Quadrimaera pacifica ( Schellenberg, 1938 )

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 : 474-481

Quadrimaera pacifica ( Schellenberg, 1938)

[Japanese name: Taiheiyō-sunnariyokoebi, new] ( Figs 10–14 , 15A 1–3 )

Maera pacifica Schellenberg, 1938: 42 , figs 19–20.— J.L. Barnard, 1965: 511.— Sivaprakasam, 1968: 101.— Sivaprakasam, 1970: 35.— J.L. Barnard, 1970: 150, figs 92–93.— J.L. Barnard, 1971: 84, figs 31, 38, 40–41.— Surya Rao, 1972: 196.— Ledoyer, 1972: 227, fig. 43 (forme A).— Ortiz, 1978: 8 (list).— Ledoyer, 1978: 278.— Ledoyer, 1979: 80.— Ledoyer, 1982: 534, figs 201–202 (forme A).— Ledoyer, 1984: 69 (forme A).— Myers, 1986a: 1389.— Myers, 1986b: 287 (list).— Kim & Kim, 1987: 11, fig. 10.— Myers, 1989: 66 (list).— Myers, 1990: 156 (list).— Kim & Kim, 1991: 329.— Myers, 1995: 38 (list).— Krapp, Marti & Ruffo, 1996: 48 (list).— Ren & Zheng, 1996: 64, fig. 6.— Myers, 1997: 109 (list).— Appadoo & Steele, 1998: 639 (list).— Ortiz & Lalana, 1999: 195 (list).— Ruffo, Krapp & Gable, 2000: 13, figs 3, 5d.— Varela, Ortiz & Lalana, 2003: 74 (list).— Ren, 2012: 247, fig.108.

Quadrimaera pacifica .— Krapp-Schickel & Ruffo, 2000: 196, figs 1–2 (as “prope”).—Krapp-Schickel, 2000: 417 (list, key).— Appadoo, Myers & Fagoonee, 2002: 650, fig. 5 (as “cf.”).— Krapp-Schickel, 2008: 25 (list). — Krapp-Schickel, 2009: 627 , fig. 20.— Milne & Griffiths, 2013: 73.— Paz-Ríos, Simões & Ardisson, 2013: 7, fig. 6 (as “prope”).— Hughes, 2015b: 241 .— Myers, 2016: 467 , fig. 15.

not Maera pacifica .— Nayar, 1959: 23, pl. 7, figs 16–17.— Ruffo, 1969: 26.— Ledoyer, 1972: 229, fig. 44 (forme B).— Griffiths, 1976: 25, fig. 8.— Ledoyer, 1982: 536, fig. 203 (forme B).— Myers, 1985: 112, figs 89–90. [according to Ruffo, Krapp & Gable (2000)]

Material examined. Four males, 5.9–8.5 mm (OMNH-Ar-10599–10602), ovigerous female, 7.4 mm (OMNH-Ar- 10603) and female, 6.2 mm (OMNH-Ar-10604), Ariake Sea, northeast of Amakusa-shimoshima Island in Nagasaki Prefecture, 32°32'46"N 130°11'23"E ( Fig. 1H ), shell and stone bottom, using dredge, 4 April 2006, coll. K. Mori; male, 8.6 mm (OMNH-Ar-10605), Akahama, Otsuchi Town, Iwate Prefecture, 39°21'00"N 141°56'09"E ( Fig. 1A ), 1–5 m depth, among a brown alga Sargassum yezoense , using SCUBA, 27 October 2015, coll. M. Kodama; ovigerous female, 7.6 mm (OMNH-Ar-10606), same locality and habitat, 15 July 2015, coll. M. Kodama; male, 8.7 mm (OMNH-Ar-10607) and female, 7.4 mm (OMNH-Ar-10608), Bakuchi Cape, Maizuru City, Kyoto Prefecture, 35°33'07"N 135°20'35"E ( Fig. 1C ), subtidal, phytal, 22 April, 1979, coll. H. Ariyama; male, 6.5 mm (OMNH-Ar-10609) and female, 6.3 mm (OMNH-Ar-10610), Tagurazaki coast, Wakayama City, Wakayama Prefecture, 34°16'02"N 135°03'39"E ( Fig. 1D ), intertidal, under stones, 6 May 2001, coll. H. Ariyama; male, 6.7 mm (OMNH-Ar-10611) and ovigerous female, 7.1 mm (OMNH-Ar-10612), Izumozaki coast, Kushimoto Town, Wakayama Prefecture, 33°26'46"N 135°47'42"E ( Fig. 1E ), 3 m depth, among holdfast of a brown alga Eckloniopsis radicosa , 8 August 2009, coll. H. Ariyama; male, 5.7 mm (OMNH-Ar-10613) and female, 5.4 mm (OMNH-Ar- 10614), mouth of Koajiro Bay, Miura City, Kanagawa Prefecture ( Fig. 1B ), 4–5 m depth, among coralline algae, using SCUBA, 19 September 2014, coll. H. Kohtsuka.

Type locality. Makin, Gilbert Islands in Kiribati ( Schellenberg 1938, Appadoo et al. 2002).

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, posterior excavation present or absent, female palmar margin with indistinct excavation in middle, without posterior excavation. Pereopods 5–7, bases ovate, each posterodistal lobe developed, posterior margins not setose. Uropod 3, outer ramus slightly longer than inner ramus, usually about 1.4 times length of peduncle. Telson wider than long, distal margins truncate, each lobe with or without inner distal tooth, bearing usually 5 robust setae, longest seta almost same length as telson.

Description. Based on male, 8.5 mm (OMNH-Ar-10599), and male, 7.5 mm (OMNH-Ar-10600) for pereopod 6.

Head ( Figs 10–11 ). Anteroventral corner produced acutely, eyes subrounded, about quarter length of head. Antenna 1 about 0.45 times body length, setose; peduncle with ratio of lengths of articles 1–3 1:1.15:0.3, article 1 with 5 robust setae posteromedially, anterodistal corner with bundle of setae; accessory flagellum with 11 articles, terminal article minute, length about half of primary flagellum; primary flagellum with 25 articles. Antenna 2 about 65% length of antenna 1, setose; peduncle with ratio of lengths of articles 3–5 1:3.9:3.2; flagellum with 10 articles, terminal article minute. Upper lip, ventral margin rounded, with short setae. Mandible, incisor bearing 4 cusps, left lacinia mobilis 4-dentate, right lacinia mobilis 6-dentate, number of accessory setae 5 on both sides; palp article length ratio 1:1.6:2.0, articles 2 – 3 heavily setose. Lower lip with inner lobes, distal margins of inner and outer lobes setose, mandibular processes small. Maxilla 1, inner plate longish oval, with 3 long and 2 tiny apical setae, medial margin with several feeble setae; distal margin of outer plate with 9 robust setae; palp article 1 bearing long seta distolaterally, article 2 with many apical setae. Maxilla 2, outer plate larger than inner plate; medial margin of inner plate with many feeble setae. Maxilliped, distomedial corner of inner plate with 2 robust setae ventrally; outer plate with 17 long-to-short robust setae on distomedial margin; palp with 4 articles, article 4 with large apical robust seta.

Pereon ( Fig. 12 ). 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. Gnathopod 2, coxa subtrapezoidal; basis short, anterodistal corners on lateral and medial surfaces lobate, anterior margin without robust setae, posterior margin bearing 2 long setae; ischium, anterodistal corners on lateral and medial surfaces lobate; merus produced posterodistally; propodus subrectangular, slightly widened distally, length about 1.2 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 6 lateral and 3 medial robust setae, posterior lobe bearing 7 lateral and 5 medial robust setae; dactylus, inner margin slightly swollen in middle.

Pereopods 3–4 subequal in shape, pereopod 3 about 115% length of pereopod 4; coxae subrectangular; bases without long setae. Pereopod 5 about 1.1 times length of pereopod 4; coxa with posterior lobe bearing robust seta; basis ovate, length about 1.2 times width, anterior margin with 3 short robust setae. Pereopod 6, coxa with ventral robust seta each on anterior and posterior lobes; basis ovate, length about 1.3 times width, anterior margin with 4 short robust setae, posterior margin with sparse short setae. Pereopod 7 about 1.1 times length of pereopod 5; coxa subtrapezoidal, anteroventral corner with robust seta; basis ovate, length about 1.3 times width, posterodistal lobe large, anterior margin with 5 short robust setae, posterior margin smooth.

Pleon ( Fig. 13 ). Epimera 1–3 slightly projected posteroventrally, each with minute seta posteriorly; epimeron 2 with oblique lateral ridge, ventral margins of epimera 1–3 with 3, 5, 7 robust setae, respectively. Pleopods 1–3, inner rami slightly longer than outer rami, each inner ramus with 10 articles and outer rami with 13, 13, 11 articles respectively; pleopod 3 shortest, peduncle bearing 4 short setae and distal robust seta. Uropod 1, peduncle with 1 basofacial, 11 dorsolateral, 5 dorsomedial and 1 distolateral robust setae; outer ramus about 85% length of inner ramus, about 0.6 times length of peduncle, with 3 (1 lost) lateral, 5 medial and 5 terminal robust setae; inner ramus with 5 lateral, 5 medial and 5 (1 lost) terminal robust setae. Uropod 2 about 65% length of uropod 1; peduncle bearing 3 dorsolateral and 3 dorsomedial robust setae; outer ramus about 0.8 times length of inner ramus, slightly longer than peduncle, with 4 lateral, 3 medial and 5 terminal robust setae; inner ramus with 3 lateral, 4 medial and 5 terminal robust setae. Uropod 3 about 65% length of uropod 2; distolateral and distomedial corners of peduncle with 1 and 3 robust setae, respectively; rami short, about 1.3 times length of peduncle, outer ramus slightly longer than inner ramus; outer ramus with single and 2 groups of robust setae laterally and 1+2 robust setae medially, distal margin with minute second article and many long setae, longest distal seta about 0.8 times length of outer ramus; inner ramus with 1 and 2 robust setae on lateral and medial margins, respectively, distal margin bearing many long setae. Telson wider than long, distal margins truncate, inner distal corners each with short tooth; each lateral margin with 2 sensory setae, each distal margin bearing 4–5 long robust setae and sensory seta, longest robust seta almost same as telson length.

Variation. Gnathopod 2. Ovigerous female, 7.4 mm (OMNH-Ar-10603, Fig. 13 F-G2): middle excavation on palm indistinct, posterior excavation absent, palmer margin with 13 lateral and 11 medial robust setae. Male, 6.7 mm (OMNH-Ar-10611, Fig. 13M 2-G2 ): posterior excavation on palm distinct, U-shaped, anterior lobe of palmer margin with 5 lateral and 5 medial robust setae, posterior lobe bearing 7 lateral and 6 medial robust setae [almost same in 2 males, 6.5 and 5.7 mm (OMNH-Ar-10609, 10613)]. Small male, 5.9 mm (OMNH-Ar-10602, Fig. 13 SM- G2): middle excavation on palm present but smaller than large male, posterior excavation absent, anterior lobe of palmer margin with 4 lateral and 4 medial robust setae, posterior lobe bearing 10 lateral and 4 medial robust setae. Uropod 3. Male, 8.7 mm (OMNH-Ar-10607): rami slender, outer ramus about 1.45 times length of peduncle. Male, 5.9 mm (OMNH-Ar-10602): outer ramus about 1.5 times length of peduncle. Telson. Male, 7.5 mm (OMNH-Ar- 10600, Fig.13M 1-T ), inner distal teeth indistinct, distal margins of lobes each bearing 3 long and 2 short robust setae [almost same in male, 6.5 mm (OMNH-Ar-10609) and 2 females, 7.4 and 5.4 mm (OMNH-Ar-10603, 10614)].

Coloration in frozen-thawed specimen ( Fig. 14 ). Eyes black, other parts purplish light gray.

Remarks. The present specimens of Quadrimaera pacifica have the characteristic transverse palm of the male gnathopod 2. Its margin has (1) large posterodistal tooth, (2) small rounded excavation in middle (width of excavation 0.1–0.2 times of palm width), (3) anterior lobe narrower and produced more distally than posterior lobe, (4) posterodistal corner of anterior lobe projected, and (5) anterodistal corner of posterior lobe not projected. Such a palm is shared with Q. pacfica hitherto recorded from various localities [except for Maera pacifica sensu Nayar (1959) having wider anterior lobe than posterior lobe, see above synonym list], Q. ceres , Q. rocasensis , Q. setibasis sp. nov. and Q. vallaris . However, Q. pacifica can be distinguished from Q. ceres , Q. rocasensis and Q. vallaris by the strongly expanded basis of the pereopod 7 (length/width: about 1.3 in Q. pacifica [except Paz-Ríos et al. (2013)] but about 1.5 in the latter 3 species), and from Q. setibasis sp. nov. by the non-setose basis of the pereopod 6.

There are some variable characters in the Japanese specimens: the uropod 3 rami are sometimes elongated, the distal end of the telson sometimes lacks the inner distal teeth ( Fig.13M 1-T ), and especially the posterior excavation on the male gnathopod 2 palm varies from absent to distinct. In most of the large specimens, the excavation is very small and V-shaped ( Figs 12G 2 , 15A 1 ), but sometimes is larger and U-shaped ( Figs 13M 2-G2 , 15A 2 ). Such a variety seems to be similar in foreign specimens of the species including the original description ( Schellenberg 1938). Hawaiian and Chinese specimens have the elongated rami of the uropod 3 ( J.L. Barnard 1970, Ren 2012). The distal shape of the telson is variable (ex. J.L. Barnard 1970). The gnathopod 2 palms of Q. pacifica in various localities and the resemble species as mentioned above are shown in Fig. 15 . This figure suggests that the palms of Q. pacifica vary greatly in the posterior excavation and the posterodistal tooth, and that the palms of the five species relatively resemble one another. Because this species has not only large morphological variation but also very wide distribution (see “Distribution”), there is a possibility that several species are mixed in a single species. Therefore, it is expected that Q. pacifica in each locality and the resemble species are reexamined closer in consideration of the change with growth.

Habitat in Japan. Under stones, intertidal; among algae, 1–5 m depth; shell and stone bottom, subtidal. This species often occurs together with Orientomaera brevispina ( Kim & Kim, 1991) and sometimes with O. rotundicoxa Ariyama, 2018 .

Distribution. Pacific Ocean (including marginal seas). Japan: Iwate, Kyoto, Kanagawa, Osaka and Wakayama Prefectures, Ariake Sea (present study); Korea: Cheju Island ( Kim & Kim 1987), Ulreung Island ( Kim & Kim 1991); China: Hong Kong ( Ren & Zheng 1996, Ren 2012), Hainan Island ( Ren 2012); Nansha Islands ( Ren 2012); Indonesia: Pari Island ( Ortiz & Lalana 1999); Micronesia: Caroline Islands ( J.L. Barnard 1965, Myers 1995), Marshall Islands ( J.L. Barnard 1965), Palau ( Myers 2016), Gilbert Islands ( Schellenberg 1938); Melanesia: Fiji ( Schellenberg 1938), New Caledonia ( Ledoyer 1984); Polynesia: Hawaii ( Schellenberg 1938, J.L. Barnard 1970), Western Samoa ( Myers 1997), Niue ( Myers 1986a), Cook Islands ( Myers 1990), Society Islands ( Myers 1989), Tonga ( Myers 1986b), Kermadec Islands ( Hughes 2015b); Australia: Great Barrier Reef ( Krapp-Schickel 2009), Torres Strait, One Tree Island ( Hughes 2015b). Indian Ocean. India: Palk Bay ( Sivaprakasam 1968), Gulf of Manner ( Sivaprakasam 1970), Bay of Bengal ( Surya Rao 1972); Mauritius ( Ledoyer 1978, Appadoo & Steele 1998, Appadoo et al. 2002); Madagascar ( Ledoyer 1972, 1979, 1982); South Africa ( Milne & Griffiths 2013). Gulf of Mexico and Caribbean Sea. Mexico: Alacranes Reef ( Paz-Ríos et al. 2013), Mujeres Island ( Krapp-Schickel & Ruffo 2000); Cuba ( Ortiz 1978, Ruffo et al. 2000, Varela et al. 2003); Cayman Islands, St. Barthélemy, Tobago Island ( Krapp-Schickel & Ruffo 2000); Venezuela: Margarita Island, Centinela ( Krapp-Schickel & Ruffo 2000).

Figures

FIGURE 1. Map showing collecting sites of the examined specimens. A, Otsuchi Town in Iwate Prefecture; B, Miura City in Kanagawa Prefecture; C, Maizuru City in Kyoto Prefecture; D, Misaki Town in Osaka Prefecture and Wakayama City in Wakayama Prefecture; E, Kushimoto Town in Wakayama Prefecture; F–H, Ariake Sea; I, Nakadōri Island in the Gotō Islands, Nagasaki Prefecture; J, south of Yakushima Island in Kagoshima Prefecture.

FIGURE 2. Austromaera ariakensis sp. nov. Paratype, ovigerous female, 10.2 mm (OMNH-Ar-10594). Habitus.

FIGURE 3. Austromaera ariakensis sp. nov. Holotype, male, 10.3 mm (OMNH-Ar-10591). Scales: 0.15 mm.

FIGURE 10. Quadrimaera pacifica (Schellenberg, 1938). Male, 8.5 mm (OMNH-Ar-10599). Habitus. Outer ramus of uropod 2 lost.

FIGURE 11. Quadrimaera pacifica (Schellenberg, 1938). Male, 8.5 mm (OMNH-Ar-10599). Scales: 0.1 mm.

FIGURE 12. Quadrimaera pacifica (Schellenberg, 1938). All except for M, male, 8.5 mm (OMNH-Ar-10599); M, male, 7.5 mm (OMNH-Ar-10600). Scales: 0.2 mm.

FIGURE 13. Quadrimaera pacifica (Schellenberg, 1938). All except for F, M1, M2 and SM, male, 8.5 mm (OMNH-Ar- 10599); F, ovigerous female, 7.4 mm (OMNH-Ar-10603); M1, male, 7.5 mm (OMNH-Ar-10600); M2, male, 6.7 mm (OMNH- Ar-10611); SM, male, 5.9 mm (OMNH-Ar-10602). Scales: 0.1 mm.

FIGURE 14. Quadrimaera pacifica (Schellenberg, 1938). Male, 8.6 mm (OMNH-Ar-10605). Frozen-thawed specimen, photograph by M. Kodama.

FIGURE 15. Comparison of gnathopod 2 palm. Quadrimaera pacifica (Schellenberg, 1938). A1, male, 8.5 mm (OMNH-Ar- 10599), Ariake Sea; A2, male, 6.7 mm (OMNH-Ar-10611), Kushimoto Town; A3, ovigerous female, 7.4 mm (OMNH-Ar- 10603), Ariake Sea; B1, male, 5.0 mm, and B2, female, 5.7 mm, Hawaii [copy of Fig. 92 in J.L. Barnard (1970)]; C1, male, 6 mm, and C2, female, 5.5 mm, Gilbert Islands [copy of Fig. 19 in Schellenberg (1938)]; D1, male, 7 mm, and D2, female, 5? mm, Madagascar [copy of Fig. 201 in Ledoyer (1982)]; E1, male, 4.5 mm, and E2, ovigerous female, 4.2 mm, Cayman Islands [copy of Fig. 1 in Krapp-Schickel & Ruffo (2000)]. Quadrimaera ceres (Ruffo, Krapp & Gable, 2000). F1, male, 6 mm and F2, ovigerous female, 5 mm, Bermuda [copy of Fig. 5 in Ruffo et al. (2000)]. Quadrimaera rocasensis Senna & Serejo, 2007. G1, male, 6.3 mm, Brazil [copy of Fig. 6 in Senna & Serejo (2007)]. Quadrimaera setibasis sp. nov. H1, male, 9.2 mm (OMNH- Ar-10616), and H2, female, 10.2 mm (OMNH-Ar-10622), Misaki Town. Quadrimaera vallaris Hughes, 2015b. I1, male, 4.0 mm, Nepean Island [copy of Fig. 45 in Hughes (2015b)].