Protohyale (Boreohyale) triangulata ( Hiwatari, 2003 )

Jung, Tae Won & Yoon, Seong Myeong, 2013, New Record of a Hyalid Species, Protohyale (Boreohyale) triangulata (Crustacea: Amphipoda: Hyalidae), from Korea, Anim. Syst. Evol. Divers 29, No. 2, pp. 198-205 : 199-202

1 * Protohyale (Boreohyale) triangulata ( Hiwatari, 2003)

( Figs. 1 - 4 )

Hyale triangulata Hiwatari, 2003: 245 - 249 , figs. 10, 11.

Hyale schmidti: Iwasa, 1939: 278 - 280 , Pl. 17, fig. 17 [not Heller, 1866].

Hyale rubra: Kim and Kim, 1987: 16 - 17 , fig. 14 [not Thom-son, 1879].

Material examined. Korea: 17♂♂ 21♀♀, Jeollanam-do: Wando-gun, Soan-myeon, Bija-ri , 12 May 2010, Jung TW ; 1♂ 1♀, Wando-gun, Chungsan-myeon, Sinheung-ri , 9 Jun 2010, Jung TW ; 2♂♂ 2♀♀, Chungcheongnam-do: Seo-cheon-gun, Seo-myeon, Chunjangdae beach, Dodun-ri , 24 Sep 2009, Kim JG .

Description. Male: Body medium, stout, about 10.2 mm long.

Head ( Fig. 1A ), rostrum short, minute; anterior cephalic lobe obliquely truncated, apex slightly concave; eyes circular, medium in size. Posterodistal margin of pleonal epimera 1 rounded, and epimera 2 - 3 subacute ( Fig. 3I ).

Antenna 1 ( Fig. 1A ) about half of antenna 2, tip of flagel-lum over the peduncle 5 of antenna 2; length ratio of pedun-cle 1 - 3 1: 0.70: 0.58, article 1 with a pair of penicillate setae anteromedially; flagellum short, composed of more than 12 segments, each segment with 1 or 2 aesthetascs, but distal 2 segments not bearing.

Antenna 2 ( Fig. 1A ) not reaching half of body length; gland cone produced, with a spine apically; peduncle 3, distal mar-gin truncated obliquely; peduncle 5 subequal to peduncle 3 and 4 combined in length; flagellum long, composed of 28 segments.

Upper lip ( Fig. 1C ). Apical margin rounded with short bris-tles.

Lower lip ( Fig. 1B ) ordinary, inner lobe indistinct; outer lobe, apical margin rounded, with short bristles; mandibular processes developed.

Left mandible ( Fig. 1D ). Incisor 7-toothed; lacinia mobilis 5-toothed; 3 pectinate accessory blades; molar process well developed with one plumose seta.

Right mandible ( Fig. 1E, F ). Incisor 6 and 1/2-toothed; lacinia mobilis tricuspate consisting of 2 pectinate and 1 blunt teeth; 2 pectinate accessory blades; molar well developed with one plumose seta.

Maxilla 1 ( Fig. 1H ). Inner plate gradually slendered distal-ly, with 2 plumose apical setae; outer plate with 9 toothed spines distally; palp 1-articulate, with 2 different apical setae in length.

Maxilla 2 ( Fig. 1G ). Inner plate, apical margin obliquely rounded, with two row composed of pectinate and simple setae, respectively, inner distal corner with a long pectinate seta; outer plate, apical setae longer than that of inner plate.

Maxilliped ( Fig. 1I ). Inner plate with 3 stout apical spines and several plumose setae near the inner and apical margins; outer plate, apical margin rounded, spatulate, reaching mid-dle of segment 2 of palp, with a row of several plumose setae apically; palp composed of 4 segments, distal margin of seg-ment 1 oblique, inner margin of segment 2 and 3 slightly sinuate with numerous setae, segment 3 with 2 rows compos-ed of several pectinate setae near the distal margin, segment 4 falcate, surface and inner margin pectinate, inner margin with several short and long setae beyond the tip of apical spine, apical spine elongate.

Gnathopod 1 ( Fig. 2A ). Coxa broad, slightly extended for-ward, posterior cusp lacking; basis trapezoidal, posterior mar-gin with 2 medial setae; ischium, anterior lobe weak; merus subrectangular, slightly extended posterodistally; carpus, anterior margin rounded, with 5 pectinate setae, carpal lobe developed but lacking serration, with a row composed of sev-eral pectinate setae; propodus triangular in shape, postero-proximal corner subquadrate, palm and posterior margin not clear, but bearing a defining spine, palmer margin lined with fine and normal setae; dactylus falcate.

Gnathopod 2 ( Fig. 2B ). Coxa subquadrate, anterior and ventral margin convex, posterior cusp weak; basis broadly lobate anterodistally, posterior margin with 4 setae; ischium with a hemicircular anterior lobe; merus, posterodistal corner produced distally; carpus with a small hemicircular lobe ven-trally, and anterodistal corner with a stout spine; propodus large, subovate, anterior margin convex, with 2 spines, palm defined by inner and outer spines, slightly shorter than poste-rior margin, lined with stout spines and short setae at inner and outer margin, proximal margin of palm with a weak hump; dactylus fitting palm.

Korean name: 1 *세모손해±숨ḋẚ새ae

Pereopod 3 ( Fig. 2C ). Coxa subquadrate, ventral margin convex; basis slendered, slightly trapezoidal, anterior lobe weak, with a plumose seta distally, posterior margin with 4 pairs of a short and a long seta, and 4 pectinate distal setae; ischium, anterior lobe weak; merus, anterior margin expand-ed anteriorly, with 3 spines and produced distally, anterodis-tal corner with a pectinate and a simple seta; carpus shorter than merus, slightly extended distally, with a stout spine at posterodistal corner; propodus slender, anterior margin unarmed, posterior margin with 4 spines and a distal locking spine; dactylus curved.

Pereopod 4 ( Fig. 2D ) similar in size and shape with pereo-pod 3 except for larger coxa with bisinuate posterodoral ex-cavation.

Pereopod 5 ( Fig. 2E ). Coxa bilobate, posterior lobe slight-ly dilated posterodistally; basis, anterior margin with 5 long setae proximally and lined with several single spines, distal corner with a large and a small spine, posterior margin broad-ly expanded, subcircular, weakly crenulated, lined with mi-nute setae, with a notch medially bearing a penicillate seta; ischium subquadrate, with a weak posterior lobe; merus, an-terior margin with 1 and 3 medial spines in turn, distal corner with 5 spines, posterior margin expanded posterodistally, with 2 medial spines, posterodistal corner with 4 stout spines; carpus gradually extending distally, each antero- and pos-terodistal corner with a group composed of 6 and 3 spines, respectively; propodus slender, anterior margin with 4 spines and a distal locking spine, posterior margin unarmed; dacty-lus falcate.

Pereopod 6 ( Fig. 3A, B ) larger than pereopod 5; coxa bilobate, anterior lobe small; basis, anterior margin slightly convex, with 3 small spines proximally, and lined with 1 and 3 pairs of small spines, distal corner with a pair of spines, posterior margin broadly expanded, but not subcircular, slightly flattened, lined with minute setae, 1/3 proximal margin with a notch bearing a penicillate seta; ischium subquadrate, with a posterior lobe; merus, posterior margin drastically expand-ed posterodistally, with 3 spines, distal corner produced distally with a group of 4 spines, anterior margin with a pair of medial spines, distal corner with a group of 3 spines; carpus gradually extending posterodistally, anteromedial margin with a pair of spines, each antero- and posterodistal corner with a group of 5 and 4 spines, respectively; propodus, ante-rior margin with 4 spines and a distal locking spine, posterior margin unarmed; dactylus falcate.

Pereopod 7 ( Fig. 3C, D ). Coxa unilobate, ventral margin rounded, posteroventral corner weakly crenulated, with mi-nute setae; basis, anterior margin slightly convex, lined with 5 pairs of small spines, distal corner with a pair of spines, posterior margin broadly expanded, slightly dilated postero-distally, weakly crenulated, lined with minute setae, with a medial notch that bearing a penicillate seta; other segments similar to that of pereopod 6 in shape.

Uropod 1 ( Fig. 3E ). Peduncle with a large distolateral spine and 2 inner and 3 outer dorsolateral spines; inner and outer rami subequal in length, inner ramus with 3 dorsolateral spine, 2 pairs of apicomost spines and a stout apical spine, outer ramus with 2 dorsolateral spines, 3 apicomost spines and a stout apical spine.

Uropod 2 ( Fig. 3F ). Peduncle stout but short, 1 inner and 2 outer lateral spines; inner ramus longer than outer ramus, with 2 dorsal spines, a pairs of apicomost spines, and a stout apical spine, outer rami with 2 dorsolateral spines, 3 apicomost spines and a stout apical spine.

Uropod 3 ( Fig. 3G ) uniramus; peduncle twice length of ramus, with 2 apicodorsal spines; ramus with 4 apical spines.

Telson ( Fig. 3H ) cleft completely; each lobe subtriangular. Female: Gnathopod 1 ( Fig. 4G ). Basis slightly trapezoidal in form, anterior lobe present but not developed, with a minute seta at distal corner; ischum subquadrate, anterior lobe weak; posterodistal margin of merus slightly pointed; carpus lobe shallow, lacking serration, lined with 7 pectinate setae; pro-podus slender, subrectangular, middle of posterior margin slightly concave with 3 setae, palm oblique, defined by 2 spines; dactylus fitting palm.

Gnathopod 2 ( Fig. 4H ) similar to gnathopod 1 but larger.

Oostegite of gnathopod 2 subtriangular; oostegites of pere-opod 3 and 4 elongate oval, and that of pereopod 5 roundish triangular in shape ( Fig. 4I - L ).

Distribution. Korea, Japan.

Remarks. Bousfield and Hendrycks (2002) suggested that the preamplexing notch of pereon segment 2 of matured females is generic or subgeneric, and constituted specific character states of reproductive morphology in the family Hyalidae . According to them, a newly recorded Korean spec-ies, P. triangulata , belongs to the Protohyale (Boreohyale) group in the shape of the preamplexing notch ( Bousfield and Hendrycks, 2002). As a Korean hyalid species, Hyale rubra (Thomson, 1987) was reported by Kim and Kim (1987), based on the specimens collected from Cheju Island and its adjacent waters. They synomized Iwasa’s Japanese materials of H. schmidti as H. rubra based on Barnard’s (1970) iden-tification, and they mentioned that Korean and Japanese materials regarded as H. rubra showed some differences, and possible status of them as subspecies of H. rubra ( Kim and Kim, 1987) . Recently, Hiwatari (2003) reviewed the Japanese hyalid species, and revised Iwasa’s Hyale schmidti as a new species, Hyale triangulata Hiwatari, 2003 . According to this, the previous report of H. rubra in Korea ( Kim and Kim, 1987) was that of H. triangulata , and is now revised as that of Protohyale (Boreohyale) triangulata ( Hiwatari, 2003) . Mor-pological characteristics of Korean specimens of P. (B.) tri-angulata in the present study agree well with Hiwatari’s ori-gnal description ( Hiwatari, 2003), especially the triangular shape of the propodus of ganthopod 1 in matured males. But compared with Japanese, Korean specimens have several minor differences in the number of teeth of the incisor of the right mandible, in having several pectinated setae of gnath-opods and pereopods, and in the absence of setae on the inner margin of the peduncle of uropod 3 and the lateral margin of telson. These seem to be variations, but the real meanings of them are in need of further study.

Figures

Fig. 1. Protohyale (Boreohyale) triangulata (Hiwatari, 2003), male. A, Head, antenna 1 and antenna 2; B, Lower lip; C, Upper lip; D, Left mandible; E, Right mandible; F, Lacina mobilis of right mandible; G, Maxilla 2; H, Maxilla 1; I, Maxilliped. Scale bars: A, F=0.5 mm, B-E, G-I=0.25 mm.

Fig. 2. Protohyale (Boreohyale) triangulata (Hiwatari, 2003), male. A, Gnathopod 1; B, Gnathopod 2; C, Pereopod 3; D, Pereopod 4; E, Pereopod 5. Scale bars: A-E=0.5 mm.

Fig. 3. Protohyale (Boreohyale) triangulata (Hiwatari, 2003), male. A, Pereopod 6; B, Notch and surge seta of pereopod 6; C, Pereopod 7; D, Notch and surge seta of pereopod 7; E, Uropod 1; F, Uropod 2; G, Uropod 3; H, Telson; I, Pleonal epimera. Scale bars: A, C, E-I=0.5 mm, B, D=0.2 mm.

Fig. 4. Protohyale (Boreohyale) triangulata (Hiwatari, 2003), male (A-E) and female (F-L). A-E, Coxal gills on gnathopod 2- pereopod 6; F, Preamplexing notch; G, Gnathopod 1; H, Gnathopod 2; I, Oostegite on gnathopod 2; J-L, Oostegites on pereopod 3-5. Scale bars: A-F, I-L=0.5 mm, G, H=0.2 mm.