Sicyonia japonica Balss, 1914

Yang, Chien-Hui, Kumar, Appukuttannair Biju & Chan, Tin-Yam, 2024, On the differences between the two widely distributed and closely related rock shrimps Sicyonia japonica Balss, 1914 and S. parajaponica Crosnier, 2003 (Dendrobranchiata, Penaeoidea, Sicyoniidae), with a new record of S. japonica from Taiwan, Zootaxa 5476 (1), pp. 505-513 : 507-508

Sicyonia japonica Balss, 1914

( Figs. 2A–D , 3A–B , 4A–B )

Sicyonia lancifer var. japonica Balss, 1914: 16 , fig. 9 (type-locality: Japan).

Sicyonia japonica . — Parisi 1919: 66, pl. 5 figs. 10, 13, 14.— Takeda 1982: 10, fig. 30. — Hayashi 1985: 197, figs. 88d, 89d, 90d, 91e; 1986: 81, fig. 41.— Hayashi 1992: 158, figs. 83d, 84d, 85d, 86e.— Crosnier 2003: 223 , figs 6B, C, 8.— De Grave & Fransen 2011: 230.— Chan & Yang 2023: 43, figs 7A, B.

Eusicyoia lancifer japonica .— Kubo 1949: 440, figs. 6C, 8P, 14A, 22G, 30C, D, 48B, 60A–C, 77E–K, 79H, 151, 156A, H.

Eusicyonia cf. lancifer .— Barnard 1950: 821 (p.p.) [not Olivier, 1811].

Sicyonia lancifer .— Kensley 1972: 24, fig. 10a [not Olivier, 1811].

Sicyonia lancifera .— de Freitas 1984: 3, fig. V-1 [not Olivier, 1811].

Not Sicyonia japonica .— Miyake 1982: 14, pl. 6-fig. 3 [= S. lancifer (Olivier, 1811].

Not Sicyonia japonica .— Yu & Chan 1986: 56, 3 unnumbered photos.— Liu & Zhong 1988: 249, fig. 150 [= S. parajaponica Crosnier, 2003 ].

Material examined. Japan: Katakawa , 200–300 m, no date, 1 male (cl 19.2 mm), NTOU M02582 . Ryukyu Islands , KUMEJIMA 2009, stn trawl 25, 26°16.55’N, 126°52.72’E, 151–160 m, 12 Nov 2009, 1 juvenile (cl 3.4 mm), NTOU M02609 ; stn trawl 28, 26°17.02’N, 126°54.04’E, 142–149 m, 13 Nov 2009, 1 juvenile (cl 4.7 mm), NTOU M02583 . Taiwan: Northern Three Islets , commercial trawls, Nov 2021, male (cl 19.4 mm), female (cl 20.7 mm), NTOU M02546 . Madagascar: ATIMO VATAE, stn CP3510 , 25°14.6’S, 47°09.1’E, 79–80 m, 29 Apr 2010, 2 females (cl 12.7 mm, 15.2 mm), MNHN-IU-2010-4951; stn CP3538, 25°22.4’S, 47°02.8’E, 89–95 m, 03 May 2010, 1 male (cl 16.7 mm), 1 female (cl 17.9 mm), MNHN-IU-2010-4015; stn CP3559, 25°33.7’S, 46°08.6’E, 78–80 m, 06 May 2010, 1 male (cl 12.7 mm), MNHN-IU-2010-3996; stn CP3572, 25°11.7’S, 47°12.5’E, 75–77 m, 08 May 2010, 1 male (cl 16.6 mm), MNHN-IU-2010-4944; stn CP3623, 25°41.4’S, 45°59.2’E, 74–80 m, 15 May 2010, 1 female (cl 20.4 mm), MNHN-IU-2010-3993.

Diagnosis. Body robust and shell hard. Rostrum short, not overreaching scaphocerite; tip bifurcate, dorsal margin with 9–11 teeth including 5–7 postrostral teeth, ventral margin with only 1 small subdistal tooth. Carapace postrostral crest high; hepatic tooth well-developed, directed slightly upward; infraorbital lobe rounded. First pleomere tergite with mid-dorsal carina protruded into strong tooth directed forward or upward; second pleomere tergite with anterior end of middorsal carina forming obtuse angle; first to third pleomere pleura only sharply pointed ventrally, otherwise unarmed; fourth and fifth pleomere pleura armed with 2–4 spines on posteroventral margin. Male petasma with distal external process of ventrolateral lobe subcircular; dorsolateral lobe lacking lateral process, external processes horn-like and curved inward, distal internal process lobular and much shorter than external process. Female thelycum greatly protruded anteriorly and with acute tip, posterior part sunken and laterally expanded with smooth margins.

Fresh coloration. Body light to dark brown, dorsal part mottled with black-brown patches and dots of various sizes, ventral part light pink with white patches ( Fig. 2A, C ). Posterodorsal carapace bearing a large distinct reddish brown and somewhat quadrilateral spot while anterior articulated smooth surface of first pleomere tergite with a pair of rectangular black patches covered with light blue iridescent dots ( Fig. 2B, D ). Antennular and antennal flagella alternated with white and reddish brown bands. Tail-fan mostly whitish.

Distribution. Indo-West Pacific, known with certainty from Japan, Taiwan (new record), the Philippines, Somalia, Seychelles (including Amirante Islands), Madagascar and Mozambique ( Fig. 1 ), at depths of 25–300 m (de Freitas 1984; Crosnier 2003).

Remarks. Detailed comparison of the material, including fresh specimens, of S. japonica and S. parajaponica in this study reveals that they have 8.9–9.2% and 1.9–3.0% sequence divergences in the barcoding genes COI (657 bp) and 16S rRNA (427–550 bp), respectively. Although the basic color patterns of these two species are similar, they can be readily separated by the distinct markings on the posterodorsal carapace and the articulated part of the first pleomere tergite. The large reddish brown spot on the posterodorsal carapace is considerably smaller (transverse part less than 1/3 carapace width) and somewhat quadrilateral in S. japonica ( Fig. 2B, D ), but huge (transversely nearly half carapace width) and almost circular (like a Japanese flag) in S. parajaponica ( Fig. 2F ). The articulated part of the first pleomere tergite has a pair of very conspicuous black patches covered with light blue iridescent dots in S. japonica ( Fig. 2B, D ) but there are no special markings in S. parajaponica . Morphologically, still only the shapes of the middorsal carina on the second pleomere tergite and the male petasma proposed by Crosnier (2003) are found to be useful in separating these two species. The anterior end of the middorsal carina on the second pleomere only forms an obtuse angle ( Fig. 3B ) in S. japonica but is sharp, spine-like in S. parajaponica ( Fig. 3D ). The petasma of S. japonica has the distal external process of the ventrolateral lobe semicircular and the distal internal process distinctly shorter than the external process in the dorsolateral lobes ( Fig. 4A, B ). For S. parajaponica , the petasma has the external process of the ventrolateral lobe strongly protruded laterally and triangular while the distal internal and external processes of the dorsolateral lobes are similarly in lengths ( Fig. 4C, D ). With large genetic differences and distinct coloration, the present study supports Crosnier (2003) in treating S. parajaponica as a species distinct from S. japonica .

Within S. japonica , the present study reveals that high genetic differences may accompany its disjunct geographical distribution. The specimens from Taiwan (NTOU M02546 male: GenBank accession no. OR116125) and Madagascar (MNHN-IU-2010-3993: OR116126, MNHN-IU-2010-4015 male: OR116127 and MNHN-IU-2010-4951 larger female: OR116128) have COI sequence (657 bp) divergences of 5.0–5.2% while the sequence similarities amongst three specimens from Madagascar are 99.8–100%. For the 16S gene (550 bp), the two specimens from Taiwan (NTOU M02546 male: OR116177) and Japan (NTOU M02583: OR116178) has 99.5% sequence similarity while the four specimens from Madagascar (MNHN-IU-2010-3993: OR116179, MNHN-IU-2010-3996: OR116180, MNHN-IU-2010-4015 male: OR116181 and MNHN-IU-2010-4951 larger female: OR116182) have identical sequence. However, there are 1.6 to 1.8% sequence divergences between the Taiwan / Japan and Madagascar populations. The basic color patterns as well as distinct color markings are similar between the western Pacific and Madagascar specimens, except the body color of the former is generally darker ( Fig. 2A–D ). The two specimens examined from Kume Island in Japan both have color photographs and their colorations are almost the same as those from Taiwan, same as other published color photograph and figure of this species from Japan ( Takeda 1982: fig. 30; Hayashi 1992: fig. 41). Morphologically, the five specimens examined from Japan and Taiwan all have five postrostal teeth (not including the tooth just above orbit, Figs 2A , 3A ) but the seven specimens from Madagascar have six postrostral teeth ( Fig. 2A ). All published figures and photographs of S. japonica from Japan ( Parisi 1919: 66, pl. 5 fig. 13; Kubo 1949: fig. 151; Takeda 1982: fig. 30; Hayashi 1985: fig. 88d, 1986: fig. 41, 1992: fig. 83d) and the Philippines ( Crosnier 2003: fig. 8A) also show five postrostral teeth. On the other hand, previous figures of S. japonica (as S. lancifer ) from Mozambique all show six postrostral teeth ( Kensley 1972: fig.10A; de Freitas 1984: fig. V-1A). However, no other morphological and color differences can be found between the western Pacific and western Indian Ocean materials. As the present work only has a few specimens from limited localities, more material and genetic data from different areas are necessary to determine if the western Indian Ocean population represents a separate species or subspecies.

It may need to point out that the three specimens from Mozambique reported by Barnard (1950) as “ Eusicyonia cf. lancifer ” are considered as S. japonica by Cronsier (2003). However, the description provided by Barnard (1950) clearly indicated that one of his specimens truly belongs to S. lancifer (Oliver, 1811) in having the third pleomere pleuron tridentate (and bearing more postrostal teeth) while the other two are S. japonica by the third pleomere pleuron unidentate (and having less postrostral teeth).

Figures

FIGURE 1. Global geographic distributions of Sicyonia japonica Balss, 1914 (★) and S. parajaponica Crosnier, 2003 (☆). Symbols within square are records after the revision of Crosnier (2003).

FIGURE 2. A–B, Sicyonia japonica Balss, 1914, Taiwan, male 19.4 mm cl (NTOU M02546); C–D, S. japonica, Madagacar, male 16.6 mm cl (MNHN-IU-2010-4944); E–F, S. parajaponica Crosnier, 2003, India, male 18.2 mm cl (NTOU M02550). A, C & E, left lateral view; B, D & F, dorsal view.

FIGURE 3. Three-dimensional images by micro-computed tomography. A–B, Sicyonia japonica Balss, 1914, Taiwan, male 19.4 mm cl (NTOU M02546); C–D, S. parajaponica Crosnier, 2003, Taiwan, male 16.8 mm cl (NTOU M02589).A & C, entire body, right lateral view; B & D, middorsal carina of first and second pleomere somites, right lateral view.

FIGURE 4. Petasma. A–B, Sicyonia japonica Balss, 1914, Japan, male 19.2 mm cl (NTOU M02582); C–D, S. parajaponica Crosnier, 2003, Taiwan, male 20.1 mm cl (NTOU M02592). A & C, dorsal view; B & D, ventral view.