Protohyale pumila ( Hiwatari and Kajihara, 1981 )

Myung-Hwa Shin, Won Kim, 2012, First Record of a Hyalid Species, Protohyale pumila (Crustacea: Amphipoda: Hyalidae), from Korea, Anim. Syst. Evol. Divers 28 (4), pp. 312-316 : 312-316

1 * Protohyale pumila ( Hiwatari and Kajihara, 1981) ( Figs. 1 - 3 )

Hyale dollfusi: Iwasa, 1939: 280 , Pl. 18, text-fig. 18; Steph-ensen, 1944: 69, fig. 24 [not Chevreux, 1911].

Korean name: 1 *꼬마Njnj해±숨ḍǟ새Ạ

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Hyale pumila Hiwatari and Kajihara, 1981: 35 , figs. 1 - 4. Protohyale (Boreohyale) pumila: Bousfield and Hendrycks, 2002 : 77, fig. 36.

Material examined. Korea: 216♂♂, 21♀♀, Jeju-do, Jo-cheon-eup, Hamdeog-ri, Hamdeog Beach , 29 May 2007 .

Description. Male: Body ( Fig. 1 ) 6.98 mm long, compressed. Lateral cephalic lobe slightly convex, anteroventral cephalic excavation shallow. Eye black, large. Terminal part of anten-na 1 reaching about one - fourth portion of antenna 2 flagel-lum. Antenna 2 about 0.5 times as long as body length, pe-duncle 5 slightly longer than peduncle 4. Palp article 4 of maxilliped slightly broad, bearing short apical spine and short marginal setae.

Coxa of gnathopod 1 ( Fig. 2A ) broad; basis without ante-rodistal lobe; carpus broad, bearing five spines on anterodis-tal margin, with expanded posterodistal lobe; propodus broad-ly expanded, anterior margin unarmed, with posterior mar-ginal setae; palm convex, defined by large and blunt cusp, with one spine near defining corner; dactylus fitting palm.

Coxa of gnathopod 2 ( Fig. 2B ) subquadrate; basis bearing anterodistal lobe; ischium with subcircular lobe; merus slight-ly extended; propodus very large, anterior margin convex; palm oblique, subequal as long as posterior margin, with dis-tal truncate process having one spine and several setae, whole of palm bearing spines; dactylus fitting palm.

Coxa of pereopod 2 ( Figs. 2C , 3A ) widest in middle, with posteroproximal excavation; propodus bearing pair of lock-ing spines, locking spines subequal in size, heavily striated.

Basis of pereopods 3 - 5 ( Figs. 2D - F , 3B ) broad, subcir-cular, weakly serrate on posterior margin; merus and carpus slender; propodus having pair of locking spines, proximal locking spine larger than distal one, locking spines weakly striated.

Peduncle of uropod 1 ( Fig. 3C ) as long as rami, having large distolateral spine and marginal spines; inner and outer rami with three dorsal spines, respectively.

Peduncle of uropod 2 ( Fig. 3D ) almost as long as rami, having marginal spines; inner and outer rami each with two dorsal spines.

Peduncle of uropod 3 ( Fig. 3E ) about 1.5 times as long as ramus, bearing five inner marginal setae and two apicodor-sal spines; ramus with six apical spines.

Telson ( Fig. 3F ) completely cleft, both lobes having four small setae on lateral margin.

Female: Body 6.12 mm long, slightly smaller than that of male.

Basis of gnathopod 1 ( Fig. 3G ) weakly swollen anterodis-tally; propodus slender, subrectangular, middle part of pos-terior margin concave; palm oblique, simple; dactylus fitting palm.

Gnathopod 2 ( Fig. 3H ) similar to gnathopod 1, rather lar-ger.

Pereon segment 2 ( Fig. 3I ) bearing split-like preamplexing notch; posterior lobe strongly expanded forward, and over-lapping with anterior lobe; without locking slit on surface.

Distribution. Korea (Jeju Island), Japan.

Remarks. Protohyale pumila ( Hiwatari and Kajihara, 1981) is similar to P. laie (Barnard, 1970) and Hyale latimana Hi-watari, 2003. Each of the three species has a defining large and blunt cusp on the palm of male gnathopod 1, and one spine on the defining corner. However, the case of P. laie and H. latimana , the anterodistal margin of the propodus of male gnathopod 1 is tumid in shape, whereas that of P. pu-mila is not. In P. laie and H. latimana , there is no process on the palm of the male gnathopod 2, whereas there is a distinct truncate process in P. pumila . In P. laie , the palm of male gnathopod 2 is much longer than the posterior margin, where-as that of each of P. pumila and H. latimana is almost as long as the margin.

The characteristics of our specimens coincide with those shown in Hiwatari and Kajihara’s original description based on specimens from Japan. Minor differences were observed in the shape of the carpus of gnathopod 1 and the ischium of gnathopod 2. The shape of male specimens was more round-ed compared to that of the original description.

Recently, the large genus Hyale in the family Hyalidae was revised by Bousfield and Hendrycks (2002) based on North Pacific fauna. They proposed five new genera from the genus Hyale . Now, six genera, Hyale Rathke, 1837 , Apohyale Bousfield and Hendrycks, 2002 , Protohyale Bousfield and Hendrycks, 2002 , Ptilohyale Bousfield and Hendrycks, 2002 , Ruffohyale Bousfield and Hendrycks, 2002 , and Serejohyale Bousfield and Hendrycks, 2002 , are valid ( Serejo, 2004). Of these, the genus Protohyale was split into four subgenera: Boreohyale, Diplohyale, Leptohyale and Protohyale . In the revision by Bousfield and Hendrycks (2002), Hyale pumila was transferred as Protohyale (Boreohyale) pumila . However, Hughes and Lowry (2006) did not follow the subgeneric status of Bousfield and Hendrycks (2002), because the subgeneric taxonomy of Protohyale does not completely cover the Australian species. Therefore, they combined four subgenera into the genus Protohyale . In this study, we placed our spe-cies pumila in the genus Protohyale following the scheme of Hughes and Lowry.

Figures

Fig. 1. Protohyale pumila (Hiwatari and Kajihara), male. Body. Scale bar=1 mm.

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

Fig. 3. Protohyale pumila (Hiwatari and Kajihara), male. A, Locking spines of pereopod 2 propodus; B, Locking spines of pereopod 5 propodus; C, Uropod 1; D, Uropod 2; E, Uropod 3; F, Telson. Female. G, Gnathopod 1; H, Gnathopod 2; I, Preamplexing notch of peraeon 2. Scale bars: A, B=0.05 mm, C, D, G, H=0.3 mm, E, F=0.1 mm, I=0.2 mm.