Research Article |
Corresponding author: Wonchoel Lee ( laophonte@gmail.com ) Academic editor: Danielle Defaye
© 2017 Jinwook Back, Wonchoel Lee.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Back J, Lee W (2017) Two new species of Leptopsyllus from Korea (Copepoda, Harpacticoida, Paramesochridae). ZooKeys 665: 37-57. https://doi.org/10.3897/zookeys.665.6150
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Two new species of Leptopsyllus are described from the subtidal zone of Korea. Both species were assigned to the subgenus Leptopsyllus (Leptopsyllus) T. Scott, 1894, based on following three characters: two-segmented rami of P1, absence of endopod on P2 and P3, and presence of one-segmented endopod of P4. L. (L.) pundiussp. n. is most closely related to L. (L.) punctatus Mielke, 1894, however clearly distinguishable from it based on mandibular exopod with two setae, shape of P6, and caudal seta III ornamented with spinules in the new species. L. (L.) koreanussp. n. is clearly distinguishable from its congeners by the second segment of P1 endopod armed with one element, male baseoendopod of P5 with one seta, and one segmented endopod of mandibular palp. The world distribution and updated key to the species of the genus Leptopsyllus are provided.
Copepoda , Harpacticoida , Korea, Leptopsyllus , Paramesochridae , taxonomy
Although the marine biodiversity of Korea is very high according to a recent estimation (
Paramesochrid harpacticoids, with their reduced appendages and vermiform body shapes, successfully inhabit subtidal and intertidal sandy bottoms (
Thomas
A survey of harpacticoid copepods from subtidal zones in Korea resulted in the discovery of two new species belonging to Leptopsyllus (Leptopsyllus). Here these two species are described and an updated key to species of the genus is provided.
Specimens were collected from sediments in the subtidal zone near Pung Island off the west coast of Korea (Leptopsyllus (Leptopsyllus) pundius sp. n.), and Maemul Island (Leptopsyllus (Leptopsyllus) koreanus sp. n.) off the south coast of Korea. Sediments were collected using a grab (surface area 0.1 m2) and fixed with 5% buffered formalin. Copepods were extracted from the sediment samples using the Ludox method (
The descriptive terminology of
A1 antennule;
A2 antenna;
ae aesthetasc;
exp exopod;
enp endopod;
P1–P6 first to sixth thoracopod;
exp (enp)-1 (2, 3) to denote the proximal (middle, distal) segment of a three-segmented ramus;
CR caudal ramus.
Specimens were deposited in the National Marine Biodiversity Institute of Korea (MABIK). Scale bars in figures are in μm.
Paramesochridae. Body cylindrical, depressed dorsoventrally; with distinct separation between prosome and urosome; rostrum fused with cephalothorax. Caudal ramus with 5–7 setae. Antennule 7- or 8-segmented in female, subchirocer in male. Antennary exopod 1-segmented (except for L. (L.) dubatyi, 2-segmented) with 3–5 setae. Maxilla with 3 endites on syncoxa; endopod 1-segmented. Maxilliped with elongate basis; endopod 1- or 2-segmented. P1 biramous, 2-segmented endopod and exopod. P2 uniramous; without endopod; with 3-segmented exopod, except for L. (L.) abyssalis with 2-segmented exopod. P3 uniramous; without endopod, except for L. (P.) arcticus with 1-segmented endopod; with 3-segmented exopod, except for L. (L.) abyssalis with 2-segmented exopod. P4 biramous; with 1-segmented endopod; with 3-segmented exopod, except for L. (L.) abyssalis with 2-segmented exopod. P1–P4 armature formulae:
Exopod of P5 armed with 3 setae in both sexes.
Sexual dimorphisms in A1, P5, P6 and genital segment.
Leptopsyllus (Leptopsyllus) typicus T. Scott, 1984
L. (L.) paratypicus Nicholls, 1939; L. (L.) reductus Lang, 1948; L. (L.) harveyi Wells, 1963; L. (L.) elongatus Drzycimski, 1967; L. (L.) dubatyi Soyer, 1974; L. (L.) abyssalis Becker, Noodt & Schriever, 1979 ; L. (L.) platyspinosus Mielke, 1984; L. (L.) punctatus Mielke, 1984; L. (L.) celticus Bodin & Jackson, 1987; L. (L.) pundius sp. n.; and L. (L.) koreanus sp. n.
Republic of Korea, Pung Island (Korean name Pungdo): subtidal zone, 37°5'21.46"N, 126°24'27.10"E (depth: 30 m, sand).
Holotype 1♀ (MABIK CR00235287) dissected on four slides. Sampled by a grab on a fishing boat on 16 Feb 2008.
Description of female. Total body length 390 µm (Fig.
Genital field located mid-ventrally halfway the length of the genital double-somite; copulatory pore located near posterior border of genital field and covered by small process (Fig.
CR (Fig.
A1 (Fig.
A2 (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2, P3 (Fig.
P4 (Fig.
Armature formula as follows:
P5 (Fig.
Description of male. Unknown.
The specific name refers to the type locality of the new species, Pung Island, Korea.
Republic of Korea, Maemul Island (Korean name : Maemuldo), subtidal zone off 37° 37'43.38"N, 128° 46'24.51"E (depth: 50 m, muddy sand).
Holotype 1♂ (MABIK CR00235288) dissected on four slides. Sampled by a grab on a fishing boat on 23 Feb 2011.
Description of female. Unknown.
Description of male. Total body length 575 µm; largest width measured at posterior margin of cephalic shield: 105 µm (Fig.
CR (Fig.
A1 (Fig.
A2 (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2, P3 (Fig.
P4 (Fig.
Armature formula as follows:
P5 (Fig.
P6 (Fig.
The specific name refers to the type locality of the new species in Korea.
Since the genus Leptopsyllus was proposed by Scott T (1894) based on the reduction of legs, several species have been described in Leptopsyllus. Though many species were originally assigned to the genus Leptopsyllus, some of them were moved to new genera according to new classifications based on leg characteristics (reduced or absent).
Until now, many species belonging to genus Leptopsyllus have been found mainly in Europe in Atlantic Ocean (Fig.
The two new species are placed in the genus Leptopsyllus T. Scott, 1894 based on the absence of an endopod on P2 and P3, P4 endopod armed with one apical seta, and presence of two setae/spines on the distal segments of the exopods on P2–P4. The two new species are placed in subgenus Leptopsyllus on account of the absence of P3 endopod because the discrepancy in the diagnostic characters between the subgenera Leptopsyllus T. Scott, 1894 , and Paraleptopsyllus Lang, 1944 is presence or not of P3 endopod.
Leptopsyllus (L.) pundius sp. n. is closely related to L. (L.) punctatus Mielke, 1984 based on combination of three characters: (1) body length, (2) one segment of A2 exopod with 4 setae, (3) P5 exopod separated with the baseoendopod, and 4) the baseoendopod well developed armed with 2 setae (Table
Morphological characters of Leptopsyllus (Leptopsyllus). Four groups were distinguished by the feature of the female P5.
Group | Species name | Body Size | A2 | Swimming legs | P5 | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
P1 | P2 | P3 | P4 | ||||||||||
Female (Male) |
No. of exp seg. (total No. of setae) |
Enp-2 | Exp-1 | Exp-2 | Exp-2 | Exp-2 | Exp-3 | Enp-1 | Enp-2 | Exp. separation | Benp. develope (No. of setae) |
||
1 | abyssalis | 730 | 1(5) | 011 | 0 | 021 | 021 | 021 | · | 010 | · | F | N(0) |
reductus | 500 | ?(4) | 011 | 0 | 0 | 0 | ? | ? | 0 | 010 | F | N(0) | |
2 | platyspinosus | 400–440 (360) |
1(4) | 011 | 0 | 0 | 0 | 0 | 011 | 010 | · | S | N(0) |
3 | celticus | 380–400 | 1(4) | 011 | 0 | 1 | 1 | 0 | 021 | 010 | · | F | D(2) |
4 | dubatyi | 400–445 | 2(4) | 011 | 0 | 0 | 0 | 0 | 011 | 010 | · | S | D(0) |
harveyi | 420 | 1(3) | 011 | 0 | 0 | 0 | 0 | 021 | 010 | · | S | D(0) | |
punctatus | 290–390 (280–380) |
1(4) | 011 | 0 | 0 | 0 | 0 | 011 | 010 | · | S | D(2) | |
typicus | 700 | 1(4) | 011 | ? | ? | 0 | 0 | 011 | 0 | 010 | S | D(2) | |
pundius sp. n. | 390 | 1(4) | 011 | 0 | 0 | 0 | 0 | 011 | 010 | · | S | D(2) | |
Unknown | elongatus | (900) | 1(5) | 010 | 0 | 0 | 0 | 0 | 011 | 010 | · | ? | ? |
paratypicus | (360) | 1(4) | 011 | 1 | 1 | 1 | 0 | 011 | 010 | · | male only | male only | |
koreanus sp. n. | (575) | 1(4) | 010 | 0 | 0 | 0 | 0 | 011 | 010 | · | male only | male only |
The description of L. (L.) koreanus sp. n. is based on a single male specimen. Although we are not able to compare L. (L.) koreanus sp. n. with its congeners based on female characters, the new species has clear morphological differences from its congeners: (1) single seta on the second segment of the P1 endopod; only one species in the subgenus Leptopsyllus, L. (L.) elongates Drzycimski, 1967, shares this character with L. (L.) koreanus, (2) a single seta on the baseoendopod of P5 in male; this is a unique character in the subgenus Leptopsyllus, and (3) one-segmented endopod of the mandibular palp; L. (L.) koreanus sp. n. shares this character with L. (L.) platypinosus Mielke, 1984. The caudal ramus in the genus Leptopsyllus is conical and its distal margin is bluntly pointed; however, caudal seta formula varies among congeners. Leptopsyllus (L.) koreanus sp. n. clearly has caudal seta I, although this seta is obscure in other congeners. Both new species have a tri-articulated seta VII, while L. (L.) punctatus and L. (L.) platyspinosus have a bi-articulated seta VII arising from a chitinous outgrowth on the dorsal surface. However, the caudal rami and setae of other species in Leptopsyllus have not been described in detail in other previous studies.
Four distinctive groups within the genus Leptopsyllus can be recognized based on the shape of the female P5 (Table
The latest key proposed by Bodin & Jackson (1987) includes nine species of Leptopsyllus, and does not include the two species L. (P.) arcticus and L. (L.) abyssalis. Because only the males of some species have been described, the extent of sexual dimorphism in mouthparts or P1–P4 was not known. An updated key is developed on the basis of selected characteristics from the original description that identifies species within the genus Leptopsyllus.
1 | P3 endopod 1-segmented | (Subgenus Paraleptopsyllus)...L. (P.)arcticus |
– | P3 endopod absent | (Subgenus Leptopsyllus)...2 |
2 | P2–P4 exopod 2-segmented | L. (L.) abyssalis |
– | P2–P4 exopod 3-segmented | 3 |
3 | Distal segment of P1 endopod with 1 seta | 4 |
– | Distal segment of P1 with 2 elements | 5 |
4 | A2 exopod with 5 setae; caudal ramus with 5 setae | L. (L.) elongatus |
– | A2 exopod with 4 setae; caudal ramus with 7 setae | L. (L.) koreanus sp. n. |
5 | Middle segments of P2 and P3 exopod with 1 inner element | 6 |
– | Middle segment of P2 and P3 exopod without inner element | 7 |
6 | Male exopod of P5 with 3 setae | L. (L.) paratypicu s |
– | Male exopod of P5 with 4 setae | L. (L.) celticus |
7 | A2 exopod 2-segmented | L. (L.) dubatyi |
– | A2 exopod 1-segmented | 8 |
8 | A2 exopod with 3 setae | L. (L.) harveyi |
– | A2 exopod with 4 setae | 9 |
9 | P5 endopodal lobe flattened | 10 |
– | P5 endopodal lobe well developed | 11 |
10 | P5 exopod separated, caudal seta III modified | L. (L.) platyspinosus |
– | P5 exopod fused with baseoendopod | L. (L.) reductus |
11 | Each P5 baseoendopodal lobe divided in middle; P1exp-1 with 2 outer setae | L. (L.) typicus |
– | Each P5 baseoendopodal lobe without median incision; P1exp-1 with 1 outer seta | 12 |
12 | Caudal seta III stout and decorated with spinules defined at base; each side of P6 with 1 seta | L. (L.) pundius sp. n. |
– | Caudal seta III cylindrical, decorated with long spinules; each side of P6 with 3 setae | L. (L.) punctatus |
This research was supported by Securement, Analysis and Evaluation of Marine Invertebrate Bioresources (MABIK 20w17M00600) sponsored by the National Marine Biodiversity Institute of Korea.