Rhopalione rusa, Boyko & Williams, 2024
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publication ID |
https://doi.org/ 10.5252/zoosystema2024v46a7 |
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publication LSID |
lsid:zoobank.org:pub:A7CA7D85-2633-4930-BA12-ACFCB3D0DE21 |
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DOI |
https://doi.org/10.5281/zenodo.10881729 |
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persistent identifier |
https://treatment.plazi.org/id/C780B367-B63A-495A-9951-717DBE2F0549 |
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taxon LSID |
lsid:zoobank.org:act:C780B367-B63A-495A-9951-717DBE2F0549 |
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treatment provided by |
Plazi |
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scientific name |
Rhopalione rusa |
| status |
sp. nov. |
Rhopalione rusa n. sp.
( Figs 10 View FIG ; 11 View FIG )
urn:lsid:zoobank.org:act:C780B367-B63A-495A-9951-717DBE2F0549
“bopyrids under pleon” – Ng & Ahyong 2022: 173 [ex ZRC 2019.0534; specimens examined herein].
“unidentified bopyrid” [of Arcotheres similis ] – Williams et al. 2023: 533 [list].
TYPE MATERIAL. — Holotype. Singapore • ovigerous ♀ (6.8 mm TL), from left side of pleon of female Arcotheres similis (Bürger, 1895) ( ZRC 2019.0534; 6.0 mm CL, 7.6 mm CW), ex Modiolus philippinarum Hanley, 1843 ( Mytilidae Rafinesque, 1815 ); off Changi Beach, intertidal area next to Carpark 7, near ferry terminal; 22.IV.2019; S. K. Tan et al. leg.; ZRC 2023.0259.
Allotype. Singapore • Mature ♂ (4.1 mm TL), collected with holotype; off Changi Beach, intertidal area next to Carpark 7, near ferry terminal; 22.IV.2019; S. K. Tan et al. leg.; ZRC 2023.0260
Paratype. Singapore • 1 ovigerous ♀ (5.5 mm TL; male not present), from right side of pleon of female A. similis (ZRC 2019.0534; 5.6 mm CL, 7.5 mm CW), ex Modiolus philippinarum Hanley, 1843 ( Mytilidae ); off Changi Beach, intertidal area next to Carpark 7, near ferry terminal; 22.IV.2019; S. K. Tan et al. leg.; ZRC 2023.0261.
ETYMOLOGY. — The species is named after the type locality of Changi Beach which, in 1604, was originally called “Tanjong Rusa” (tanjong meaning cape and rusa being Malay for deer which could refer to the extinct Indian muntjac ( Muntiacus muntjak (Zimmerman, 1780)) or the once thought extinct Sambar deer (Rusa unicolor Kerr, 1792). The change of name from Tanjong Rusa to Tanjong Changi occurred between 1604 and 1828 ( Gibson-Hill 1954; Borschberg 2017; https://eresources.nlb.gov.sg/infopedia/articles/ SIP_245_ 2004-12-15. html). The name is a noun in apposition.
DESCRIPTION Female Holotype ( Figs 10 View FIG A-C; 11A-G). Length 6.8 mm; maximal width at posterior margin of pereomere 4 5.0 mm (not including extended coxal plates); head length 0.9 mm; head width 1.4 mm. Body nearly straight ( Fig. 10A, B View FIG ), subcircular in outline but approximately as wide as long when including coxal plates, not distorted; all somites distinct. Head ovate, separated from pereon, 1.6 × wider than long, anterior and posterior margins convex, lateral margins rounded; wide frontal lamina. Eyes absent. Antennules ( Fig. 11A View FIG ) of three articles each, antennae ( Fig. 11A View FIG ) of five articles each, both visible dorsally, few setae distally. Maxilliped ( Fig. 11D View FIG ) longer than wide; broad non-articulated palp with blunt apex; spur elongate, recurved, distally triangular ( Fig. 11D View FIG inset), covered by large round accessory lobe. Barbula ( Fig. 11B View FIG ) laterally with pair of elongate, smooth, broad falcate projections, distally tapering; shallowly convex medially. Pereon nearly straight ( Fig. 10B View FIG ). Pereomeres dorsally distinct, produced laterally into blunt, rounded lobes; widest at pereomere 4; margins weakly curved, mid-dorsal bosses or projections absent; ovoid dorsolateral bosses on pereomeres 1-6, round on pereomere 7, all dorsolateral bosses distinctly separated from lateral portion of pereomeres; ovoid coxal plates on all seven pereomeres, shorter than dorsolateral bosses on pereomeres 1-4, longer than dorsolateral bosses on pereomeres 5-7, dorsolateral bosses and coxal plates in posterior pereomeres not fused. Oostegites completely enclosing brood pouch ( Fig. 10C View FIG ), strongly vaulted ventrally, not protruding beyond anterior margins of body, not visible dorsally. Oostegite 1 ( Fig. 11E, F View FIG ) longer than wide; anterior lobe rounded, larger than distal lobe; internal ridge with few irregular low digitations ( Fig. 11F View FIG ); posterior lobe with acute, triangular distal projection on margin. Oostegite 5 ( Fig. 11C View FIG ) posterior margin fringed with setae. Pereopods isomorphic, subchelate ( Fig. 11E, G View FIG ), small curved dactylus, propodus ovate with scales around region that meets tip of dactylus, carpus and merus triangular, ischium and basis tubular, carpus with distal setae and scales. Pleon short
( Fig. 10B View FIG ), five pleomeres, all dorsally distinct, each with lateral plates produced into long, slender, distally rounded lobes, similar in size and shape to corresponding five pairs of biramous pleopods ( Figs 10B View FIG ; 11C View FIG ); endopodites with small basal swelling (observable in lateral view), decreasing in size on posterior pleomeres. Uniramous uropods ( Fig. 10B View FIG ; 11C View FIG ) similar in size and shape to pleopods and adjacent lateral plates of pleomere 5.
Male
Allotype ( Figs 10D View FIG ; 11 View FIG H-M). Length 4.1 mm; maximal width at pereomeres 2-5 1.3 mm; head length 0.4 mm; head width 0.8 mm. Body elongate, fusiform, straight, length 3.2 × width; all somites dorsally and ventrally distinct ( Figs 10D View FIG ; 11H View FIG ). Head transversely ovate in dorsal view, about half as long as pereomere 1 (along midline) ( Fig. 10D View FIG ); anterior and posterior margins weakly convex; irregularly shaped eyes. Antennules ( Fig. 11I View FIG ) of three articles each, antennae ( Fig. 11I View FIG ) of five articles each, both with terminal setae. Pereomeres 1-7 ( Figs 10D View FIG ; 11H View FIG ) subequal in length, lateral margins rounded, posterior margins straight or at most slightly concave; pereomeres 2-5 subequal in width; pereomeres 1, 6, 7 narrower, subequal in width; midventral projections absent ( Fig. 11H View FIG ). Pereopods isomorphic in size and shape, subchelate, dactyli of anterior two pairs longer than others, all dactyli with setae, propodus ovate, with setae along edge corresponding to region that meets distal end of dactylus, carpus and merus triangular, end of carpus with small setae and scales, ischium and basis tubular ( Fig. 11H, J, K View FIG ). Pleon ( Figs 8C View FIG ; 9I View FIG ) broadly tapering with triangular general outline; pleomeres dorsally and ventrally distinct, distal margins splayed, posteriorly slightly recurved, lateral margins rounded; pleomeres 1-4 with medioventral tubercles ( Fig. 11H View FIG ); pleopods 1-5 ( Fig. 11H, M View FIG ) reniform, uniramous, with minute setae in concave region ( Fig. 11M View FIG ). Pleotelson ( Figs 10D View FIG ; 11H View FIG ) narrow anteriorly, widening posteriorly, indented posteromedially.
REMARKS
Females of Rhopalione rusa n. sp. are most similar to R. racemus n. sp. in the shape of the pereomeres, which are greatly inflated laterally, forming a kind of barbell shape; however, the females differ in the form of the pleopods and lateral plates which are long and slender in R. rusa n. sp. but short and broad in R. racemus n. sp. Additionally, the barbula of females of R. rusa n. sp. bears two subequal lobes whereas that of females of R. racemus n. sp. have the outer lobe much longer than the inner. Males of the two species are also similar with both having five pairs of reniform pleopods but R. rusa n. sp. has midventral tubercles on pleomeres 1-4 whereas R. racemus n. sp. lack midventral tubercles. Rhopalione racemus n. sp. is known only from Discorsotheres subglobosus collected in South Australia (Temperate Australasia) vs Rhopalione rusa n. sp., which is only known from Arcotheres similis collected in Singapore (Central Indo-Pacific) (see Spalding et al. 2007 for discussion of marine ecoregions).
The material of Rhopalione cited by Ng & Ahyong (2022) comprises the type series as designated herein. The holotype female left approximately four puncture holes from the mouthparts in ventral pleomeres 1 and 2 (toward midline) of the host; the paratype female left puncture holes in ventral pleomeres 1 and 2 (toward midline) of the host.
| ZRC |
Zoological Reference Collection, National University of Singapore |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.