identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
46D086CE5BE05E48AC9C004AB8765B3D.text	46D086CE5BE05E48AC9C004AB8765B3D.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Rhynchothorax arenigenus Lee & Park & Park 2025	<div><p>Rhynchothorax arenigenus sp. nov.</p><p>Material examined.</p><p>Holotype. Republic of Korea • 1 ♂; subtidal zone off <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=126.949776&amp;materialsCitation.latitude=33.453945" title="Search Plazi for locations around (long 126.949776/lat 33.453945)">Sunrise Peak (Seongsan Ilchulbong)</a>, Seogwipo-si, Jeju-do; 33°27'14.2"N, 126°56'59.2"E; depth 26.7 m; 24 Oct. 2023; DM Lee leg.; sand sieving, 24 ° C, SCUBA diving; NIBRIV 0000927835 . Paratype. Republic of Korea • 1 ♀; same data for holotype; NIBRIV 0000912890 • 1 ♀; same data as for holotype; NIBRIV 0000927836 • 1 ♂; same data as for holotype; NIBRIV 0000927837 • 1 ♀; same data for holotype; HNIBRIV 23076 .</p><p>Comparative material.</p><p>Rhynchothorax philopsammum Hedgpeth, 1951 . Holotype. USA • 1 ♀; California, Tomales Bay Bluff, Marin County; 27 Jan. 1949; R. J. Menzies leg.; USNM 91245. Paratype. USA • 2 ♀♀; same data for holotype; USNM 91246. Other material. French Polynesia • 5 ♀♀; Reef at Vaitape, Bora Bora, Society Islands; depth 0.5–1 m; 27 Feb. – 06 Mar. 1988; SMF 1080. Colombia • 2 ♂♂, 1 juv.; Magdalena, Punta de Betin, Santa Marta; depth 0–0.5 m; 31 Dec. 1985; under stones and sandy bottom; SMF 1538.</p><p>Description.</p><p>Male. Trunk fully segmented, tapering posteriorly, finely granulated, without dorsal tubercles (Figs 2, 3). Cephalic segment with pair of projections at anterodorsal margin, pair of low tubercles present at middle of neck, cylindrical lateral extension bearing small ectal tubercle (Figs 2 A, 3 A, B). Lateral processes shorter than diameter, separated by half of diameter; small dorsal seta present on center of first lateral process and on dorsodistal margin of other lateral processes (Fig. 2 A, B). First lateral processes with two posterior tubercles; upper tubercle small, present at proximal; lower one large, present at distal. Second lateral processes having smaller anterior tubercle and two similar posterior tubercles. Third lateral processes bearing anterior tubercle and smaller posterior tubercle. Fourth lateral processes with small anterior tubercle. Ocular tubercle absent.</p><p>Proboscis spindle-shaped, having low dorsal protuberance at 2 / 3 from base, with three pairs of dorsolateral swellings, bearing pair of furrows on ventral surface (Figs 2 A, B, 3 A, 4 C); mouth triradiate.</p><p>Abdomen cylindrical, tapering distally, directing horizontally, with nodulous dorsal surface, not reaching distal margin of second coxa (Fig. 2 A, B).</p><p>Chelifores absent.</p><p>Palps five-articled, granular (Fig. 2 C). First article very short. Second article cylindrical, longest, five times as long as diameter, with seta on dorsomedian and dorsodistal margin. Third article cylindrical, 1.5 times length of diameter, without seta. Fourth article distally widened, 3.7 times length of proximal diameter, bearing large dorsal tubercle at 2 / 3 from base, with setae on dorsal, ventral and distal surface; dorsal tubercle 1.5 times as high as proximal diameter of fourth article, armed with three setae. Fifth article bulged proximally on inner side and dorsally, armed with many setae.</p><p>Ovigers 10 - articled, granular (Fig. 2 D). First article short, attached to pectoralis major-like basement (Fig. 4 C). Second article cylindrical. Third article swollen at inner surface. Fourth article tapering at proximal, longest, with setae on outer and distal surface. Fifth article curved, with short setae on outer surface. Sixth article cylindrical, second-longest, with short setae on outer-distal surface. Seventh article distally widened, as long as third article, bearing four tufts of spines on inner- and latero-distal surface (Fig. 3 C). Eighth article bearing four tufts of spines on inner and lateral surface. Ninth article bearing three tufts of spines on inner surface, with seta on lateral surface. Terminal article curved, bearing two tufts of spines on lateral and inner surface, having simple spine and serrated lamina on distal margin, with outer seta. Terminal claw curved, with flattened inner surface (Fig. 3 D).</p><p>Third leg granular, sparsely setose (Fig. 2 E). First coxa as wide as lateral processes, with anterodistal tubercle on first legs; anterodistal tubercle and posteroproximal nodulous ridge on second legs; anterior and posterior tubercles on third legs; small anterior and posterior tubercles on distal margin of fourth legs (Figs 2 A, B, 4 D). Second coxa elongated, longest among three coxae, with large curved tubercle on posterior surface. Third coxa slightly longer than first coxa, with several setae on ventral surface. Femur longest, with long seta on dorsodistal margin. First tibia as long as second tibia, with long seta on dorsodistal margin. Second tibia cylindrical, with long setae on dorso- and ventro-distal margin; dorsodistal seta longer than that of femur and first tibia. Tarsus short, approximately 1 / 6 length of propodus, with long seta on ventral surface. Propodus slightly curved, as long as tibiae, with several setae on dorsal surface, bearing six sole setae, without heel spine. Claw curved, 1 / 3 length of propodus. Auxiliary claws thin, 0.7–0.8 length of claw. Gonopores present on ventral surface of second coxa on fourth legs (Fig. 3 E).</p><p>Measurements (mm). Holotype (NIBRIV 0000927835): Trunk length, 0.76; trunk width, 0.40; proboscis, 0.43; abdomen, 0.16. Paratype (NIBRIV 0000927837): Third leg, first coxa, 0.07; second coxa, 0.12; third coxa, 0.09; femur, 0.20; first tibia, 0.18; second tibia, 0.18; tarsus, 0.03; propodus, 0.17; claw, 0.05; auxiliary claw, 0.04.</p><p>Etymology.</p><p>The species name arenigenus is derived from the Latin “ arena (sand) + - genus (meaning ‘ arising from’ or ‘ born off’) ”, referring to its natural habitat on sandy bottoms. The Korean names for the family, genus, and species are all pronounced “ moraebadageomi ”, emphasizing the association with sandy environments.</p><p>Distribution.</p><p>This species is only known from the type locality, Jejudo Island, Republic of Korea.</p><p>Remarks.</p><p>Rhynchothorax arenigenus sp. nov. closely resembles R. nopperabo Matsushita &amp; Kakui, 2024, R. philopsammum Hedgpeth, 1951, and R. vallatus Child, 1990 in lacking both ocular tubercle and dorsal tubercles on the trunk and proboscis. However, it can be distinguished from R. nopperabo by the presence of a small seta on each lateral process, two posterior tubercles on the first lateral processes, lateral process intervals about half the diameter, and a small tubercle on both the anterior and posterior margin of the first coxa on the fourth legs, whereas in R. nopperabo, no seta is present on the lateral processes, only a posterior tubercle is present on the first lateral processes, the intervals are narrower, and the first coxa of the fourth legs has only a small posterior tubercle (or none).</p><p>Although R. nopperabo was originally described as lacking an ectal tubercle on the lateral extension of the cephalic segment and bearing only an anterodistal tubercle on the first coxa of the second legs and a posterior tubercle on that of the third legs (Matsushita and Kakui 2024), Dr. Keiichi Kakui kindly re-examined the type specimens of R. nopperabo deposited in the Invertebrate Collection of the Hokkaido University Museum and confirmed the presence of intraspecific variations (personal communication, see Table 2).</p><p>Compared to R. philopsammum, the ectal tubercle on the cephalic segment of the present species is smaller and less conspicuous, and the lateral process intervals are wider (Fig. 5). The fifth segment of the palp is dorsally bulged but does not reach the height of the dorsal tubercle on the fourth segment, while in R. philopsammum, the fifth segment is strongly curved, reaching the dorsal tubercle on the fourth segment. Rhynchothorax arenigenus sp. nov. also differs from R. vallatus in several traits: it has a shorter fifth palp segment, tufts of oviger spines with a formula of 4-4 - 3, a posteroproximal nodulous ridge on the first coxa of the second legs, distinct anterior and posterior tubercles on the first coxa of the third legs, and relatively longer auxiliary claws. In R. vallatus, by contrast, the fifth palp segment is more curved and reaches the height of the dorsal tubercle on the fourth segment, the strigilis bears simple spines with a formula of 2-1 - 1, posterior swellings or tubercles are absent on the first coxa of the second and third legs, and the auxiliary claws are shorter.</p><p>The present species exhibits sexual dimorphism in external morphology (Fig. 4 A, B). Female specimens display similar or slightly larger trunk lengths compared to males (females NIBRIV 0000912890, NIBRIV 0000927836, HNIBRIV 23076: 0.83 mm, 0.86 mm, and 0.88 mm, respectively; males NIBRIV 0000927835 and NIBRIV 0000927837: 0.76 mm and 0.83 mm, respectively). Tubercles or projections, such as those on the lateral extension of the cephalic segment, the posterior surface of the first lateral processes, the first and second coxa of the third legs, are less prominent in females. Female gonopores are large and located on the inner surface of the second coxa of the fourth legs, whereas male gonopores are small and situated ventrally on the same coxa (Fig. 3 F).</p><p>Mitochondrial cox 1 sequence analysis revealed very low intraspecific genetic distances (0–0.17 %) between male and female specimens, whereas interspecific distances range from 24.45 % (between R. arenigenus sp. nov. and R. sidereus) to 31.07 % (between R. crenatus and R. sidereus) (Table 3). Considering that male and female specimens were collected from the same locality, that they share key diagnostic morphological characters of the new species, and that they exhibit very low genetic divergence, the morphological differences mentioned above are interpreted as sexual dimorphism.</p></div>	https://treatment.plazi.org/id/46D086CE5BE05E48AC9C004AB8765B3D	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	Lee, Damin;Park, Jin-Ho;Park, Taeseo	Lee, Damin, Park, Jin-Ho, Park, Taeseo (2025): Description of new sand-dwelling Rhynchothorax species (Pycnogonida, Rhynchothoracidae) from Korean waters with note on novel morphological traits. Zoosystematics and Evolution 101 (4): 2055-2064, DOI: 10.3897/zse.101.167593
