identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
26F5CA5FC41F5D87B5C25DEBA853542E.text	26F5CA5FC41F5D87B5C25DEBA853542E.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Sthenelais onca Sibaja-Cordero & Miranda-García 2026	<div><p>Sthenelais onca sp. nov.</p><p>Figs 3, 4, 5</p><p>Specimens examined.</p><p>Holotype: Costa Rica • Guanacaste, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-85.65759&amp;materialsCitation.latitude=10.76492" title="Search Plazi for locations around (long -85.65759/lat 10.76492)">Naranjo Beach</a>; 10°45'53.712"N, 85°39'27.323"W; 0 m a. s. l.; 25 Feb. 2016; J. Sibaja leg., J. C. Azofeifa leg., Y. Vega leg., G. Ampié leg.; sand, low tide, fixed in 95 % ethanol; Process ID: BMAR 014-17; GenBank: PX 556434; MZ- UCR -387-07 . Paratypes: Costa Rica • 3; Guanacaste, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-85.65759&amp;materialsCitation.latitude=10.76492" title="Search Plazi for locations around (long -85.65759/lat 10.76492)">Naranjo Beach</a>; 10°45'53.712"N, 85°39'27.323"W; 0 m a. s. l.; 25 Feb. 2016; J. Sibaja-Cordero leg., J. C. Azofeifa leg., Y. Vega leg., G. Ampié leg.; sand, low tide, fixed in 95 % ethanol; BOLD Process ID: BMAR 008-17, BMAR 009-17, BMAR 015-17, GenBank: PX 556436, PX 556435, PX 556433; MZ- UCR -387-01, MZ- UCR -387-02, MZ- UCR -387-08 . Costa Rica • 3; Guanacaste, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-85.67531&amp;materialsCitation.latitude=10.790431" title="Search Plazi for locations around (long -85.67531/lat 10.790431)">Naranjo Beach</a>; 10°47'25.55"N, 85°40'31.12"W; 0 m a. s. l.; 11 May. 2024; J. Sibaja-Cordero leg., W. Miranda-García leg.; sand, low tide, fixed in 95 % ethanol; BOLD Process ID: BMAR 6330-25; GenBank: PX 556432; MZ- UCR -2528-04 . BIN: ADL 0665 for all specimens.</p><p>Description.</p><p>Holotype (MZ- UCR 387-07) complete, well preserved, 67 mm long, 3.6 mm wide, 174 chaetigers. Paratypes well preserved, (MZ- UCR 387-01, 387-08, 2528-04) complete, (MZ- UCR 387-02, 2528-04) incomplete, 22-110 mm long, 2.4-4 mm wide, 83-197 chaetigers. Left chaetigers 3, 4, and 60 extracted for characterization. Live coloration with faint orange, dorsal median line; lateral grayish longitudinal striations present. Color in alcohol yellow to whitish (Figs 3 A, 4 A).</p><p>Prostomium: Prostomium with small lateral auricles on ceratophore of median antenna (Fig. 3 B). Two pairs of eyes present, one dorsal and one anterior-dorsal pair between the median antenna and first chaetiger (Fig. 3 B). Palps extending ventrally to about segments 15-16 (Fig. 3 C). Live coloration orange (Fig. 4 B).</p><p>Parapodia: Biramous. Anterior parapodia closely together, slightly smaller than those of midbody segments; posterior parapodia gradually decreasing in size and becoming more closely spaced (Fig. 3 A, D). First chaetiger directed anteriorly, bearing a dorsal tentacular cirrus three times larger than ventral tentacular cirrus (Fig. 3 C), and a small dorsal tentacular crest (Fig. 3 A).</p><p>In following chaetigers, ventral cirri two times smaller than dorsal tentacular cirri, mostly smooth, with small distal protuberances (Fig. 4 C). Stylodes without papillae, with digitiform extensions on notopodial bract (Fig. 5 A) and on neuropodial lobes of chaetiger 4; in median and posterior segments, single stylodes present on notopodial bract and on anterodorsal bract of neuropodium.</p><p>Chaetae: Notochaetae serrated, with capillary unidentate tips. Neurochaetae arranged in distinct fascicles. Dorsalmost supra-neuroacicular fascicle consists of three to eight simple spinose spinigers (Fig. 5 C). Remaining supra-neuroacicular fascicles with multiarticulated falcigers. Sub-neuroacicular fascicle of articulated single-bladed falcigers present (Fig. 5 D), plus a more ventral fascicle of long, multiarticulate falcigers. Multiarticulate falcigers with six to eight articles (Fig. 5 E). Articulate and multiarticulate falcigers bidentate. All falciger types lack serrations on shaft (Figs 4 D, 5 D – E).</p><p>Elytra: Elytra subreniform, lateral borders with a row of filiform papillae (Fig. 5 F). Pale in the inner region, bordered by low, rounded, dark gray microtubercles. First pair of elytra with rounded superior margins, covering and extending beyond prostomium (Fig. 3 B). Elytra absent on segments 3, 6, and 8, alternating with segment 27. Following anterior elytra with a notch (Fig. 4 B) on supra-interior margin, gradually diminishing and disappearing by segment 27. Anterior elytral length decreasing posteriorly to segment 27, constant from segment 27 onwards. Cirriform ciliate branchia present lateral to elytral insertion.</p><p>Pygidium: Caudal cirri absent, loss cannot be ruled out (Fig. 3 D).</p><p>Remarks.</p><p>Sthenelais onca sp. nov. is distinguished from other Sthenelais species from the region and surrounding areas by the lack of serrations on the chaetal shaft throughout the body (see Suppl. material 3); for example, S. helenae and S. fusca have multiple spinose rows on the chaetal shaft. Genetically, S. onca sp. nov. is most similar to S. limicola, and both species share smooth chaetal shaft of neurochaetae. They differ in geographic distribution and elytral morphology. Sthenelais onca sp. nov. has a notch on the supra-interior margin of the anterior elytra, whereas S. limicola has a notch on the outer margin of posterior elytra (Barnich and van Haaren 2021).</p><p>Sthenelais onca sp. nov. differs from congeners with smooth-shafted chaetae by its subreniform elytra with a distinct anterior notch, a pale background with a dark gray shade, and consistently bidentate compound neurochaetae. Elytral differences among these species include the absence of a notch ( S. anocula Day, 1973) or a different position of the notch, as in S. limicola Ehlers, 1864 (Barnich and van Haaren 2021); differences in elytra coloration ( S. chathamensis Knox, 1960; S. gracilis Verrill, 1879; S. malayana Horst, 1917); elytra lobulations in the margins ( S. filamentosus Ditlevsen, 1917; S. pectinata Thomassin, 1970); and triangular shape of the first elytra ( S. blanchardi). Neurochaetal differences include the absence of bidentate tips in S. anocula, capillary-tipped neurochaetae in S. gracilis, and unidentate tips in S. filamentosus and S. chathamensis .</p><p>Habitat.</p><p>Intertidal zone, sandy beach. Buried in sand of the surf and saturated zones. Playa Naranjo, Guanacaste, Costa Rica.</p><p>Etymology.</p><p>The specific epithet onca is a noun in apposition referring to the jaguar ( Panthera onca), which is also found in Playa Naranjo, Costa Rica. Sthenelais onca sp. nov. bears elytra with a ringed pattern and a sandy and dark gray color scheme resembling the jaguar’s coat (Fig. 4 A, B). This polychaete is presumed to be a predator (Rouse et al. 2022), as is the jaguar, which preys upon sea turtles that visit the beach, and other animals in Playa Naranjo (Montalvo et al. 2020).</p></div>	https://treatment.plazi.org/id/26F5CA5FC41F5D87B5C25DEBA853542E	Public Domain	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.		Pensoft via Plazi	Sibaja-Cordero, Jeffrey A.;Miranda-García, Waiomi	Sibaja-Cordero, Jeffrey A., Miranda-García, Waiomi (2026): Sthenelais onca sp. nov. (Phyllodocida, Sigalionidae) from a sandy beach on the North Pacific coast of Costa Rica. ZooKeys 1278: 73-93, DOI: 10.3897/zookeys.1278.176443
