Photis posterolobus
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Ordo: Amphipoda
Familia: Photidae
Genus: Photis
Name
Photis posterolobus Jung & Coleman & Yoon, 2019 sp. nov. – Wikispecies link – ZooBank link – Pensoft Profile
Etymology
The composite epithet of the specific name, posterolobus, is a combination of the Latin words posterus and lobus, referring to the presence of a posterior lobe produced distally on the ischium of male gnathopod 2.
Material examined
Holotype: ♂ (4.8 mm), NIBRIV0000753909. Geomeunyeo, Jeju-do Island, South Korea (33°14'23"N, 126°34'59"E), 24 Dec 2012, grab sampler (about 24 m depth), by Prof. HY Soh.
Diagnosis
Male gnathopod 1 palmar margin weakly sinuated. Male gnathopod 2 basis lateral border forming a well-developed sac-like lobe; ischium posterior margin with lateral lobe acutely produced distally; merus rectangular, stout, half as long as basis, with transparent lobe distally; carpus anterior margin irregular, carpal lobe well developed; propodus stout, as long as basis, posterior margin with one elongate process half as long as anterior margin, palmar margin oblique, 0.7× as long as anterior margin, with two spines (proximal larger than distal), without defining seta. Stridulated ridges only present on gnathopod 2 basis and coxae 3 and 4 in males (unclear in females).
Description
Holotype male. Head (Fig. 18A) as long as pereonites 1 and 2 combined; lateral cephalic lobe rounded; eye circular, moderate in size; located in the middle of lateral lobe; antennal sinus deep. Antenna 1 (Fig. 18B) 0.4× as long as body; peduncle 1st article stout, 0.7× as long as head; 2nd article slender, 1.4× as long as 1st article; 3rd article 0.7× as long as 2nd article; accessory flagellum absent; flagellum 0.8× as long as peduncle 1st–3rd articles combined, composed of ten articles (terminal article rudimentary).
Antenna 2 (Fig. 18C) peduncle 3th article exceeding end of lateral cephalic lobe; 4th and 5th articles as long as 2nd article; flagellum 0.6× as long as peduncle 3rd–5th articles combined, composed of more than six articles.
Upper lip (Fig. 18D) convex anteriorly, with notch in the middle, covered with minute setae.
Mandibles (Fig. 18E, F) with 5-dentate incisor, 4-dentate lacinia mobilis, and four raker setae on left mandible; with 1/2 and 5-dentate incisor, minutely dentate lacinia mobilis, and three raker setae on right mandible; molar well developed, triturative, with seven setae along the distal margin of right mandible; palp asymmetrical, composed of three articles, 3rd article distally rounded, 0.7× as long as 2nd article, with setae extending along most of posteriodistal margin.
Maxilliped (Fig. 19A) inner lobe subrectangular, weakly expanded distally, with three nodular setae apically and one medial nodular seta subdistally; outer lobe exceeding half of palp 2nd article, lined with nine robust setae along apex to medial margin; palp composed of four articles, 3rd article slightly expanded distally, 0.4× as long as 2nd article, 4th article 0.8× as long as 3rd article, with elongate seta apically (1.2× as long as 4th article). Maxilla 1 (Fig. 19B) inner lobe small, covered with minute setae; outer lobe with ten dentate robust setae on apical margin; palp biarticulated, distal article curved, with five setae on apical margin.
Maxilla 2 (Fig. 19C) inner lobe with an oblique row of plumose setae on surface; outer lobe longer and slightly dilated distally than inner lobe.
Gnathopod 1 (Fig. 19D) coxa 0.7× as wide as long, evenly rounded anterioventrally, slightly expanded anteriorly; basis as long as coxa, anterior margin lateral border forming weak lobe distally, with five elongate setae subproximally, posterior margin convex, with five elongate setae at the middle; carpus subtrapezoidal, 0.8× as long as basis, half as wide as long, posterior lobe blunt; propodus as long and wide as carpus, rounded anteriorly, with minute serrations irregularly along palm and posterior margin, palm 0.8× as long as posterior margin, weakly bisinuate, defined by one robust seta medially; dactylus 0.7× as long as propodus, exceeding palm, inner margin serrated, with three teeth.
Gnathopod 2 (Fig. 19E, F) stout, coxa subrectangular, 0.8× as wide as long, produced anterioventrally; basis anterior margin lateral border forming well-developed lobe distally (sac-like lobe reaching middle of carpus) bearing oblique stridulated ridges on surface; ischium anterior lobe small, posterior margin lateral border forming lobe produced distally; merus rectangular, half as long as basis, with transparent lobe distally; carpus anterior margin irregular, carpal lobe well developed; propodus stout, as long as basis, posterior margin with one elongate process half as long as anterior margin, palmar margin oblique, 0.7× as long as anterior margin, with two spines (proximal larger than distal), without defining seta; dactylus 0.7× as long as propodus, with two teeth on inner margin.
Pereopod 3 (Fig. 20A, B) coxa produced anterioventrally, as long as wide, with stridulated ridges on medial surface and short stridulated ridges near the posterioventral corner on lateral surface submarginally; basis 0.3× as wide as long, posterior margin expanded; merus 0.6× as long as basis, anterior margin expanded distally, with two plumose setae submarginally, distal corner weakly produced; carpus half as long as merus, evenly rounded anteriorly; propodus slender, diminished distally, 0.6× as long as basis; dactylus half as long as propodus. Pereopod 4 coxa (Fig. 20C) not widened distally, as long as that of pereopod 3, with stridulated ridges along anterioventral corner oblique.
Pereopod 5 (Fig. 20D–F) coxa bilobed, large, anterior lobe subovoid, expanded ventrally, posterior lobe small, expanded backwards; basis subovoid, broad, more expanded proximally, 0.8× as long as wide; merus subrectangular, slightly convex anteriorly, half as long as basis, 0.4× as wide as long; carpus 0.8× as long as merus; propodus 1.1× as long as carpus, with a pair of distal locking setae unequal in length (longer seta 0.8× as long as dactylus), with a group of four setae (longest seta half as long as propodus) at anteriodistal corner; dactylus half as long as propodus, armed with one accessory cusp on outer margin.
Pereopod 6 (Fig. 20G) 1.1× as long as pereopod 5; coxa bilobed, anterior lobe small, posterior lobe dilated posterioventrally; basis subovoid, 0.8× as wide as long, anterior margin convex, posterior margin slightly dilated proximally; merus 0.6× as long as basis, 0.3× as wide as long; carpus 0.8× as long as merus; propodus 1.2× as long as carpus, with a pair of distal locking setae unequal in length (longer seta 0.6× as long as dactylus), with a group of five setae (longest seta 0.8× as long as propodus) at anteriodistal corner; dactylus half as long as propodus, without accessory cusp on outer margin.
Pereopod 7 (Fig. 20H–I) 1.3× as long as pereopod 6; coxa unilobed, produced posteriorly; basis subovoid, 0.8× as wide as that of pereopod 6, 0.6× as wide as long, anterior margin rather convex, posterior margin with one blunt extension proximally; merus rectangular, 0.7× as long as basis; 0.2× as wide as long; carpus 0.8× as long as merus; propodus 1.5× as long as carpus, with a pair of distal locking setae unequal in length (smaller than those of pereopods 5 and 6), with a group of more than seven setae at posteriodistal corner; dactylus 0.4× as long as propodus, armed with one accessory cusp on outer margin.
Epimeron 1 slightly extended anterioventrally. Epimera 2 and 3 each posterioventral corner produced backwards, but not acute (Fig. 18G).
Uropod 1 (Fig. 20J) peduncle without distoventral spine, with four robust setae on both dorsolateral and dorsomedial margins; inner ramus 0.8× as long as peduncle, with one subapical seta only; outer ramus 0.9× as long as inner ramus, with three dorsolateral setae and one subapical seta.
Uropod 2 (Fig. 20K) 0.8× as long as uropod 1; peduncle 0.7× as long as that of uropod 1; inner ramus 1.1× as long as peduncle, with two dorsal robust setae and one subapical seta; outer ramus 0.9× as long as inner ramus, with two dorsal robust setae and one subapical seta.
Uropod 3 (Fig. 20L) 0.8× as long as uropod 2; peduncle 0.8× as long as that of uropod 2; outer ramus biarticulated, 0.9× as long as peduncle, last article vestigial, with two elongate setae subapically; inner ramus scale-like, 0.4× as long as outer ramus.
Telson (Fig. 20M) subtriangular in dorsal view, with a pair of simple setae, a pair of sensory setae, and one nodular robust seta on each side.
Remarks
Photis posterolobus sp. nov. is closely related to nine Photis species [P. bronca sp. nov.; P. fischmanni Gurjanova, 1951; P. guerrai Tato & Moreira, 2017; P. hawaiensis JL Barnard, 1955; P. kapapa JL Barnard, 1970; P. lecroyae Ortiz, Varela & Lalana, 2011; P. longicaudata (Spence Bate & Westwood, 1863); P. sarae Souza-Filho & Serejo, 2010; and P. tenuicornis GO Sars, 1882] in bearing a very well-developed sac-like lobe anteriodistally on the basis of male gnathopod 2. However, Photis posterolobus sp. nov. can be distinguished from above species by the presence of a posterior lobe produced distally in the ischium of male gnathopod 2 that is absent in the above species (Bate and Westwood 1863[1]; Sars 1883[2]; Gurjanova 1951[3], 1955[4]; Barnard 1955[5], 1970[6]; Ren 2006[7]; Souza-Filho and Serejo 2010[8]; Tato and Moreira 2017[9]).
Original Description
- Jung, T; Coleman, C; Yoon, S; 2019: Taxonomic study on the photid amphipods (Senticaudata, Corophiida, Photoidea, Photidae) from Korean waters, with descriptions of a new genus and seven new species ZooKeys, 886: 1-59. doi
Images
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Other References
- ↑ Bate C, Westwood J (1863) A history of the British sessile-eyed Crustacea, Vol 1.John van Voorst, London, 507 pp. https://doi.org/10.5962/bhl.title.9917
- ↑ Sars G (1883) Oversigt af Norges Crustaceer med foreløbige Bemærkninger over de nye eller mindre bekjendte Arter. I. (Podophtalmata – Cumacea – Isopoda – Amphipoda). Videnskabs-Selskabet i Christiana. 18 [for 1882]: 1–124. [pls. 1-6]
- ↑ Gurjanova E (1951) Bokoplavy morei SSSR i sopredelnykh vod (Amphipoda,Gammaridea).Opredeliteli po faune SSSR, Akademiya Nauk SSSR, Opredeliteli po Faune SSSR41: 1–1029.
- ↑ Gurjanova E (1955) Novye vidy bokoplavov (Amphipoda, Gammaridea) iz servernoi chasti Tixogo Okeana.Zoologicheskogo Instituta Akademii Nauk SSSR, Trudy18: 166–218.
- ↑ Barnard J (1955) Gammaridean AmphipodaCrustacea in the collections of Bishop Museum.Bernice Pauahi Bishop Museum bulletin215: 1–46.
- ↑ Barnard J (1970) Sublittoral Gammaridea (Amphipoda) of the Hawaiian Islands.Smithsonian Contributions to Zoology34: 1–286. https://doi.org/10.5479/si.00810282.34
- ↑ Ren X (2006) Fauna Sinica, Invertebrata Vol 41, Crustacea, Amphipoda, Gammaridea (I).Science Press, Beijing, 558 pp.
- ↑ Souza-Filho J, Serejo C (2010) Two new species of the family Photidae (Amphipoda: Corophiidea: Photoidea) from Brazilian waters, with description of Rocasphotis gen. nov.Journal of Natural History44: 59–577. https://doi.org/10.1080/00222930903471118
- ↑ Tato R, Moreira J (2017) Two new species of the Suborder Senticaudata (Crustacea: Amphipoda) from the upper continental slope off Galicia (NW Iberian Peninsula).Zootaxa4300: 217–237. https://doi.org/10.11646/zootaxa.4300.2.4
