Maxillipius koreanus, Lee & Kim & Kim, 2025
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https://doi.org/10.11646/zootaxa.5717.2.6 |
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publication LSID |
lsid:zoobank.org:pub:2EF3F22B-7B84-4023-A5BA-C82CC7818272 |
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DOI |
https://doi.org/10.5281/zenodo.17890338 |
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persistent identifier |
https://treatment.plazi.org/id/5B2AE879-FFEC-7000-FF3D-D803FD70FAA6 |
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Plazi |
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Maxillipius koreanus |
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sp. nov. |
Maxillipius koreanus sp. nov. ( Figs. 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )
(Korean name: Han-guk-gin-da-ri-yeop-sae-u, new)
Type material. Holotype, adult male, 2.5 mm, MABIK CR00259499 , Gadeokdo-dong , Gadeokdo, Gangseo-gu, Busan, Korea, 35°00′44"N, 128°49′33"E, 7 June 2024, collected using Light traps by K.W. Kim GoogleMaps . Paratypes, adult female, 2.4 mm, MABIK CR00259500 , data same as holotype. The remaining paratypes ( 43 ♂, 23 ♀, 32 inds., DKUAMP202512) in the collection of the corresponding author GoogleMaps .
Additional material examined. 12 inds. Yeongil-dong , Udo-myeon, Jeju, Korea, 33°30'11"N, 126°58'07"E, collected using Light traps, Y.H. Kim, 28 May 2024 GoogleMaps .
Etymology. The new species is named for its occurrence in Korea.
Description. Holotype adult male, MABIK CR00259499.
Body ( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 ) small, 2.5 mm long, pereonites dorsally smooth, pleonites 1–2 carinate dorsodistally; head subquadrate, subequal in length to pereonites 1–3 combined; eye medium, subcircular, lateral cephalic lobe indistinct; pereonites 1–6 short, pereonite 7 longest; pleonites 1–2 ( Fig. 3B View FIGURE 3 ) with posterodorsal teeth, preceding tooth blunt, divided into two by a shallow notch; succeeding tooth narrow, with a small notch at the apex; epimeral plates 1–3, posteroventral corner minutely pointed.
Antenna 1 ( Fig. 3C View FIGURE 3 ) elongate, sexually dimorphic; peduncular articles 1–2 short, subequal in length; peduncular article 3 subquadrate laterally, while medial portion extends into a pointed projection, with several rows of callynophores, fused with flagellum article 1; accessory flagellum absent; flagellum elongate, 25-articulate.
Antenna 2 ( Fig. 3D View FIGURE 3 ), peduncular articles 2–3 short, peduncular article 4 subrectangular, peduncular article 5 slender, longest; flagellum elongate, 41-articulate.
Upper lip ( Fig. 3E View FIGURE 3 ) ovate, apex pubescent.
Lower lip ( Fig. 3F View FIGURE 3 ), inner lobe well developed, apex with pubescence; outer lobe covered with pubescence apically, mandibular process produced, acute distally, slightly curved.
Left mandible ( Fig. 3G View FIGURE 3 ), incisor with 10 teeth; lacinia mobilis with 6 blunt teeth; accessory setal row with 3 pectinate setae; molar triturative with a seta; palp absent, replaced by a small simple seta.
Right mandible ( Fig. 3H View FIGURE 3 ) similar to left mandible, incisor with 9 teeth; lacinia mobilis with over 16 serrated teeth; accessory setal row with 2 pectinate setae.
Maxilla 1 ( Fig. 3I View FIGURE 3 ), inner plate reduced; outer plate subrectangular with 10 multi-cusped setal-teeth of which the 2 ones are nodular; palp large, broadening distally, uniarticulate, with 5 robust setae on apically, 13 long setae laterodistally.
Maxilla 2 ( Fig. 3J View FIGURE 3 ), inner plate subrectangular, with 2 medial setae and 6 apical setae; outer plate slightly longer than inner plate, with 8 lateral setae and 7 apical setae.
Maxilliped ( Fig. 3K View FIGURE 3 ), inner plate narrow with 2 apical setae; outer plate subovate, reaching the half of palp article 2, with 10 simple setae apicomedially; palp 4-articulate, article 1 short, bearing a pinnate seta mediodistally, article 2 greatly expanded, with marginal and submarginal setae, article 3 longish ovate, curved medially, with long simple setae on the laterodistal region, article 4 falcate, with 3 small setae.
Gnathopod 1 ( Fig. 4A View FIGURE 4 ) subchelate; coxa vestigial; basis subrectangular, anterior margin with 4 short setae, posterodistal margin nearly bared, with 1 distal seta; ischium short; merus subrectangular, extending posterodistally on half of carpus, with 6 simple setae posterodistally; carpus subtriangular, expanding distally, 11 simple setae posteriorly; propodus subovate, palm oblique, with rows of simple setae; dactylus falcate; length ratio of articles 2–7 = 1.00: 0.17: 0.29: 0.62: 0.50: 0.29.
Gnathopod 2 ( Fig. 4B View FIGURE 4 ) simple, longer than gnathopod 1; coxa subovate, tapering anteroventrally with rounded corner; basis subrectangular, elongate; ischium and merus short; carpus elongate, slightly convex anteriorly, with several setae posteriorly; propodus characteristic in form, without palm, longish elliptical, distal two-thirds of posterior margin with a row of bicuspidate setae and two rows of simple setae submarginally; dactylus falcate; length ratio of articles 2–7 = 1.00: 0.12: 0.18: 1.00: 0.76: 0.29.
Pereopod 3 ( Fig. 4C View FIGURE 4 ), coxa subquadrate, wider than long; basis elongate, subrectangular; ischium short; merus subrectangular, slightly widening distally; carpus subrectangular, slightly convex; propodus elongate, subrectangular, anterior margin with 5 unequal simple setae, posterior margin with 5 simple setae, distally setose; dactylus falcate, with a nail, posterior margin with setules; length ratio of articles 2–7 = 1.00: 0.15: 0.40: 0.79: 1.12: 0.59.
Pereopod 4 ( Fig. 4D View FIGURE 4 ) similar to pereopod 3; length ratio of articles 2–7 = 1.00: 0.21: 0.43: 0.90: 1.21: 0.64.
Pereopod 5 ( Fig. 4E View FIGURE 4 , left,) subsimilar to both pereopods 3 and 4, but inverted, more elongated; coxa subquadrate, wider than long; basis subrectangular, ridged posterodistally; carpus to propodus elongate, rectangular, length ratio of articles 2–7 = 1.00: 0.20: 0.65: 1.38: 2.00: 0.80.
Pereopod 6 ( Fig. 4F View FIGURE 4 ) characteristic in form, extremely elongate; coxa trapezoidal; basis subovate, posterodistally extending beyond end of ischium with triangular corner, anterior margin with 2 simple setae, posterior margin with 3 simple setae; ischium short, compressed; merus subovate, broad, subequal in size to basis; carpus slender, rectangular, both margins with 2 short setae; propodus extremely elongate, whip-like form, gradually narrowing distally, both margins with a row of short setae; dactylus indistinct; length ratio of articles 2–6 = 1.00: 0.19: 0.75: 1.56: 12.31.
Pereopod 7 ( Fig. 4G View FIGURE 4 ) subsimilar to pereopod 5, but coxa small, subovate; basis subovate, broad, posterodistal corner acutely produced; carpus to propodus moderately setose; length ratio of articles 2–7 = 1.00: 0.21: 0.56: 1.32: 1.63: 0.47.
Uropod 1 ( Fig. 4H View FIGURE 4 , left) peduncle slender, rectangular, with 4 robust setae dorsolaterally, 2 robust setae dorsomedially, apicolateral corner with 1 process; rami lanceolate, with lateral and medial setules; outer ramus × 0.59 peduncle, with 2 simple setae laterally; inner ramus longer, about 1.46 × outer ramus.
Uropod 2 ( Fig. 4I View FIGURE 4 ) subsimilar to uropod 1, but peduncle shorter than that of uropod 1, with 1 dorsolateral and 1 apicomedial robust seta; outer ramus short, × 0.84 peduncle, with 1 lateral seta; inner ramus longer, about 1.88 × outer ramus.
Uropod 3 ( Fig. 4I View FIGURE 4 ) subsimilar to uropod 2; peduncle unarmed, subequal in length to outer ramus; outer ramus slightly short than inner one.
Telson ( Fig. 4I View FIGURE 4 ) suboval, entire, wider than long, width 1.7 × length, with 4 short setae subdistally.
Paratype, adult (ovigerous) female, MABIK CR00259500 .
Body ( Figs. 2B View FIGURE 2 , 5A View FIGURE 5 ) about 2.4 mm long; similar to male; slightly depressed dorsoventrally; coxae 2 ( Fig 5C View FIGURE 5 ) –5 more expended than those of male.
Antenna 1 ( Fig. 5B View FIGURE 5 ) showing sexual dimorphism, peduncular article 3 without mediodistal projection and callynophore, several ventrodistal aesthetascs on flagellum articles.
Variation. Body length at maturity of male is 2.5 mm and female is 2.4 mm, based on an ovigerous specimen. The number and shape of dorsal teeth on pleonites 1 and 2 in female exhibit age variation. In this mature female ( 2.4 mm), pleonite 1 ( Fig. 5D View FIGURE 5 ) with 2 dorsal teeth and pleonite 2 posterodorsal tooth with apical notch. Subadult female ( 1.8 mm), however, pleonite 1 ( Fig. 5E View FIGURE 5 ) with 2 dorsal teeth and pleonite 2 posterodorsal tooth without notch. On the other hand, juvenile ( 1.6 mm), pleonite 1 ( Fig. 5F View FIGURE 5 ) dorsal tooth underdeveloped and pleonite 2 posterodorsal tooth without apical notch.
Molecular data. CO1 gene sequences (GenBank accession numbers PV535648, PV535649, PV535650, PV535651, PV540241, PV540243) were obtained from six specimens of Maxillipius koreanus sp. nov. These sequences were aligned and compared with sequences from M. rectitelson (PV535652, PV535653, PV540242) ( Table 1). The intraspecific variation of the CO1 gene sequence of M. koreanus sp. nov. ranged from 0.0% to 1.0%, indicating genetic homogeneity within the species. In contrast, the interspecific variation ranged from a low of 21.4% to a high of 22.7% (between M. koreanus sp. nov. and M. rectitelson ) ( Fig. 9 View FIGURE 9 , Table 2).
Remarks. Among the two known species of Maxillipius , the newly identified species, Maxillipius koreanus sp. nov. is similar to M. rectitelson in having the following characteristics: 1) pleonites 1–2 with posterodosal process; 2) gnathopod 1, carpus subtriangular with a posterior lobe; 3) gnathopod 1, propodus subovate. However, M. koreanus sp. nov. is distinguished from M. rectitelson based upon the following features (different characters of M. rectitelson in brackets): 1) pleonite 2, posterodorsal tooth with an apical notch ( vs. without notch); 2) female gnathopod 1, basis posteriorly bare ( vs. with three posteromarginal setae); 3) gnathopod 2, coxa trapezoidal, narrowing anteroventrally ( vs. subrectangular, anterior margin blunt); 4) gnathopod 2 simple, propodus without palm ( vs. subchelate, with palm); 5) gnathopod 2, posterior margin of propodus with bicuspidate setae and simple setae ( vs. with simple setae); and 6) pereopods 3–5 and 7, dactyli posterior margins without serrulation ( vs. with serrulation).
To validate this distinction, molecular sequences of the COI gene from both previously identified and newly identified samples of M. koreanus sp. nov. and M. rectitelson in Korea were compared and analyzed ( Fig. 9 View FIGURE 9 , Table 2). Based on these morphological and genetic differences, we conclude that M. koreanus sp. nov. represented a novel species.
Distribution. Korea ( Busan, Udo Island).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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