Quadrimaera setibasis, Ariyama, 2019

Ariyama, Hiroyuki, 2019, Species of the Maera - clade collected from Japan. Part 2: genera Austromaera Lowry & Springthorpe, 2005 and Quadrimaera Krapp-Schickel & Ruffo, 2000 (Crustacea: Amphipoda: Maeridae), Zootaxa 4554 (2), pp. 460-496 : 487-493

publication ID

https://doi.org/ 10.11646/zootaxa.4554.2.6

publication LSID

lsid:zoobank.org:pub:13B319F8-915A-4FE5-8E56-C8C61ECCF369

DOI

https://doi.org/10.5281/zenodo.5316966

persistent identifier

https://treatment.plazi.org/id/3611FE34-BA1A-4270-B6E3-78C1F9F1D047

taxon LSID

lsid:zoobank.org:act:3611FE34-BA1A-4270-B6E3-78C1F9F1D047

treatment provided by

Plazi

scientific name

Quadrimaera setibasis
status

sp. nov.

Quadrimaera setibasis View in CoL sp. nov.

[Japanese name: Taiheiyō-sunnariyokoebi-modoki, new]

( Figs 15H View FIGURE 15 1–2 View FIGURE 1 View FIGURE 2 , 21–25 View FIGURE 21 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 )

Type material. Holotype: male, 12.5 mm (OMNH-Ar-10615), Myojinzaki coast, Misaki Town , Osaka Prefecture, 34°18'55"N 135°05'39"E ( Fig. 1D View FIGURE 1 ), intertidal, under stones, 23 June 2013, coll. H. Ariyama. GoogleMaps Paratypes: 3 males, 5.2–9.2 mm (OMNH-Ar-10616–10618), 3 ovigerous females, 5.4–9.4 mm (OMNH-Ar-10619–10621) and female, 10.2 mm (OMNH-Ar-10622), same data as holotype GoogleMaps .

Type locality. Myojinzaki coast, Misaki Town, Osaka Prefecture in Japan .

Etymology. From the Latin seti (= setose) + basis, referring to the character of the pereopod 6.

Diagnosis. Gnathopod 1, coxa anteroventral corner rounded. Gnathopod 2, anterior margin of basis without robust setae, anterodistal corners of basis and ischium lobate on lateral and medial surfaces; propodus subrectangular, palm transverse, defined by large tooth, male palmar margin with small rounded excavation in middle and very small, V-shaped posterior excavation, female palmar margin with very shallow middle excavation, without posterior excavation. Pereopods 5–7, bases subovate, each posterodistal lobe small, posterior margin of pereopod 6 heavily setose. Uropod 3, outer ramus longer than inner ramus, about 1.3 times length of peduncle. Telson slightly wider than long, distal margins truncate, without inner distal teeth, each bearing 6 – 9 robust setae, longest seta about 75% length of telson.

Description. Based on holotype, male, 12.5 mm (OMNH-Ar-10615), and paratype, male, 9.2 mm (OMNH- Ar-10616) for uropod 3.

Head ( Figs 21–22 View FIGURE 21 View FIGURE 22 ). Anteroventral corner produced acutely, eyes oval, about 15% length of head. Antenna 1 about 0.45 times body length, densely setose; peduncle with ratio of lengths of articles 1–3 1:1.1:0.3, article 1 without posteromedial robust setae; accessory flagellum with 12 articles, terminal article minute, length about half of primary flagellum; primary flagellum with 33 articles, terminal article minute. Antenna 2 about 65% length of antenna 1, densely setose; peduncle with ratio of lengths of articles 3–5 1:3.9:3.0; flagellum with 13 articles, terminal article minute. Upper lip, dorsal margin produced, ventral margin rounded, with minute setae. Mandible, incisor bearing 3 cusps, lacinia mobilis 4-dentate, number of accessory setae 8 on left side and 9 on right side; palp article length ratio 1:1.6:1.6, articles 2 – 3 heavily setose. Lower lip with inner lobes, distal margins of inner and outer lobes bearing many short setae, mandibular processes small. Maxilla 1, inner plate bullet-shaped, with 3 long and 1 short apical setae, medial margin bare; distal margin of outer plate with 9 robust setae; palp article 1 bearing 2 long setae distolaterally, article 2 with many apical setae. Maxilla 2, outer plate larger than inner plate; medial margin of inner plate with several distal setae and many feeble setae. Maxilliped, distomedial corner of inner plate with 2 robust setae ventrally; outer plate with 19 long-to-short robust setae on distomedial margin; palp with 4 articles, article 2 densely setose medially, article 4 with large apical robust seta.

Pereon ( Fig. 23 View FIGURE 23 ). Gnathopod 1, coxa roundish trapezoidal, anteroventral corner rounded; basis bearing many long setae on posterior margin and medial surface; carpus with slight excavation on anterior margin; propodus palm defined by short robust seta, palmar margin lined with minute robust setae. Gnathopod 2, coxa subpentagonal; basis short, anterodistal corners on lateral and medial surfaces lobate, anterior margin without robust setae, posterior margin bearing several long setae; ischium, anterodistal corners on lateral and medial surfaces lobate; merus slightly produced posterodistally; propodus subrectangular, widened distally, length about 1.3 times width; palm transverse, defined by large tooth with robust seta, palmar margin with small rounded excavation in middle and very small V-shaped excavation posteriorly, anterior lobe with 4 lateral and 4 medial robust setae, posterior lobe bearing 9 lateral and 10 medial robust setae; dactylus, inner margin slightly swollen in middle.

Pereopods 3–4 subequal in shape, pereopod 3 about 1.1 times length of pereopod 4; coxae subrectangular; bases with 1–2 robust setae and 3–4 long setae on posterior margins. Pereopod 5 about 1.2 times length of pereopod 4; coxa with posterior lobe bearing robust seta; basis subovate, length about 1.4 times width, anterior margin with 3 short robust setae, posterior margin expanded in middle, bearing several short setae, posterodistal lobe small; merus, anterior margin setose. Pereopod 6, about 1.1 times length of pereopod 5; coxa with 2 and 1 ventral robust setae on anterior and posterior lobes, respectively; basis subovate, length about 1.55 times width, anterior and posterior margins almost parallel, posterodistal lobe small, anterior margin with several short robust setae, posterior margin heavily setose; merus, anterior margin densely setose. Pereopod 7 slightly shorter than pereopod 6; coxa subtrapezoidal, anteroventral corner with 2 robust setae; basis subovate, length about 1.45 times width, anterior and posterior margins almost parallel, posterodistal lobe small, anterior margin with several short robust setae, posterior margin bearing several short setae; merus, anterior margin heavily setose.

Pleon ( Fig. 24 View FIGURE 24 ). Epimera 1–3 slightly projected posteroventrally, each with minute seta posteriorly; ventral margins of epimera 1–3 with 2, 4, 8 robust setae, respectively. Pleopods 1–3, inner rami slightly longer than outer rami, inner ramus with 14, 13, 13 articles and outer rami with 15, 15, 14 articles respectively; pleopod 3 shortest, peduncle bearing several short setae and distal robust seta. Uropod 1, peduncle with 1 basofacial, 10 dorsolateral, 5 dorsomedial and 1 distolateral robust setae; outer ramus about 0.9 times length of inner ramus, about 75% length of peduncle, with 4 lateral, 5 medial and 5 terminal robust setae; inner ramus with 2 lateral, 5 medial and 5 terminal robust setae. Uropod 2 about 0.6 times length of uropod 1; peduncle bearing 3 dorsolateral and 2 dorsomedial robust setae; outer ramus about 85% length of inner ramus, about 1.15 times length of peduncle, with 5 dorsolateral, 5 dorsomedial (lost) and 5 (1 lost) terminal robust setae; inner ramus with 4 lateral, 5 medial and 5 terminal robust setae. Uropod 3, medial margin of peduncle bearing 2 groups of robust setae; outer ramus about 1.15 times length of inner ramus, about 1.3 times of peduncle length; outer ramus with 3 groups of robust setae laterally and single and 2 groups of robust setae medially, distal margin with minute second article and many long setae, longest distal seta about 0.7 times length of outer ramus; inner ramus with single lateral and 2+2 medial robust setae, distal margin bearing many long setae. Telson slightly wider than long, each lateral margin with 2 sensory setae; distal margins truncate, without inner distal teeth, each bearing 6–7 long and 1–2 short robust setae, longest robust seta about 75% of telson length.

Variation. Gnathopod 2. Female, 10.2 mm (OMNH-Ar-10622, Fig. 24 View FIGURE 24 F-G2), middle excavation on palm very shallow, posterior excavation absent, anterior lobe with 4 lateral and 5 medial robust setae, posterior lobe bearing 8 lateral and 7 medial robust setae. Male, 9.2 mm (OMNH-Ar-10616, Fig. 24 View FIGURE 24 M-G2) almost same as that of holotype, male, anterior lobe with 5 lateral and 3 medial robust setae, posterior lobe bearing 9 lateral and 8 medial robust setae. Small male, 5.2 mm (OMNH-Ar-10618, Fig. 24 View FIGURE 24 SM-G2), middle excavation on palm indistinct, palmar margin with 10 lateral and 10 medial robust setae. Uropod 3. Small male, 5.2 mm (OMNH-Ar-10618), rami slender, outer ramus about 1.8 times length of peduncle. Small ovigerous female, 5.4 mm (OMNH-Ar-10621), rami slender, outer ramus about 1.9 times length of peduncle. Telson. Male, 9.2 mm (OMNH-Ar-10616, Fig. 24 View FIGURE 24 M-G2), distal margin of each lobe bearing 5 – 6 long and single short robust setae.

Coloration in life ( Fig. 25 View FIGURE 25 ). Eyes dark red, antennae pale pink, gnathopod 2 propodus white, dactylus pale orange, other parts bluish light green.

Remarks. Only two species of Quadrimaera , this new species and Q. schellenbergi from Red Sea (Krapp- Schickel & Ruffo 2006), have the heavily setose basis of the pereopod 6. Quadrimaera setibasis sp. nov. is different from Q. schellenbergi in the narrower anterior lobe of the male gnathopod 2 palm and the non-setose bases of the pereopods 5 and 7 ( Ruffo 1938, Krapp-Schickel & Ruffo 2006). In addition, this species is the largest in the genus Quadrimaera (maximum body length: 12.5 mm in male).

Habitat. Under stones, intertidal. This species sometimes occurs together with Orientomaera decipiens Ariyama, 2018 and O. obliquua Ariyama, 2018 .

Distribution. Japan: Misaki Town in Osaka Prefecture (present study).

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Amphipoda

Family

Maeridae

Genus

Quadrimaera

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