taxonID	type	description	language	source
03B9879FF53F8E61FC2EFF7A487D27C9.taxon	diagnosis	DIAGNOSIS (adapted from Capa et al. 2012). — Cylindrical head, anteriorly truncated, terminal mouth extending mid-ventrally as an elongated slit and presence of ventral pharyngeal organ. Breakage groove between first and second chaetiger. Y-shaped oesophageal commissure. First three segments uniramous, with capillaries on notopodia. Following segments biramous, notopodia with capillary chaetae only and neuropodial uncini with two obliquely arranged teeth.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FC2EFF7A487D27C9.taxon	type_taxon	T YPE SPECIES. — Galathowenia africana Kirkegaard, 1959, by original designation.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FC2EFF7A487D27C9.taxon	discussion	REMARKS Galathowenia was established by Kirkegaard (1959) for G. africana, the holotype was collected during the “ GALATHEA’ ’ expedition on the west coast of Africa. In addition to being differentiated based on the shape of the prostomium (anteriorly truncated) with a ventral cleft, G. africana species was characterised by having an “ achaetous peristomium fused with the prostomium, the presence of two eye-spots and three thoracic segments without neuropodial hooks ”. The validity of Galathowenia was later agreed upon by several taxonomists because of the shape of the prostomium (Fauchald 1977; Kirkegaard 1983, 1996; Blake 1984, 2000; Imajima & Morita 1987; Parapar 2003 b). Currently, Galathowenia is featured by having a terminal mouth extending mid-ventrally as an elongated slit, the presence of a breakage groove between the first and the second segments, notopodia with only capillary chaetae on both uniramous and biramous segments, and uncini with a teeth of similar size and generally arranged obliquely (Capa et al. 2012). Among all genera, Galathowenia is more similar to Myriochele because of the lack of distal appendages. However, they can also be distinguished by: 1) the truncated and elongated head of Galathowenia; in contrast to the rounded head of Myriochele; 2) the absence of acicular notochaetae in Galathowenia, which are present in Myriochele; and 3) the presence of a breakage groove between segments 1 and 2 in Galathowenia, which is absent in Myriochele. The species discrimination in Galathowenia is based on: 1) the presence / absence of eyes on head structures; 2) the number, relative length, and distribution of the anterior uniramous thoracic chaetigers; 3) the relative length of the first biramous abdominal segment; 4) the position of the longest chaetiger; 5) the shape and dentition of the uncini; and 6) through the posterior end which bears a different number and structure of lobes.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	description	(Fig. 2) urn: lsid: zoobank. org: act: FB 36 DAA 2 - 35 F 0 - 4 A 14 - 8607 - 4 F 8733 CC 7728	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	materials_examined	TYPE MATERIAL. — Holotype. South China Sea, Malaysia, Terengganu • Kampung Kubang Badak, Kuala Nerus; 5 ° 24 ’ 12.6 ” N, 103 ° 06 ’ 15.5 ” E; 2 - 8 m depth; 24.7.2021; Ibrahim leg.; decantation; UMTAnn 2184.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	materials_examined	Paratypes. South China Sea, Malaysia, Terengganu • 5 specimens; Kampung Kubang Badak, Kuala Nerus; 5 ° 23 ’ 25.7 ” N, 103 ° 06 ’ 59.9 ” E; 24. VII. 2021; Ibrahim leg.; decantation; UMTAnn 2185, LACM-AHF 13506 - 13507, ZRC. ANN 1616 - 1617. ADDITIONAL NON-TYPE MATERIALS. — South China Sea, Malaysia, Terengganu • 44 specimens; Kuala Nerus; St. 1; 5 ° 23 ’ 25.7 ” N, 103 ° 06 ’ 59.9 ” E; 24. VII. 2021; RRC • 5 specimens; Kuala Nerus; St. 2; 5 ° 24 ’ 12.6 ” N, 103 ° 06 ’ 15.5 ” E; 24. VII. 2021; RRC • 20 specimens; Kuala Nerus; St. 3; 5 ° 24 ’ 21.6 ” N, 103 ° 05 ’ 56.7 ” E; 24. VII. 2021; RRC • 20 specimens, Kuala Nerus; St. 4; 5 ° 24 ’ 42.9 ” N, 103 ° 05 ’ 33.4 ” E; 24. VII. 2021; RRC • 11 specimens; Kuala Nerus; St. 5; 5 ° 27 ’ 09.0 ” N, 103 ° 02 ’ 58.4 ” E; 24. VII. 2021; UMTAnn 2328 - 2427.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	etymology	ETYMOLOGY. — The specific epithet was selected after the Latin adjective minuta (- us, - um) meaning tiny, in reference to the body size of the species. The name is proposed in the feminine, to match the gender of the genus (ICZN 1999: Art. 31.2).	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	distribution	DISTRIBUTION. — Known only from the type locality.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	description	DESCRIPTION (based on holotype) Short, slender, thread-like body, cylindrical in cross-section, BL: 10 mm, BW: 0.02 mm, 18 segments. Brownish colour in alcohol, slightly transparent, with some brownish pigmented spots encircling segment 4 immediately after tori (Fig. 2 A). Elongated head, truncated prostomium, terminal mouth extending mid-ventrally as an elongated slit (Fig. 2 A). Two ventrolateral brownish eyespots. First three anterior segments uniramous, each with notochaeta only. First and second segments twice as long as third segment (RLUS 2: 2: 1). White oesophageal commissures, ventral longitudinal band, Y-shaped in anterior segment, extending to segment 5. Anterior biramous segments starting from 4 th segment throughout, three times longer than wide, segment 7 th being longest; following ones becoming posteriorly slightly tapered and shorter, far posterior ones much compressed (Fig. 2 B). Capillary notochaetae on both uniramous and biramous segments decreasing in size ventrally, basally slightly striated, median and distal regions with spinules; typically, more abundant in uniramous segments (3 - 9 capillary chaetae) than in biramous ones (3 - 4 capillary chaetae), the latter with far longer capillary chaetae posteriorly (Fig. 2 E) but single in last three segments. Ventrolateral neurochaetae from segment 4, transverse rows of hooked uncini in long, broad tori (Fig. 2 F, G). Tori along anterior to middle segments longer than wide, with dense oblique rows of uncini (Fig. 2 G); in posterior segments (segment 14 and above) much shorter and smaller, with fewer uncini (less than 20), lying in rows forming oval fields. Bidentate, long-shafted, numerous uncini (around 100) in mid-body (6 th to 7 th) segments, fewer toward posterior end. Long teeth of uncini, nearly equal in size, arranged obliquely because one offset higher (Fig. 2 F, G). Pygidium with terminal anus and two blunt lobes (Fig. 2 B, D). Tube slightly longer than animal, slender, cylindrical in cross-section, composed of thin secreted layer, ornamented with sand grains and fragments of shells (Fig. 2 C, D). VARIATION Number of total segments: 17 - 18. Total body length: 5 - 15 mm. Maximum body width: 0.02 ± 0.002 mm. Most specimens incomplete, laborious to extract from their tubes, especially at the middle and posterior parts, those variations could be greater than reported above. Most specimens lack pigmentation pattern, some have patchy brownish spots on mid-dorsal surface of head and pigmented band entirely encircling distal end of segment 4 (immediately after tori). No prominent constriction or division exists between head and first segment in most of the specimens. The first and second segments have transverse grooves or constrictions. Longest segment, 7, infrequently segments 6 - 9.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	biology_ecology	ECOLOGICAL NOTES Galathowenia minuta n. sp. lives in shallow coastal areas with a depth of 2 - 8 m, inhabiting very fine sands of up to 86.70 %, with a percentage of total organic matter of 1.6 - 6.3 %.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E63FC66F95C494A24C8.taxon	discussion	REMARKS Galathowenia minuta n. sp. can be distinguished from G. annae Capa, Parapar & Hutchings, 2012 based on several features. In G. minuta n. sp. the RLUS is 2: 2: 1, whereas in G. annae it is 1: 2: 1. In G. minuta n. sp. the brown pigmented band presents encircled segment 4, whereas in G. annea, the brownish red pigmented areas is present at the head with some pigmented bands in the four anterior segments. The longest segment in G. minuta is the 7 th segment, whereas, in G. annae, it is the 6 th. Galathowenia minuta n. sp. has two blunt pygidial lobes, whereas G. annae has three prominent digitiform lobes (the dorsal one is slightly smaller than the two lateral ones) (Capa et al. 2012). Galathowenia minuta n. sp. is smaller (5 - 15 mm BL; 0.018 - 0.022 mm BW) than G. annae (5 - 11 mm BL; 0.05 - 0.1 mm BW). In terms of similarity, G. minuta n. sp. has a similar RLUS to that of G. australis (Grube, 1866) and G. oculata (Zachs, 1923), 2: 2: 1. However, they differ by the absence of eyespots and the presence of long and short capillary chaetae in G. australis and a higher number of segments (> 23) as well as a pigmented dorsal head in G. oculata (Parapar, 2003). In addition, segments 5 - 9 are the longest in G. minuta n. sp., with the segment 7 being the longest most frequently, whereas, in G. australis and G. oculata, the segments 4 - 6 and the segment 5 are the longest, respectively. More detailed information regarding the similarities and differences among Galathowenia species worldwide is presented in Appendix 1. The nearest record to Malaysia of Galathowenia species sterns from Indonesia with Owenia lobopygidiata Uschakov, 1950 (currently accepted as G. lobopygidiata (Uschakov, 1950) and G. eurystoma (Caullery, 1944), with the latter then being assigned as Myriochele eurystoma (Caullery, 1944) (Kirkegaard 1956; Parapar et al. 2021; GBIF 2022). Galathowenia lobopygidiata was recorded in the Banda trench, Indonesia and seems doubtful as incomplete specimens (without the anterior part, and only the posterior part being present) were described (Parapar & Moreira 2015). The transfer of the genus Owenia into Galathowenia for lobopygidiata species occurred as Koh et al. (2003) reported an identical anterior end structure for Galathowenia (without a branchial crown) compared with O. lobopygidiata samples from the Zoological Institute, Russian Academy of Science. Regarding the Malaysian specimens, they do not represent G. lobopygidiata as the one recorded in Indonesia, as this species from the Okhotsk Sea locality has nine short, finger-shaped papillae in one row around the anus (Uschakov 1950). In terms of habitat location, G. minuta n. sp. shares the same coastal habitat with G. oculata (12 - 2500 m in depth), G. quelis Capa, Parapar & Hutchings, 2012 (1 - 60 m in depth), and G. annae (13 - 18 m in depth) (Parapar 2003 a; Capa et al. 2012). However, the species has been classified as new based on several distinct morphological characters, especially the RLUS, pigmentation, and anal lobes. Galathowenia minuta n. sp. has RLUS of 2: 2: 1, whereas G. annae, G. oculata and G. quelis have RLUS of 1: 2: 1, 1: 1: 1 and 1: 2: 1, respectively. In addition, G. minuta n. sp. has pigments encircling segment 4, whereas G. annae bears pigments at the anterior four segments. Galathowenia oculata in general has pigments on the dorsal head, whereas G. quelis does not have any pigmentation. Galathowenia minuta n. sp. is completed with two blunt anal lobes, similar to G. quelis. However, G. annae and G. oculata have three prominent digitiform lobes, with one located dorsally and another two located laterally (Capa et al. 2012) (Appendix 1).	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FEA8FEBA4F142689.taxon	diagnosis	DIAGNOSIS (adapted from Capa et al. 2012). — Cylindrical body. Prostomium and peristomium fused forming head. Nuchal organs absent. Mouth terminal or shifted ventrally. Anterior region with one to three uniramous segments, followed by biramous segments. Notopodial chaetae emerging from body wall, capillaries resembling small imbricate scales, smooth acicular chaetae. Tori with irregular rows of bidentate uncini. Parapodial branchiae or cirri absent. Thinsecreted layer tube encrusted with foreign objects. Distinct mitraria larvae. Presence of inter-epidermal nerve cord.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FEA8FEBA4F142689.taxon	type_taxon	TYPE GENUS. — Owenia Delle Chiaje, 1844.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FEA8FEBA4F142689.taxon	discussion	REMARKS Delle Chiaje (1844) described the first oweniid genus and species, Owenia fusiformis Delle Chiaje, 1844. Owenia was proposed in honor of the illustrious British zoologist and paleontologist Richard Owen; whereas the specific epithet refers to the tapered (“ fusiform ”) shape of the worm tube. It seems that the name Owenia was popular during the 19 th century because four other homonymous genera were later proposed in molluscs (Owenia Prosch, 1847), ctenophores (Owenia Kölliker, 1853), birds (Owenia Gray, 1855) and mammals (Owenia De Vis, 1888) (see Rioja 1917), although Delle Chiaje’s name prevails currently, according to the Principle of Priority (ICZN 1999, art. 23.4). In 1846, Grube (1846) established the genus Ammochares Grube, 1846 comprising a single species, A. ottonis Grube, 1846. Subsequently, Malmgren (1867) created the new family Ammocharidae, designating Ammochares as the generic type name. Myriochele Malmgren, 1867 was later inducted into the family. Kinberg (1867) subsequently acknowledged Ammocharidae without referencing Malmgren. Claparède (1868) suggested A. ottonis and O. fusiformis, both described from the Mediterranean Sea, as the same species, hence rendering Ammochares synonymous with Owenia. Rioja (1917) proposed Oweniidae as a replacement name, but this was unnecessary as the family name is unaffected by the synonymy of its type genus (ICZN 1999, art. 40.1). Although Ammocharidae could have remained valid, Oweniidae is considered nomen protectum due to its prevailing use, consistent usage (ICZN 1999: Art. 40.2) and original authorship (ICZN 1999: Art. 40.2.1). Ammocharidae, which was likely last recognised as being valid approximately 90 years ago (Berkeley 1931), is thus categorised as nomen oblitum to ensure nomenclatural stability (ICZN 1999: Art. 40.2). Updated accounts of the anatomy, biology, ecology, morphology, reproduction, phylogeny and taxonomy of this family have recently been reported (Capa et al. 2019; Villalobos-Guerrero 2021; Parapar et al. 2021).	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53F8E61FEA8FEBA4F142689.taxon	discussion	REMARKS Owenia unipinnata n. sp. is the smallest and thinnest species recorded to date (TL: 3 - 10 mm; BW = 0.030 - 0.065 mm). Among all valid Owenia species, the most similar to O. unipinnata n. sp. are O. bassensis Ford & Hutchings, 2005 (from Australia) and O. vieitezi Díaz-Díaz, Parapar & Moreira, 2020 (from north-western coast of the Gulf of Venezuela) based on the presence of three pairs of tentacles. However, O. unipinnata n. sp. differs from O. bassensis mainly because of the presence of one major ramification, the absence of a peristomial collar, the presence of methyl green speckles concentrated on the thorax, and larger body size (length and width) in the Australian species (Parapar & Moreira 2015). Owenia unipinnata n. sp. closely resembles the Venezuelan O. vieitezi species in having three pairs of tentacles and three major ramifications. Nevertheless, each tentacle with the three ramifications is located firstly very close to the crown base, secondly at mid-length, and thirdly very close to the distal end (Díaz-Díaz et al. 2018), which is totally different from that observed for O. unipinnata n. sp. The O. unipinnata n. sp. straightforwardly has three minor and simple ramifications, with the first solitary one situated at the mid-ventral paired tentacle, and another two ramifications located at the dorsal most paired tentacles. In addition, the brown colouration is present in the dorsal and lateral tentacles of the branchial crown of O. vieitezi, and is absent in the O. unipinnata n. sp. Appendix 2 provides more information on the similarities and differences among Owenia species worldwide. REMARKS All oweniid species recorded from the South China Sea are included, with the exception of Galathowenia eurystoma (Caullery, 1944) which remains taxonomically unresolved. The species originally described in the shallow to deep waters of Indonesia (32 - 1570 m) was proposed to be Myriochele (Caullery 1944). However, Capa et al. (2012) stated that it belongs to Galathowenia based on the diagnostic features that characterise this genus. The species was too briefly described using incomplete specimens, hempering its comparison with other species. In addition, considering the broad depth of the distribution range, with specimens presenting pigmentation differences (Caullery 1944), it is likely that more than one species is involved here. Owenia fusiformis (Delle Chiaje, 1844) was scarcely described in samples from the Mediterranean Sea but the type material was never deposited. The species has been recorded at all sea depths and latitudes explored to date (Ford & Hutchings 2005). Nevertheless, detailed morphological analyses of worldwide populations have demonstrated differences that confined its distribution to the original region and the recognition of new species (Koh et al. 2003). Hence, it is likely that O. fusiformis recorded in the SCS represents undescribed species. Owenia collaris (Hartman, 1955) from Southern California, USA, was redescribed by Blake (2000) using type material and its distribution was delimited to that area. Other worldwide records of the species particularly those from the SCS need to be reassessed. Galathowenia lobopygidiata (Uschakov, 1950) was initially described as Owenia based on specimens collected from the deep waters of the Okhotsk Sea, Russia. However, it was later reclassified under the genus Galathowenia because of the remarkable similarity in the head structure within the genus (Koh et al. 2003). Galathowenia lobopygidiata was also reported from Banda Trench, Indonesia. The presence of G. lobopygidiata in the Banda Trench region is possible because the maximum depth of the trench (7440 m) is in the hadopelagic zone, while the Okhotsk Sea of 3372 m is in the abyssopelagic zone. Both regions have similar extreme conditions of high pressure, low temperature and complete darkness. The range of salinity which contributes greatly to the growth and survival rate of polychaetes, may also explain the presence of this species, as the salinity range of the Banda trench and Okhotsk Sea does not differ much (Banda Trench: 34.60 to 34.65 ‰, Okhotsk Sea: 32.5 ‰ and lower) (Radchenko et al. 2010; Suyadi et al. 2018).	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53D8E63FC07FA5E4EBD268C.taxon	diagnosis	DIAGNOSIS (adapted from Capa et al. 2012). — Head with prostomial tentacular crown. Mouth elongated anteriorly. First three segments uniramous with capillaries only. Following segments biramous with capillaries on notopodia and more than 20 irregular rows of bidentate uncini. Teeth arranged side by side on neuropodial tori. Pygidium formed by terminal rim or with a pair of weakly developed lobes. Tube tapered toward both ends, covered by foreign objects imbricated like roof tiles.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF53D8E63FC07FA5E4EBD268C.taxon	type_taxon	TYPE SPECIES. — Owenia fusiformis Delle Chiaje, 1844, by original designation.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	description	(Fig. 3 A-J) urn: lsid: zoobank. org: act: 5117124 A-E 8 A 6 - 48 DB- 9164 - 82382 A 27 F 42 D	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	materials_examined	TYPE MATERIAL. — Holotype. South China Sea, Malaysia, Terengganu • Female; Kampung Kubang Badak, Kuala Nerus; 5 ° 24 ’ 21.6 ” N, 103 ° 05 ’ 56.7 ” E; 2 - 8 m depth, 24. VII. 2021; Ibrahim leg.; decantation; UMTAnn 2186.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	materials_examined	Paratypes. South China Sea, Malaysia, Terengganu • 5 specimens, Kampung Kubang Badak, Kuala Nerus; 5 ° 23 ’ 25.7 ” N, 103 ° 06 ’ 59.9 ” E; 24. VII. 2021; Ibrahim leg.; decantation; UMTAnn 2187, LACM-AHF 13508 - 13509; ZRC. ANN 1618 - 1619. ADDITIONAL NON-TYPE MATERIALS. — South China Sea, Malaysia, Terengganu • 5 specimens, Kuala Nerus, St. 1: 5 ° 23 ’ 25.7 ” N, 103 ° 06 ’ 59.9 ” E, 24. VII. 2021; RRC • 3 specimens; Kuala Nerus; St. 3; 5 ° 24 ’ 21.6 ” N, 103 ° 05 ’ 56.7 ” E; 24. VII. 2021; UMTAnn 2428 - 2435. TYPE LOCALITY. — Kuala Nerus, Terengganu, Malaysia.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	distribution	DISTRIBUTION. — Known only from the type locality.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	etymology	ETYMOLOGY. — The specific epithet is formed by the Latin words uni -, a prefix meaning single or one, and pinnata (- us, - um), which denotes the presence of branches or tentacles. The name of the species refers to the single and isolated tentacle present basally in the ventral-most area of the tentacular crown. The name is proposed in the feminine, to match the genus gender (ICZN 1999, Art. 31.2).	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	description	DESCRIPTION (BASED ON HOLOTYPE) Complete specimen, elongated body, cylindrical in cross-section, BL: 10 mm long, BW: 0.065 mm, 15 segments. Creamy-white colour in alcohol, with no pigmentation. Body divided into three sections: tentacular crown, thorax and abdomen. Short, anteriorly cylindrical, posteriorly tapering and dorsoventrally flattened with two lobes (Fig. 3 A, D). Fragile mid and posterior body, tightly attached to tube by hooks. Short tentacular crown (C / UL ratio c. 0.5), narrow (C / UW ratio c. 0.75), with three pairs of tentacles, slightly longer dorsal-most pair; each tentacle with short, subdistal ramification that slightly lengthens toward dorsal tentacles (Fig. 3 B, C), except mid-ventral paired tentacle proximally with isolated and digitiform ramification (Fig. 3 B); second dichotomy located very close to distal end, with two or three smooth lobe-like tips, with oral grooves present at the third pair of tentacles (dorsal side). Dorsally and ventrally split tentacular crown. Distinct separation between left and right paired tentacles, marked V-shaped slit at mid-ventral side (Fig. 3 B, C). Two brown long elliptical eyespots present lateroventrally at base of crown (Fig. 3 B, C). Junction between thorax and tentacle crown marked by short, barely membranous, straight collar, closely aligned with body wall, without covering eyespots. First and third segments half as long as third segment (RLUS): 1 - 2 - 1. Uniramous segments with three pairs of poorly developed notopodia with capillary chaetae. First and second segments present in a larger number of chaetae and shorter, at ventrolateral position; third and subsequent segments with fewer and longer chaetae located at dorsolateral side, closer to the first biramous notopodia (tori and capillary chaeta). Notochaetae with shafts composed of densely packed scales (Fig. 3 E). Uniramous neuropodia absent. Presence of constriction on 5 th segment. Width of biramous segment decreasing posteriorly, posterior segments short, compact, flattened and tapering off. Poorly developed notopodia in biramous parapodia with capillary chaeta similar to uniramous notochaetae, displaced more dorsally. Gold-coloured notochaetae bundle present from 8 th segment toward posterior end (Fig. 3 D). Neuropodial tori from the 4 th segment, continue toward posterior end; tori wide, with several rows of neurochaetal hooks. Long, narrow and nearly rectangular tori, almost encircling the body, separated only by the notochaetal bundles on dorsal surface (Fig. 3 G). First two biramous segments longer than total uniramous segment length. Longest segment 6 th. Similar neurochaetal uncini throughout, consisting of hooks with shaft ending in two teeth, with left teeth bending toward the right teeth, concave side of teeth bearing approximately 45 ° angles with three bends per tip (Fig. 3 F). Longitudinal lines present at mid ventral (two lines) position, from uniramous region to posterior part. Pygidium flattened with two lobes. Methylene blue stain concentrated at lateral side of collar and less concentrated at lateral side of uniramous region and longitudinal line (Fig. 3 C). Absence of staining at mid-dorsal and ventral collar and thorax (Fig. 3 C). Tube short, and tapered posteriorly; made of overlapping exogenous materials of quartz grains and shell fragments (outer layer), cemented together and arranged like roof tiles (Fig. 3 H). Inner sheath consisting of a translucent successive layers, attached tightly to the neurochaetal hooks. VARIATION Number of total segments: 5 - 13. Total body length: 3 - 10 mm. Maximum body width: 0.03 - 0.065 mm. Some paratypes without simple solitary ramification at mid-ventral paired tentacles. Tips of tentacles completed with two to three small, smooth lobes. Some paratypes with three simple ramifications at the most dorsal paired tentacles. Crown length to thorax ratio either 0.3 or 0.5. Most paratypes without pigments. One of them with less concentrated brown pigmentation at tentacles (with the exception of the base and tip of the crown) and collar (just a band around the dorsal collar). One paratype heavily pigmented at the base of tentacles (with the exception of the tips of the crown), less concentrated at the collar and half-uniramous region. Varying relative length of uniramous segment (RLUS), mostly 1 - 2 - 1. Longest segment either 5 th or 6 th. Posterior segments of a few complete paratypes simply rounded and slightly pointed.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
03B9879FF5338E6DFE8AFF7A480D2689.taxon	biology_ecology	ECOLOGICAL NOTES Owenia unipinnata n. sp. lives in shallow coastal areas of 2 - 8 m in depth, inhabiting moderately (up to 60.47 %) to very fine sandy (up to 86.70 %) bottoms with a percentage of total organic matter in the range of 1.6 - 6.3 %. BIOLOGICAL NOTES Ovigerous females of Owenia unipinnata n. sp. (BW: 0.05 - 0.065 mm; oocyte diameter: 100 - 120 µm) were found in July 2021, during the southwest monsoon season.	en	Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F., Idris, Izwandy (2024): Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species. Zoosystema 46 (20): 513-542, DOI: 10.5252/zoosystema2024v46a20, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2024v46a20.pdf
