Ceradocus kiiensis, Ariyama, 2019

Ariyama, Hiroyuki, 2019, Two species of Ceradocus collected from coastal areas in Japan, with description of a new species (Crustacea: Amphipoda: Maeridae), Zootaxa 4658 (2), pp. 297-316 : 300-302

publication ID	https://doi.org/ 10.11646/zootaxa.4658.2.5
publication LSID	lsid:zoobank.org:pub:C90D9081-2857-44A8-9850-86C79A5D14CC
persistent identifier	https://treatment.plazi.org/id/63B14ABB-356C-4607-884A-2C37F771DF3D
taxon LSID	lsid:zoobank.org:act:63B14ABB-356C-4607-884A-2C37F771DF3D
treatment provided by	Plazi
scientific name	Ceradocus kiiensis
status	sp. nov.

Treatment

Ceradocus kiiensis sp. nov.

[Japanese name: Kii-nokogiriyokoebi, new]

( Figs 2–6 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Type material. Holotype: male, 7.4 mm (OMNH-Ar-11271), Ena, Yura Town , Wakayama Prefecture, 33°59'36"N, 135°06'13"E ( Fig. 1A View FIGURE 1 ), 0.5 m depth, stones and coarse sand bottom, 21August 2017, coll. H. Ariyama. GoogleMaps Paratypes: male, 4.3 mm (OMNH-Ar-11272), same data as holotype; male, 5.6 mm (OMNH-Ar-11273), Kuroshima Island, Yura Town , Wakayama Prefecture, 34°00'12"N, 135°05'30"E ( Fig. 1A View FIGURE 1 ), 4 m depth, coarse sand bottom, 2 August 2008, coll. H. Ariyama; female, 6.6 mm (OMNH-Ar-11274), same data as paratype, male, 5.6 mm (OMNH-Ar- 11273) except for habitat, 1 m depth, under stones GoogleMaps .

Type locality. Ena , Yura Town in Wakayama Prefecture, Japan .

Etymology. Referring to the type locality. “Kii” is an old name of Wakayama Prefecture.

Diagnosis. Male gnathopod 2 asymmetrical; larger male gnathopod 2 with strongly oblique palm having single shallow excavation and never having defining cusp; smaller male gnathopod 2, palm oblique, smooth, defined by tiny projection. Pereopods 5–7, bases with acute posterodistal lobe. Pleonites 1–3 with many dorsal teeth, epimera 1 – 3 each bearing posterior, posteroventral and ventral teeth. Urosomites 1–3 with 9, 4, 2 dorsal teeth, respectively. Uropod 3 enlarged, both rami wide. Telson , each lobe with 1 long and 1 – 2 short robust setae.

Description. Based on holotype, male, 7.4 mm (OMNH-Ar-11271), and paratype, female, 6.6 mm (OMNH- Ar-11274) for upper lip.

Head ( Figs 2–3 View FIGURE 2 View FIGURE 3 ). Eyes relatively large, about 0.3 times as long as head. Antenna 1 about 0.6 times as long as body, poorly setose; peduncle with ratio of lengths of articles 1–3 1:1.15:0.2, article 1 with 4 posteromedial robust setae, anterodistal corner with bundle of setae; accessory flagellum short, with 5 articles, terminal article minute, length about 0.15 times primary flagellum; primary flagellum long, with 32 articles, terminal article minute. Antenna 2 about half length of antenna 1, weakly setose, with ratio of lengths of peduncular articles 3–5 1:2.2:1.9; flagellum short, with 15 articles, terminal article minute. Upper lip, ventral margin rounded, with short setae. Mandible, each incisor bearing 4 cusps, left lacinia mobilis 4-dentate, with 9 accessory setae, right lacinia mobilis bifid, 5-dentate, with 8 accessory setae, each molar developed; palp articles 1 – 3 length ratio (excluding distal tooth of article 1) 1:2.05:0.85, articles 2 – 3 weakly setose. Lower lip, distal margins of inner and outer lobes setose, mandibular processes small. Maxilla 1, inner plate heavily setose on mediodistal margin, outer plate with 9 apical robust setae, palp with many apical setae. Maxilla 2, outer plate same size as inner plate; outer plate bearing many apical setae, inner plate heavily setose on mediodistal margin and dorsomedial surface. Maxilliped, inner plate truncate, distally setose, distomedial corner with 3 robust setae ventrally; outer plate with 13 long-to-short robust setae on distomedial margin; palp 4-articulate, articles 2 – 3 setose medioventrally, article 4 with large apical robust seta.

Pereon ( Fig. 4 View FIGURE 4 ). Gnathopod 1, coxa ventral margin with several short setae; basis short, with 3 long setae on posterior margin, 5 setae on posteromedial surface and 3 thick setae on posterodistal margin; merus setose posteriorly; carpus longish trapezoidal, posterior margin and medial surface heavily setose; propodus longish ovate, slightly shorter than carpus, anterodistal corner and posterior margin setose, palm oblique, posterior margin lined with 4 large and many short robust setae; dactylus slender, slightly curved posteriorly. Gnathopod 2 asymmetrical, carpus–dactylus different between right and left; coxa subquadrate, ventral margin with several setae, gill large, roundish, subequal to basis length; basis posterior margin bearing 2 long and 2 short setae, lateral surface with anterodistal ridge; merus with acute posterodistal spine; right carpus triangular, lobate and setose posterodistally; right propodus longish ovate, about 3.9 times as long as carpus, length about twice of width, palm strongly oblique, posterior margin smooth except for distal shallow excavation, with many marginal and medio-submarginal robust setae; right dactylus stout, curved posteriorly, inner margin with hollow proximally; left carpus longer than right one, heavily setose posterodistally; left propodus slender, about 1.7 and 0.65 times as long as carpus and right propodus, respectively, length about 2.1 times width, anterodistal corner and posterior margin weakly setose, palm oblique, defined by tiny projection with robust seta, posterior margin bearing many marginal and 4 long medio-submarginal robust setae; left dactylus slender.

Pereopods 3–4 subequal in shape, pereopod 3 about 1.1 times length of pereopod 4; coxae subtrapezoidal, anterior and ventral margins with a few short setae, ventromedial surfaces bearing long seta, gills large; bases rectilinear, posterior margins with 5 long setae; meri – propodi with marginal robust and slender setae; dactyli short. Pereopod 5 about 1.35 times length of pereopod 4; coxa with robust seta on posteroventral margin; basis subrectangular, length about 1.9 times width (excluding posterodistal lobe), posterodistal corner sharply projected, anterior margin bearing long and short robust setae, lateral surface with ridge; merus – propodus with marginal robust setae, dactylus short. Pereopod 6 about 1.3 times as long as pereopod 5; coxa with 4 robust setae on anteroventral margin; basis subrectangular, length about 1.75 times width (excluding posterodistal lobe), posterodistal corner sharply projected, anterior margin bearing long and short robust setae, lateral surface with ridge; merus – propodus with marginal robust setae, dactylus short. Pereopod 7 slightly shorter than pereopod 6; coxa with robust seta on anteroventral margin; basis subrectangular, length about 1.85 times width (excluding posterodistal lobe), posterodistal corner sharply projected, anterior margin bearing short robust setae, lateral surface with ridge; merus – propodus with marginal robust setae, dactylus short.

Pleon ( Figs 2 View FIGURE 2 , 5 View FIGURE 5 ). Pleonites 1–3 with 25, 21, 21 dorsal teeth, respectively; epimeron 1 bearing 4 posterior, 1 posteroventral and 4 ventral teeth, 2 ventral robust setae and lateral ridge; right epimeron 2 (left one abnormal) with 8 posterior, 1 posteroventral and 4 ventral teeth, 2 ventral robust setae and lateral ridge; epimeron 3 with 10 posterior, 1 large posteroventral and 5 ventral teeth and 2 ventral robust setae. Urosomite 1 bearing 9 continuous dorsal teeth, midline with 1 tooth and each dorsolateral margin with 4 teeth. Urosomite 2 with midline gape, each dorsolateral margin with 2 teeth. Urosomite 3 with wide midline gape, each dorsolateral corner bearing tiny tooth. Pleopods 1–3, pleopod 3 shortest; peduncles with 2 coupling hooks and 2 short setae distally, peduncles of pleopods 1 – 2 bearing a few and many setae, respectively, peduncle of pleopod 3 with many proximal setae and several lateral and distal robust setae; both rami almost same length, outer rami with 20, 20, 18 articles and inner rami with 18, 19, 17 articles respectively. Uropod 1, peduncle with large basofacial and distolateral robust setae and 8 dorsolateral and 7 dorsomedial robust setae; outer ramus slightly shorter than inner ramus, about 0.8 times as long as peduncle, with 3 lateral, 3 medial and 5 terminal robust setae; inner ramus with 6 lateral, 6 medial and 5 terminal robust setae. Uropod 2 about 0.65 times length of uropod 1; peduncle bearing 3 dorsolateral and 2 dorsomedial robust setae, distolateral corner with 2 dorsal and 1 ventral robust setae, distomedial corner bearing 2 robust setae dorsally; outer ramus about 0.9 times length of inner ramus, about 1.2 times as long as peduncle, with 5 lateral, 1 medial and 5 terminal robust setae; inner ramus with 9 medial and 5 terminal robust setae. Uropod 3 about 1.55 times as long as uropod 2; peduncle projected proximally, lateral surface with 1 dorsal, 3 dorsodistal and 2 ventrodistal robust setae, medial surface bearing 7 dorsal and 3 distal robust setae; outer ramus oblong, slightly widened distally, length about 3.45 times width, about 1.1 times as long as inner ramus, about 1.85 times length of peduncle, ventral and distal margins serrate, with many bundles of robust setae, dorsal margin weakly serrate, bearing several single robust setae; inner ramus situated dorsally on outer ramus, elliptical, length about 2.95 times width, medioproximal surface with small projection for receiving outer ramus, margins weakly serrate, ventral and lateral margins with several and many single robust setae, respectively, distal margin bearing bundle of robust setae. Telson about 1.15 times longer than wide, each medial margin bearing tiny notch in middle; each dorsal surface with 1 long and 1–2 short robust setae and 1 long and 1 short sensory setae, each lateral margin also bearing 1 long and 1 short sensory setae.

Variation. Gnathopod 2. Female, paratype, 6.6 mm (OMNH-Ar-11274, Fig. 5 View FIGURE 5 F-G2): symmetrical, coxa subtrapezoidal, other parts similar to smaller gnathopod 2 of male, holotype; medium-sized male, paratype, 5.6 mm (OMNH-Ar-11273): asymmetrical, similar to both gnathopods 2 of holotype, right propodus about 0.65 times as long as left propodus; small male, paratype, 4.3 mm (OMNH-Ar-11272): symmetrical, similar to smaller gnathopod 2 of holotype, but right propodus slightly shorter than left one. Pleonal epimera 1–3 ( Table 1 View TABLE 1 ), numbers of teeth and robust setae varying with body length. Urosomites 1–3, numbers of dorsal teeth same as those of holotype except for that on urosomite 1 of small male, 4.3 mm (OMNH-Ar-11272) ( Table 1 View TABLE 1 ). Telson . Female, 6.6 mm (OMNH-Ar- 11274), each lobe with 1 long and 2 short robust setae; smaller males, 5.6 and 4.3 mm (OMNH-Ar-11273, 11272), each lobe with 1 long and 1 short robust setae.

Coloration in recently fixed specimen ( Fig. 6 View FIGURE 6 ). Eyes light brown, anterior body faintly orangish white, posterior body white, sparsely with faintly red spots.

Remarks. The key in Krapp-Schickel & Vader (2009) does not lead these specimens to any species, because they have 9 dorsal teeth on the urosomite 1 whereas there are only “more than 10” and “six to eight” in the couplet 29 of the key. Ceradocus kiiensis sp. nov. has (1) asymmetrical male gnathopod 2, (2) larger male gnathopod 2 with oblique palm having single excavation and never having defining cusp, and (3) pleonites 1–3 with many dorsal teeth. These three characters are shared with several Ceradocus species. Several important characters of this new species and the related species having such characters are shown in Table 2 View TABLE 2 . All the related species are different from C. kiiensis in a part of the characters. For example, C. alama from Kuweit, C.? rubromaculatus sensu Lyons & Myers (1993) from Red Sea, and C. rubromaculatus sensu Monod (1937) from the Suez Canal (probably the same species) can be distinguished from C. kiiensis by the anterodistal projection on the basis of the larger male gnathopod 2. Ceradocus inermis from Japan, C. rubromaculatus sensu Ledoyer (1968) and C. tattersalli Ledoyer, 1983 both from Madagascar are different in the 0–1 posterior tooth each on the pleonal epimera 1–2. Ceradocus mizani from Malaysia and C. multidentatus from Vietnam have the deeper excavation on the palm of the larger male gnathopod 2 ( Lim et al. 2010, Dang & Le 2011). The most resembling species is C. rubromaculatus sensu Ren (1998, 2012 ) from the Nansha Islands, South China Sea; however, this species is distinguishable from C. kiiensis in the number of the dorsal teeth on the urosomite 1 and the number of the robust setae on the telson . In addition, plural species are probably mixed in C. rubromaculatus as Lyons & Myers (1993) stated, therefore, revision of the species complex is needed.