times longer than outer lobe, tipped with 5
setae (one of them minute), ornamented with long setules on inner surface, longest seta 76
µm long; outer lobe 2.25 times longer than wide (18 ×8µm) tipped with three long and
one short setae. Maxilla (Fig. 8I) stout, two-segmented; both segments unarmed; proximal
segment proximally with flexible tube of maxillary gland; distal segment claw-like, as long
as proximal segment, with row of fine spinules subdistally. Maxilliped (Fig. 8J) consisting
of syncoxa, basis, and 4-segmented endopod; syncoxa with 1 seta subdistally on inner
margin and row of minute spinules at outer distal corner; basis with 1 small, vestigial seta
near middle of inner margin and minute spinules on outer margin; 4 endopodal segment
with 2, 0, 1, and 1 seta, respectively; fourth endopodal segment 35 µm long, terminating
in slightly curved claw of 58 µm long.
Legs 1–4 (Figs. 9A–9E) biramous, with 3-segmented rami. Inner coxal seta absent in
legs 1 and 4, present in legs 2 and 3. Inner distal seta (Fig. 8B) on basis of leg 1 proximally
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 15/26
Figure 8 Asterocheres banderaae n. sp., female. (A) Habitus, dorsal. (B) Urosome, dorsal. (C) Left side
of genital double-somite. (D) Antennule. (E) Antenna. (F) Oral cone. (G) Mandible. (H) Maxillule. (I)
Maxilla. (J) Maxilliped. Scale bar: 0.1 mm in A, 0.05 mm in B and F, 0.02 mm in C–E and G–J.
Full-size DOI: 10.7717/peerj.14889/fig-8
inflated, 46 µm long, with perpendicular setules (or spinules) on proximal part of outer
margin. Armature formula for legs 1–4 as follows:
Leg 5 (Fig. 9F) consisting of protopod bearing one dorsodistal seta and one-segmented
exopod. Exopodal segment 1.82 times longer than wide (31 ×17 µm), armed with 3 setae
and ornamented with spinules on dorsal surface; subdistal ventral seta naked, thin, 25 µm
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 16/26
Figure 9 Asterocheres banderaae n. sp., female. (A) Leg 1. (B) Inner distal seta on basis of leg 1. (C) Leg
2. (D) Leg 3. (E) Leg 4. (F) Leg 5. Scale bar: 0.02 mm.
Full-size DOI: 10.7717/peerj.14889/fig-9
Coxa Basis Exopod Endopod
Leg 1 0-0 1-1 I-1; I-1; III, 2, 2 0-1; 0-2; 1, 2, 3
Leg 2 0-1 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 2, 3
Leg 3 0-1 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 1+I, 3
Leg 4 0-0 1-0 I-1; I-1; III, I, 4 0-1; 0-2; 1, 1+I, 2
long; distal and subdistal dorsal setae 42 and 36 µm long, respectively, ornamented with
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 17/26
Figure 10 Asterocheres banderaae n. sp., male. (A) Habitus, dorsal. (B) Urosome, dorsal. (C) Anten-
nule. (D) Maxilliped. (E) Endopod of leg 3. Scale bar: 0.1 mm in A, 0.05 mm in B, and 0.02 mm in C–E.
Full-size DOI: 10.7717/peerj.14889/fig-10
stiff setules (or setule-like spinules). Leg 6 (Fig. 8B) represented by one small spinule and
one naked seta on genital operculum.
Male. Body (Fig. 10A) similar in form to that of female. Body length 580 µm in dissected
and figured specimen. Prosome 393 µm long. Cephalothorax 227 ×270 µm. Urosome
(Fig. 10B) five-segmented. Fifth pedigerous somite 75 µm wide. Genital somite much
wider than long (98 ×134 µm), with round lateral margins and concave posterodorsal
margin, ornamented with triangular scales scattered on dorsal and lateral surfaces. Three
abdominal somites 20 ×49, 18 ×49, and 27 ×47 µm, respectively. Caudal ramus 18 ×
21 µm; seta IV directed posteriorly, unlike that of female.
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 18/26
Antennule (Fig. 10C) 17-segmented, geniculate between fifteenth and sixteenth
segments; armature formula 2, 2, 2, 2, 2/2, 2, 2, 7, 2/2, 4, 2, 2, 2/1+aesthetasc, and 9;
one distal seta on terminal segment spiniform, modified. Antenna as in female.
Oral cone, mandible, maxillule, and maxilla as in female. Maxilliped (Fig. 10D)
segmented as in female, but inner subdistal element on syncoxa transformed to spine
tipped on protrusion of syncoxa; second endopodal segment bearing one small seta.
Legs 1, 2, and 4 as in female. Leg 3 endopod (Fig. 10E) sexually dimorphic: second
segment with 2 massive, spinulose spines (instead of setae in female); distal spine on third
segment longer than that of female. Leg 5 as in female. Leg 6 (Fig. 10B) represented by two
unequal setae on genital operculum.
Etymology. The new species is named in honor of Dr. Bandera for her contribution to
the taxonomy of the genus Asterocheres.
Remarks. The genus Asterocheres is inconveniently large, comprising about 90 known
species (WoRMS Editorial Board, 2022), many of which are incompletely described.
Nevertheless, A. banderaae n. sp. is distinguishable from its congeners by its several
characteristic morphological features. The coxa of leg 1 of the new species lacks an inner
seta. According to Bandera & Conradi (2016), this feature is also present in three existing
species of Asterocheres (A. eugenioi Bandera & Conradi, 2014, A. sarsi Bandera and Conradi,
2009, and A. trisetatus Kim, 2010). In A. eugenioi and A. sarsi, caudal rami are 1.5 or more
times longer than wide with the oral cone extending to the insertion of leg 1 (Bandera &
Conradi, 2014). In A. trisetatus, the third endopodal segment of leg 1 is elongated (Kim,
2010). These features of the three species are not applicable to A. banderaae n. sp.
The second endopodal segment of leg 3 is sexually dimorphic, armed with two pinnate
setae in the female, but with two strong specialized spines in males. Sexual dimorphism
in leg 3 has been reported in several species of Asterocheres, such as A. bahamensis Kim,
2010, A. nidorelliae Reyes-González & Suárez-Morales, 2021, A. peniculatus Kim, 2010,
A. plumosus Kim, 2010, A. urabensis Kim, 2004, and A. walteri Kim, 2004 (Kim, 2004;
Kim, 2010;Reyes-González & Suárez-Morales, 2021). However, in all these species, sexual
dimorphism in leg 3 occurs on the third endopodal segment. None of them occurs on the
second endopodal segment as in A. banderaae n. sp. They also differ from the new species
in various other morphological aspects.
The syncoxa (first segment) of the male maxilliped of the new species bears a specialized
inner distal spine. This feature is shared only with A. cuspis Kim, 2016 known in the
eastern coast of Korea. Interestingly, like A. banderaae n. sp., A. cuspis has a posteriorly
tapering body and a proximally swollen inner distal seta on the basis of leg 1. Despite these
similarities, A. cuspis is distinguished from the new species by having a two-segmented
mandibular palp (cf. 1-segmented in A. banderae n. sp.) and an inner coxal seta on leg 1
without sexual dimorphism on the second endopodal segment of leg 3.
Many species of Asterocheres were described based only on their females. Thus, the
above characters (2) and (3) cannot be used for differentiating these species. However, A.
banderaae n. sp. is readily recognizable by the above feature (1) and additional diagnostic
features of females such as 1-segmented mandibular palp, similar lengths of the mandibular
palp and its stylet, proximally swollen inner distal seta on the basis of leg 1, presence of
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 19/26
Figure 11 Scottocheres nesobius n. sp., female. (A) Habitus, dorsal. (B) Urosome, dorsal. (C) Right cau-
dal ramus, dorsal. (D) Antennule. (E) Antenna. (F) Proximal part of oral siphon. (G) Mandible. (H) Max-
illule. (I) Maxilla. (J) Maxilliped. (K) Leg 1. (L) Leg 5. Scale bar: 0.1 mm in A, 0.05 mm in B, and 0.02 mm
in C–L.
Full-size DOI: 10.7717/peerj.14889/fig-11
about 10 setules on the lateral margin of the genital double-somite, and absence of an inner
coxal seta on leg 4.
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 20/26
Figure 12 Scottocheres nesobius n. sp., female. (A) Leg 2. (B) Leg 3. (C) Leg 4. (D) Left genital aperture.
Male: (E) Habitus, dorsal. (F) Urosome, ventral. (G) Antennule. (H) Maxilliped. Scale bar: 0.02 mm in A-
D, G, and H, 0.1 mm in E, and 0.05 mm in F.
Full-size DOI: 10.7717/peerj.14889/fig-12
Genus Scottocheres Giesbrecht, 1897
Scottocheres nesobius n. sp.
urn:lsid:zoobank.org:act:4ACBCDB8-4CA4-4803-ABA6-DAC84F4E7661
Figs. 11 and 12
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 21/26
Type material. Holotype (intact ♀; NIBR NIBRIV0000901208), intact paratypes (7
♀ ♀; NIBR NIBRIV0000901209), and dissected paratypes (2 ♀ ♀, 1 ♂) from washings of
the sponge Myxilla producta Hoshino, 1981, trimix SCUBA diving, a depth of 45.2 m,
Dokdo Island, Korean East Sea, 06 Jul. 2022, coll. Taekjun Lee. Intact type specimens have
been deposited in the National Institute of Biological Resources (NIBR), Incheon, Korea.
Dissected paratypes are kept in the collection of I.-H. Kim.
Description
Female. Body (Fig. 11A) narrow. Body length 690 µm in dissected and figured specimen.
Mean body length 702 µm (655–740 µm) based on seven specimens. Prosome 368 µm
long. Cephalothorax 207 ×223 µm. Three metasomal somites (second, third, and fourth
pedigerous somites) 189, 164, and 127 µm wide, respectively. Posterolateral corners of all
prosomal somites rounded. Urosome (Fig. 11B) 4-segmented. Fifth pedigerous somite 95
µm wide. Genital double-somite 1.33 times longer than wide (118 ×89µm), with tooth-like
process on lateral margin at anterior third; genital apertures positioned dorsally at anterior
quarter. Two free abdominal somites 47 ×45 and 34 ×38 µm, respectively. Anal somite
with two pairs of minute spinules on posteroventral margin near posteromedian incision
(Fig. 11C). Caudal ramus (Fig. 11C) 6.07 times longer than wide (91 ×15 µm), widened
at distal region, armed with 6 setae positioned distally and subdistally; setae IV-VI pinnate,
other setae naked.
Rostrum absent. Antennule (Fig. 11D) 172 µm long, 17-segmented; armature formula
1, 2, 3, 1, 2/1, 2, 4, 2, 2/1, 2, 1, 1, 0/1+aesthetasc, and 12; setae small and naked; third
segment with rudiment of partial articulation. Antenna (Fig. 11E) consisting of coxa,
basis, one-segmented exopod, and two-segmented endopod; coxa short, unarmed; basis
50 µm long; exopod 8 ×4.5 µm, positioned distal quarter of endopod, armed with 3 thin
setae (two unequal distal and one in middle); proximal endopodal segment 38 µm long,
unarmed but ornamented with patch of minute spinules at inner subdistal region; distal
endopodal segment with 4 small setae and terminating in slender, arched spine of 57 µm
long.
Oral siphon (Fig. 11F) slender, extending to insertions of leg 4. Mandible (Fig. 11G)
represented by thread-like stylet; palp absent. Maxillule (Fig. 11H) bilobed; inner lobe
tapering distally, 28 ×13 µm, tipped with 2 long and 1 short setae (longest one 76 µm
long) and ornamented with spinules on inner margin and distal region; outer lobe small,
13 ×2.5 µm, tipped with 2 unequal setae. Maxilla (Fig. 11I) slender, two-segmented; distal
segment articulated at 60% region of segment length, with claw-like distal part. Maxilliped
(Fig. 11J) slender, consisting of syncoxa, basis, and three-segmented endopod; syncoxa with
one small seta at inner distal corner; basis 60 µm long, unarmed; first to third endopodal
segments with two, one and one seta, respectively; third endopodal segment 27 µm long,
terminating in long spine of 65 µm long.
Legs 1–4 (Figs. 11K,12A–12C) biramous, with 3-segmented rami. Inner coxal seta
absent in legs 1 and 2, but present in legs 3 and 4. Outer seta on basis small, naked. Inner
distal spine on basis of first leg 21 µm long. Second endopodal segment of legs 1–3 with 1
inner seta, that of leg 4 with 2 inner setae. Armature formula for legs 1–4 as follows:
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 22/26
Coxa Basis Exopod Endopod
Leg 1 0-0 1-I I-1; I-1; II, 2, 2 0-1; 0-1; 1, 2, 3
Leg 2 0-0 1-0 I-1; I-1; II, I, 4 0-1; 0-1; 1, 2, 3
Leg 3 0-1 1-0 I-1; I-1; II, I, 4 0-1; 0-1; 1, I, 3
Leg 4 0-1 1-0 I-1; I-1; II, I, 3 0-1; 0-2; 1, I, 2
Leg 5 (Fig. 11L) 2-segmented; proximal segment (protopod) clearly articulated from
somite, nearly triangular, 47 ×43 µm, with 2 setae (medial and lateral); distal segment
(exopod) elliptical, 1. 75 times longer than wide (51 ×29 µm), with 3 small setae distally.
Leg 6 (Fig. 12D) represented by 2 small setae and 1 spiniform process on genital operculum.
Male. Body (Fig. 12E) narrow. Body length of dissected and figured specimen 573 µm.
Cephalothorax 180 ×182 µm. Urosome (Fig. 12F) 5-segmented. Genital somite 79 ×
99 µm, nearly quadrangular, with notch on both sides of posterodorsal margin. Three
abdominal somites 46 ×58, 36 ×45, and 27 ×37 µm, respectively, Caudal ramus 3.81
times longer than wide (61 ×16 µm).
Rostrum absent. Antennule (Fig. 12G) 182 µm long, 15-segmented, geniculate between
antepenultimate and penultimate segments; armature formula 1, 2, 5, 2, 3/2, 2, 6, 3, 3/2, 3,
1, 3+aesthetasc, and 11; proximal seta on 12th segment minute, spinule-like. Antenna as
in female.
Oral siphon, mandible, maxillule, and maxilla as in female. Maxilliped (Fig. 12H)
slightly different from that of female in having angular protrusion at proximal quarter of
inner margin of basis. Legs 1–5 as in female. Leg 6 represented by 3 small setae on genital
operculum (Fig. 12F).
Etymology. The specific name nesobius is derived from Greeks neso (=island) and bio
(=life), alluding to the discovery of the species in the island.
Remarks. The third exopodal segment of legs 2–4 of Scottocheres nesobius n. sp. bears
two outer spines (armature formula II, I, 4 in legs 2 and 3, and II, I, 3 in leg 4). In the genus
Scottocheres, these armature conditions are shared only with S. laubieri Stock, 1967 and S.
mipoensis Kim, 2016. Otherwise, these two species distinctly differ from the new species
as they have short caudal rami which are as long as wide or wider than long (Stock, 1967;
Kim, 2016) with the third exopodal segment of leg 1 armed with three spines plus four
setae (formula III, 2, 2) rather than two spines plus four setae (armature formula II, 2, 2)
as in the new species.
Regarding the dimension of the caudal ramus, S. nesobius n. sp. appears to be similar to
S. gracilis Hansen, 1923 as the latter species has elongated caudal rami which are five times
longer than wide (Hansen, 1923). Scottocheres gracilis, a deep-sea species known from the
southwest of Iceland, was obscurely described, with unknown leg armature. In S. gracilis,
according to Hansen (1923), the caudal ramus is slightly shorter than the first and second
free abdominal somites combined (‘‘second and third abdominal somites combined’’
according to Hansen) (cf. distinctly longer in the new species). The body of the female
is 1.05 mm long, which is significantly longer than that (about 0.7 mm long) of the new
species. The exopodal segment of leg 5 extends beyond the tooth-like lateral process of the
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 23/26
genital double-somite (cf. the exopodal segment terminates before the process in the new
species).
CONCLUSIONS
Two new genera and four new species of copepods of the family Asterocheridae associated
with sponges are described from the Korean East Sea (Sea of Japan). Hosts and differential
characters of the new copepod species are as follows:
Amalomyzon elongatum n. gen. n. sp. is associated with Dysidea dokdoensis Kang, Lee &
Sim, 2020. It bears an elongated body, two-segmented rami of legs 2, uniramous leg 3 with
a two-segmented exopod, and rudimentary leg 4 represented by a lobe.
Dokdocheres rotundus n. gen. n. sp. is associated with Acanthella vulgata Thiele, 1898. It
has an 18-segmented female antennule, 2-segmented endopod of the antenna, and unusual
setations of swimming legs including the presence of three spines plus four setae on the
third exopodal segment of legs 2–4.
Asterocheres banderaae n. sp. is associated with Petrosia corticate (Wilson, 1925). It bears
no inner coxal seta on leg 1 or 4, but has two strong, sexually dimorphic inner spines on
the second endopodal segment of male leg 3.
Scottocheres nesobius n. sp. is associated with Myxilla producta Hoshino, 1981. It is
characterized by elongate female caudal rami about six times longer than wide, a 17-
segmented female antennule, and an armature of two spines plus four setae on the third
exopodal segment of leg 1.
After adding the two new genera and four new species described here, the family
Asterocheridae in the Korean East Sea now comprises 12 species in seven genera.
ACKNOWLEDGEMENTS
We thank Dr. Jimin Lee (Korea Institute of Ocean Science and Technology) for providing
copepod samples for us to study.
ADDITIONAL INFORMATION AND DECLARATIONS
Funding
This study was supported by a grant (NIBR202227202) from the National Institute of
Biological Resources (NIBR) funded by the Ministry of Environment (MOE) and the Basic
Science Research Program through the National Research Foundation of Korea (NRF)
funded by the Ministry of Education (No. 2021R1I1A2058017), Republic of Korea. The
funders had no role in study design, data collection and analysis, decision to publish, or
preparation of the manuscript.
Grant Disclosures
The following grant information was disclosed by the authors:
National Institute of Biological Resources (NIBR): NIBR202227202.
Ministry of Environment (MOE).
Kim and Lee (2023), PeerJ, DOI 10.7717/peerj.14889 24/26
Basic Science Research Program through the National Research Foundation of Korea
(NRF).
Ministry of Education: 2021R1I1A2058017.
Competing Interests
The authors declare there are no competing interests.
Author Contributions
•Il-Hoi Kim conceived and designed the experiments, performed the experiments,
analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the
article, and approved the final draft.
•Taekjun Lee conceived and designed the experiments, performed the experiments,
authored or reviewed drafts of the article, and approved the final draft.
Data Availability
The following information was supplied regarding data availability:
The morphological characteristics, and taxonomical status of all new species and genera
are available in the ‘Results & Discussion’.
New Species Registration
The following information was supplied regarding the registration of a newly described
species:
Publication LSID: urn:lsid:zoobank.org:pub:0E84F5CE-D4C5-4AAD-A72C-
CCBD77806CDB
Amalomyzon: urn:lsid:zoobank.org:act:214F5279-8986-4F6A-A32E-FD3BCF0EA638
Amalomyzon elongatum: urn:lsid:zoobank.org:act:3CAFD973-9823-4672-8F19-
14665C4D5CFD
Dokdocheres: urn:lsid:zoobank.org:act:6787FECB-E7FA-48DB-97CF-73EBDEB4E151
Dokdocheres rotundus: urn:lsid:zoobank.org:act:AB9D5F75-F663-4593-9058-
5C5CA9F9B02A
Asterocheres banderaae: urn:lsid:zoobank.org:act:670BF905-E285-453E-96C0-
56980A041CE7
Scottocheres nesobius: urn:lsid:zoobank.org:act:4ACBCDB8-4CA4-4803-ABA6-
DAC84F4E7661.
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