Research Article |
Corresponding author: Seong Myeong Yoon ( smyun@chosun.ac.kr ) Academic editor: Alan Myers
© 2016 Tae Won Jung, Jong Guk Kim, Seong Myeong Yoon.
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:
Jung TW, Kim JG, Yoon SM (2016) Two new species of pontogeneiid amphipods (Crustacea, Senticaudata, Calliopioidea) from Korean waters. ZooKeys 635: 53-79. https://doi.org/10.3897/zookeys.635.10604
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Two new pontogeneiid amphipods, Eusiroides pilopalpus sp. n. and Paramoera dentipleurae sp. n., from Korean waters are described and illustrated. Eusiroides pilopalpus sp. n. can be distinguished from congeners by the following characters: mandibular palp article 3 has brush-like setation, maxilla 2 has an inner plate that is not enlarged, and gnathopods 1 and 2 ischium has a well-developed anterior lobe. Paramoera dentipleurae sp. n. can be discriminated from congeners by the following characters: head anterior cephalic lobe is sinusoid, pereopods 5–7 are homopodous and slender, pereopods 6 and 7 basis are proximally lobed but distally diminished on posterior margins, and epimeron 3 is prominently expanded posterodistally.
Amphipoda , Eusiroides pilopalpus , Paramoera dentipleurae , Korea, new species, taxonomy
The family Pontogeneiidae Stebbing, 1906, one of the largest taxa of Calliopioidea Sars, 1895, consists of 31 genera readily distinguishable from its closely related families Cheirocratidae d'Udekem d'Acoz, 2010 and Hornelliidae d'Udekem d'Acoz, 2010 by the presence of calceoli on antennae 1 and 2 (absent in the former), and from the family Calliopiidae Sars, 1895 by a deeply to weakly cleft telson (notched, emarginated or entire in Calliopiidae) (
Members of the genus Eusiroides Stebbing, 1888 share some plesiomorphic characters with littoral marine pontogeneiids such as setose palmar margins of gnathopods, stout homopodous pereopods, and linear, apically setose rami of the uropods (
The genus Paramoera was established by
In Korean waters, three pontogeniids, Eusiroides japonica, Paramoera koreana, and Pontogeneia rostrata Gurjanova, 1938 have been recorded from marine habitats (
Samples were collected from the benthic zones using a sledge net (mesh size 300 µm, mouth size 120 × 45 cm). Specimens were initially fixed with 5% formaldehyde-seawater solution. They were preserved with 85% ethyl alcohol after sorting in the laboratory. Samples were stained with lignin pink dyes. Specimen appendages were dissected in a Petri dish filled with glycerol using dissection forceps and a needle under a stereomicroscope (SZH10; Olympus, Tokyo, Japan). They were mounted onto temporary slides using glycerol-ethanol solution or permanent slides using polyvinyl lactophenol solution. Drawings were performed under a light microscope (LABOPHOT-2; Nikon, Tokyo) with aid of a drawing tube. Definition of the term for ‘seta’ and its types follows those of
Jeju Island, South Korea, 33°14'23"N 126°34'59"E, sublittoral (average depth 24 m).
Holotype: NIBRIV0000328601, adult female, 8.4 mm, collected from the type locality on 30 Nov 2012 by Prof. H.-Y. Soh.
The composite epithet of the specific name of pilopalpus is a combination of Latin pilosus and palpus meaning ‘hairy palp’. This name refers to the character of the mandibular palp article 3: the surface is covered with several rows of minute setae along the distal two-thirds length and with a group of brush-like fine setae at the center of the outer margin. Noun in apposition.
Head with short rostrum; eyes reniform, well-developed. Antennae with stout peduncular articles, with calceoli on flagellum; accessory flagellum of antenna 1 uni-articulate, as long as 1st proximal article of flagellum. Upper lip slightly angulate distally. Lower lip outer lobe with 7 bifid setae on surface. Mandibles both with bi-dentate (1 small and 1 enlarged) incisors, with trifid and 6-dentate lacinia mobilis on right and left mandibles, respectively; palp article 3 covered with numerous fine setae laterodistally. Maxilla 1 outer plate with 10 dentate robust setae apically. Maxilla 2 inner plate broader than outer plate. Maxilliped with short inner plate; outer plate elongate; palp articles 1–3 expanded, article 4 falcate. Gnathopods moderately subchelate, similar to each other, with developed anterior lobe on basis and ischium; dactylus falcate, elongate. Pereopods 3–4 ordinary; basis lined with short setae posteriorly; ischium anterior lobe acute distally; merus anterodistal corner produced bearing 1 robust seta. Pereopods 5–7 basis expanded posteriorly; ischium posterior lobe developed; merus produced posterodistally. Pleonal epimera each with submarginal setae ventrally; epimera 2 and 3 with oblique redge on surface; epimeron 3 with serrations posteriorly. Uropod 1 peduncle with largest seta mediodistally; outer ramus with lateral setae only. Uropod 2 shorter than uropod 1, peduncle with 1 distal seta laterally. Uropod 3 rami lancerolate. Telson shallowly cleft (approximately 1/4 on its length).
Head (Fig.
Eusiroides pilopalpus sp. n., holotype. A Head B Antenna 1 C Calceoli of flagellum on antenna 1 D Antenna 2 E Calceoli of flagellum on antenna 2 F Upper lip G Lower lip H Left mandible I Right mandible J Maxilla 1 K Maxilla 2. Scale bars 0.1 mm (C, E, J, K), 0.2 mm (F–I), 0.5 mm (A, B, D).
Antenna 1 (Fig.
Antenna 2 (Fig.
Upper lip (Fig.
Lower lip (Fig.
Right mandible (Fig.
Left mandible (Fig.
Maxilla 1 (Fig.
Maxilla 2 (Fig.
Maxilliped (Fig.
Gnathopod 1 (Fig.
Gnathopod 2 (Fig.
Pereopod 3 (Fig.
Pereopod 4 (Fig.
Pereopod 5 (Fig.
Pereopod 6 (Fig.
Pereopod 7 (Fig.
Pleonal epimera (Fig.
Uropod 1 (Fig.
Uropod 2 (Fig.
Uropod 3 (Fig.
Telson (Fig.
Oostegites (Fig.
Unknown.
Eusiroides pilopalpus sp. n. is very similar to E. japonica Hirayama, 1985. It can be readily distinguished from E. japonica by the following characteristic features: (1) degree of setation of peduncular articles 4 and 5 on antenna 2 is weaker than that of E. japonica; (2) anterior and posterior margins of peduncular article 5 on antenna 2 are parallel in E. pilopalpus sp. n. (vs. margins are gradually diminish distally, and anterodistal and posterodistal corners are produced in E. japonica); (3) mandibular palp article 3 has a group of brush-like setae on the lateral surface (vs. several rows of minute setae in E. japonica); (4) expanded medial lobe of mandibular palp article 2 is not swollen in E. pilopalpus sp. n. (vs. swollen medially in E. japonica); (5) inner plate on maxilla 2 is not enlarged in E. pilopalpus sp. n. (vs. distinctly enlarged in E. japonica); (6) maxillipedal palp article 3 is covered with fine setae on its distal surface (vs. transverse rows in E. japonica); (7) anterior lobe of ischium on gnathopods 1 and 2 is well-developed in E. pilopalpus sp. n. (vs. moderately developed in E. japonica), (8) acute protrusion at the posterodistal corner of merus on gnathopods 1 and 2 is larger than that of E. japonica; (9) length of the dactylus on gnathopods 1 and 2 is longer than that of E. japonica; (10) posterior lobe of ischium on pereopods 5–7 is acutely produced distally; (11) merus, carpus, and propodus on pereopods 5–7 are more slender than those of E. japonica; (12) both pleonal epimera 1 and 2 have oblique ridges on their lateral surfaces (vs. the ridges are not present in E. japonica) and posterior margin of pleonal epimeron 3 has 11 serrations (vs. seven in E. japonica); (13) the outer ramus on uropod 2 has three dorsal setae medially (vs. dorsal setae are absent in E. japonica); and (14) the distal fourth of the telson is cleft in E. pilopalpus sp. n., (vs. cleft beyond the distal half in E. japonica) (
Eusiroides pilopalpus sp. n. shares several characters with Eusiroides diplonyx Walker, 1909. However, E. diplonyx can be easily discriminated from its congeners because it has stout and round-ended locking setae on pereopods 3 and 4 (
Jeju Island, South Korea, 33°14'23"N 126°34'59"E, sublittoral (average depth 24 m).
Holotype: NIBRIV0000328602, adult female, 7.6 mm, collected from the type locality on 30 Nov 2012 by Prof. H.-Y. Soh.
The composite epithet of the species name of dentipleurae is a combination of Latin dens, Gen. dentis (meaning ‘teeth’ or ‘serration’) and pleurae (indicating ‘pleonal epimera’). Noun in apposition.
Head with short rostrum; lateral cephalic lobes not mammilliform, with sinusoid upper part; inferior antennal sinus forming deep notch, lower margin produced forward; eyes large, reniform. Antenna 1 with stout peduncular articles; accessory flagellum uni-articulate, short, scale-like. Antenna 2 slightly shorter than antenna 1. Lower lip outer lobe with 5 bifid setae mediodistally. Right mandible with 6-dentate incisor and bifid lacinia mobilis. Left mandible with 6-dentate incisor and 5-dentate lacinia mobilis. Maxilla 1 outer plate with 10 dentate robust setae apically; palp bi-articulate, apex beyond apical setae of outer plate. Maxilla 2 inner plate shorter than outer plate. Maxilliped outer plate as long as inner plate, with long serrate setae along apex and medial margins submarginally; palp articles 2 and 3 slender. Gnathopods 1 and 2 moderately subchelate. Gnathopod 1 palm oblique, with robust defining setae of 1, 1, 3 laterally and 2, 3, 1 medially in formulae. Gnathopod 2 palm more oblique than in gnathopod 1, with robust defining setae laterally in formula 1, 2, 1. Pereopods 3–7 dactylus short, with blunt protrusion bearing 1 seta on inner margin, apex curved and claw-like. Pereopods 5–7 elongate and slender. Pereopod 7 basis expanded posteriorly, angulate proximally and diminished distally. Pereonite 7 and pleonites 1–3 carinate dorsally. Pleonal epimeron 1 with 2 naked serrations and 1 weak notch posteriorly; epimeron 2 with 2 serrations bearing 1 minute seta and 1 naked notch posteriorly; epimeron 3 largest, weakly upturned posterodistally, with 5 serrations and 1 distal small notch bearing 1 minute seta posteriorly. Uropod 1 slender; peduncle longer than rami. Uropod 2 shortest. Uropod 3 rami lanceolate, longer than peduncle. Telson deeply cleft (approximately 3/4 length).
Head (Fig.
Paramoera dentipleurae sp. n., holotype. A Head B Antenna 1 C Posterodistal part of peduncular article 1 on antenna 1 D Posterodistal part of peduncular article 2 on antenna 1 E Accessory flagellum F Calceoli of flagellum on antenna 1 G Antenna 2 H Calceoli of flagellum on antenna 2 I Upper lip J Lower lip K Right mandible L Left mandible M Maxilla 1 N Dentate apical setae of outer plate on maxilla 1 O Maxilla 2. Scale bars 0.05 mm (C–F, H–M, O), 0.1 mm (N), 0.2 mm (A, B, G).
Antenna 1 (Fig.
Antenna 2 (Fig.
Upper lip (Fig.
Lower lip (Fig.
Right mandible (Fig.
Left mandible (Fig.
Maxilla 1 (Fig.
Maxilla 2 (Fig.
Maxilliped (Fig.
Gnathopod 1 (Fig.
Gnathopod 2 (Fig.
Pereopod 3 (Fig.
Pereopod 4 (Fig.
Pereopod 5 (Fig.
Pereopod 6 (Fig.
Pereopod 7 (Fig.
Pereonite 7 and pleonites 1–3 (Fig.
Pleonal epimera (Fig.
Uropod 1 (Fig.
Uropod 2 (Fig.
Uropod 3 (Fig.
Telson (Fig.
Unknown.
Paramoera dentipleurae sp. n. is very similar to P. tridentata Bulycheva, 1952 and P. hanamurai Hirayama, 1990 in the following characteristics: (1) the anterior cephalic lobe is sinusoid; (2) pereopods 5–7 are more slender than those of other congeners; (3) the posterior lobe of basis on pereopods 6–7 is largely expanded proximally and diminished distally; (4) epimera 1–3 are carinate dorsally; and (5) epimeron 3 is prominently expanded backward with very similar serration pattern on the posterior margin (
Paramoera dentipleurae sp. n. can be discriminated from P. hanamurai by the following features: (1) upper and lower parts of the inferior antennal sinus do not overlap in P. dentipleurae sp. n.; (2) antenna 1 is longer than antenna 2 in P. dentipleurae sp. n., but antenna 2 is longer than antenna 1 in P. hanamurai; (3) setations of the peduncular articles on antennae 1 and 2 of P. dentipleurae sp. n. are weaker; (4) accessory flagellum has five apical setae in P. dentipleurae sp. n., but it has only two apical setae in P. hanamurai; (5) formulae of the robust defining setae at the palmar corners on gnathopods 1 and 2 are different from each other (1, 1, 3 for lateral setae and 2, 3, 1 for medial setae on gnathopod 1, and 1, 2, 1 for lateral setae in gnathopod 2 in P. dentipleurae sp. n., whereas there are three rows of three setae on the medial surface of gnathopod 1 and without setae on gnathopod 2 in P. hanamurai); (6) posterior margin of basis on pereopod 5 is more expanded distally and the length of the merus is shorter in P. hanamurai; (7) serration patterns are weaker and the posterodistal lobes are indistinct for basis on pereopods 5–7 in P. dentipleurae sp. n. compared to P. hanamurai; (8) each dorsal margin from pereon 7 to pleon 3 has a distal carina in P. dentipleurae sp. n., whereas the distal carina is absent in P. hanamurai; and (9) serration patterns of the posterior margins on the pleonal epimera are simpler in P. hanamurai compared to those in P. dentipleurae sp. n. (
We thank the captain and the crew of the R/V Cheong Gyeong Ho of Chonnam National University for their assistance in sampling. This study was supported by the National Institute of Biological Resources of Korea as a part of the ‘Survey of indigenous biological resources of Korea (