Laonice ayseniensis Delgado-Blas & Díaz-Díaz & Rozbaczylo 2024
Creators: name: Delgado-Blas, Vi ́ Ctor Hugo
name: Díaz-Díaz, Oscar
name: Rozbaczylo, Nicolás
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Spionida
Spionidae
Laonice
Laonice ayseniensis

description: Laonice ayseniensis n. sp
Figure 2A–Q
Type material. Pichicolo, Palena, Hualaihue, Los Lagos region 10/12/2013, 42º02”S, 72º35”W, coll. S. Martínez, slightly gravelly sand, 30 m depth, holotype (MNHNCL ANN-15311) and five paratypes (MNHNCL ANN-15395). Canal Puyuhuapi, Aysén Region (44°19’S, 72°33`W), 30 m depth, eight paratypes (MNHNCL ANN-15396), 09-03- 2014, coll. C. Carreño, gravelly-muddy sediments.
Description. Holotype complete: 147 chaetigers, length 48 mm and width 1.6 mm; paratype complete: 139 chaetigers, length 38 mm and width 1.9 mm; 12 incomplete paratypes: 59–106 chaetigers, length 10–26 mm and width 1.6–2.5 mm.
Prostomium and peristomium fused anteriorly, giving a bicornate, cap-shaped appearance (Fig. 2A); prostomium triangular in the unfused region of the prostomium and peristomium. Peristomium well developed and free from notopodial lamellae (Fig. 2B). One pair of large brownish eyespots, thicker on the lateral region, giving the appearance of raccoon spots on the posterior part of the prostomium (Fig. 2A). Occipital tentacle short, thick, and positioned slightly beyond the notopodial lamellae. Caruncle well developed, extending together with the nuchal organs that start between the notopodium and the prostomium, and accompany the caruncle until chaetigers 14–16 (16 in holotype) (Fig. 2A). Palps absent in all specimens examined.
Branchiae starting from chaetiger 2, continuing up to chaetigers 35–38 (chaetiger 35 in holotype), all branchiae basally free of the notopodial lamellae (Fig. 2E, F, H). All branchiae digitiform, long, thick, with spear-shaped tips, and heavily ciliated; first two pairs of branchiae short (Fig. 2E, F); first pair slightly shorter than the notopodial postchaetal lamellae (Fig. 2E), increasing in length significantly just after the third pair of notolamellae and becoming twice as long as the notopodial postchaetal lamellae from chaetiger 6 (Fig. 2A). From chaetiger 10, the length of the longest branchiae equal to the total width of the body (Fig. 2A, G), thereafter branchiae length gradually decreasing, the last three pairs so small that they are hidden in the parapodium.
Notopodial postchaetal lamellae of chaetiger 1 very small, subtriangular, shorter than neurolamellae and occipital nuchal tentacle (Fig. 2D). From pairs 2–3, lamellae increasing in size to form a broad subtriangular shape (Fig. 2E, F); fourth pair and subsequent pairs even larger and wider, leaf-shaped, the fourth pair a third larger than the third pair, with the tips of the notopodial lamellae touching; fourth pair the largest notopodial lamellae, notopodial lamellae equal in size on chaetigers 13–14, thereafter gradually decreasing in size, becoming rounded from chaetiger 37; from around chaetiger 44 lamellae becoming triangular and gradually decreasing in size until the end of the body. Notopodial prechaetal lamellae rounded, moderately developed (Fig. 2A, E–H), postbranchial lamellae reduced. Dorsal transverse ridges very low, connecting notopodial postchaetal lamellae on chaetigers 37– 48 (Fig. 2C), absent thereafter.
Neuropodial postchaetal lamellae of chaetiger 1 rectangular with rounded edges (Fig. 2D), oval on chaetigers 2–8, with well developed ventral edges in the form of an earlobe, (Fig. 2E–G), increasing gradually in size. Lamellae on chaetiger 9 without ventral lobe (Fig 2I), and on chaetiger 25 lamellae subtriangular, wide, small, until the appearance of the ventrolateral pouches when they become rounded, gradually decreasing in size on posterior chaetigers, with low, rounded lobe.
Ventrolateral pouches starting from chaetigers 35–48 (35 in holotype) and continuing up to chaetiger 57. The first, very small, pouch emerges from the dorsal part of the prechaetal neuropodial lamellae and the posterior dorsal base of the postchaetal neuropodial lamellae.
All anterior parapodia with capillaries arranged in two rows. Long, thin capillary chaetae in the upper part of the notopodium; notopodial chaetae from chaetiger 5 up to chaetiger 22 with chaetae arranged in two rows, anterior row with short, striate and bilimbate chaetae (Fig. 2J), posterior row with long, striate and bilimbate chaetae (Fig. 2K); from chaetiger 23 capillary chaetae arranged in two rows, long, thin, striate unilimbate (Fig. 2L). Neuropodial chaetae similar to notopodial chaetae, arranged in two rows, but shorter and thinner. Neuropodial hooks from chaetigers 35–38, (35 in holotype) with 6–12 hooks per fascicle; hooded hooks tridentate with two teeth on the main fang, giving a bidentate appearance in the lateral view, hoods with distal opening (Fig. 2N, O), companion capillary chaetae present (Fig. 2P). Sabre chaetae from chaetigers 24–28 (28 in holotype) numbering up to three per fascicle; sabre chaetae heavily striate and granulate (Fig. 2M), from chaetiger 15 numbering up to two per fascicle.
Pygidium with two small ventral papilliform cirri arranged closely to each other, and five long cirri: two on one side and three on the other side (Fig. 2Q).
Staining in Methyl Green. Peristomium stained profusely dorsally and ventrally. Anterior segments with outer margin of both notopodial and neuropodial postchaetal lamellae stained (Fig. 2A, A´, B).
Etymology. The specific name ayseniensis is derived from the name of a geographical zone in the Los Lagos Region, Chile.
Distribution Only known from type locality.
Remarks. The ‘ Laonice cirrata’ group (Sikorski & Pavlova 2016: 361) can easily be distinguished by having a prostomium clearly fused with the peristomium on the anterior margin; capillaries on the anterior part of the body arranged in two vertical rows; and by having quite variable numerical characters. Nine species belong to this group: L. cirrata (M.Sars, 1851); L. brevicornis (Kinberg, 1866); L. bahusiensis Söderström, 1920; L. brevicristata Pillai, 1961; L. branchiata Nonato et al., 1986; L. shamrockensis Sikorski, 2003; L. asaccata Sigvaldadottir & Desbruyeres, 2003; L. antipoda Sikorski, 2011; and L. cricketae Sikorski & Pavlova, 2016.
Laonice ayseniensis sp. nov., belongs to the ‘ Laonice cirrata’ group due to the anteriorly fused prostomium and peristomium, the arrangement of the capillaries in the anterior part of the body in two vertical rows. However, Laonice ayseniensis sp. nov., can be distinguished from all other species by having the nuchal organs and caruncle extending up to chaetigers 14–16 (in other species the nuchal organs and caruncle are either shorter (L. brevicristata: to ch. 7–9, L. branchiate: ch. 12, L. shamrockensis: ch. 5, L. asaccata: ch. 4, L. cricketae: caruncle to ch. 1–2 and nuchal organs to ch. 20), or longer (L. cirrata: to ch. 4–40, L. brevicornis: ch. 9–26, L. bahusiensis: ch. 6–35, L. antipoda: ch. 34–38). In addition, the notopodial postchaetal lamellae of chaetiger 1 are very small, subtriangular, shorter than the neurolamellae; the dorsal transverse ridges connecting the notopodial postchaetal lamellae on chaetigers 37–48 are very low; the neuropodial postchaetal lamellae of chaetiger 1 are rectangular with rounded edges, oval on chaetigers 2–8 with earlobe-shaped and well developed ventral edges; the ventrolateral pouches appear from chaetigers 35–48 up to chaetiger 57 (in the other species mentioned, these pouches start on much earlier chaetigers: between chaetigers 3–17, or are absent, except in L. cricketae where they start from chaetiger 40); the hooded hooks have a distal opening; and the pygidium has two small ventral papilliform cirri arranged close to each other, and five long cirri.
Laonice ayseniensis sp. nov., is most similar to L. cirrata, L. brevicornis, L. bahusiensis, and L. antipoda, because they also have a long caruncle and nuchal organs. However, Laonice ayseniensis sp. nov. differs from these species by the morphological characters mentioned above, and by those mentioned below.
Laonice ayseniensis sp. nov., can be distinguished from L. cirrata, L. brevicornis, L. bahusiensis and L. antipoda by the shape and number of eyes, that in Laonice ayseniensis sp. nov., have the appearance of raccoon spots on the back of the prostomium; and by the last three pairs of branchiae that are so small, they are hidden in the parapodium. In addition, Laonice ayseniensis sp. nov. differs from L. cirrata by not having the dorsolateral margin of the notopodial postchaetal lamellae forming a small peak, but having small, triangular posterior notopodial lamellae. Laonice ayseniensis sp. nov. can be distinguished from L. brevicornis by short first two pair of branchiae which are slightly shorter than the notopodial postchaetal lamellae; the presence of dorsal transverse ridges connecting the notopodial postchaetal lamellae; and because the main fang of the hooded hooks is not accompanied at the base by apical teeth.
In addition, Laonice ayseniensis sp. nov. can be distinguished from L. bahusiensis and L. antipoda by having a prostomium that is broadly rounded anteriorly, bicornate as a cap, instead of triangular, anteriorly wide, truncated or slightly incurved, sometimes broadly rounded; sabre chaetae from chaetigers 24–28 vs. from ch. 10–21 in L. bahusiensis, and ch. 14–19 in L. antipoda. Laonice ayseniensis sp. nov. can be further distinguished from L. bahusiensis in having hooded hooks from chaetigers 35–38 vs. from ch. 14–35, and by the number of teeth (tridentate with two teeth on the main fang, appearing bidentate in the lateral view vs. five teeth (tridentate in the lateral view) with very small upper apical teeth. Laonice ayseniensis sp. nov. can be further distinguished from L. antipoda by the presence of nuchal tentacle, fewer pairs of branchiae (34–37 vs. 38–45); and very low (vs. prominent) dorsal transverse ridges.
Hartmann-Schröder (1965) recorded three species for Chile: Laonice cirrata, and two subspecies L. cirrata postcirrata and L. cirrata praecirrata. The first species is already discussed above; and the other two species are very different from the new species.
Laonice ayseniensis sp. nov. can be distinguished from Laonice postcirrata in that the former has an occipital tentacle situated slightly forward of the first pair of notopodial lamellae, whilst L. postcirrata has a tentacle located between the first and second pair of notopodial lamellae; the prostomium and peristomium are completely fused in the anterior part of the prostomium, unlike L. postcirrata where they are not fused. Another difference is in the shape and number of eyes: Laonice ayseniensis sp. nov., has the appearance of raccoon spots on the posterior region of the prostomium, whereas L. postcirrata has two or four small eyes arranged in the same row, or in a square or trapezoid. Laonice ayseniensis sp. nov., also has a caruncle and branchiae that reach chaetigers 14–16 and 35–38 vs. ch. 22–28 and 42, respectively, in L. postcirrata. Furthermore, the shape of the anterior notopodial and neuropodial lamellae are different: in Laonice ayseniensis sp. nov., the notopodial lamellae have a broad subtriangular shape with a blunt tip, and the postchaetal neuropodial lamellae on chaetigers 2–8 are oval with well-developed, earlobe-shaped ventral edges, whilst in L. postcirrata the notopodial lamellae have pointed tips, and the neuropodial lamellae are wide and subtriangular. Ventrolateral pouches appear from from chaetigers 35–48 in Laonice ayseniensis sp. nov. vs. from ch. 11–15 in L. postcirrata (Sirkorski et al., 2016), and finally, Laonice ayseniensis sp. nov. has transdorsal ridges, and the neuropodial hooks and sabre chaetae appear from chaetigers 35–38 and 24–28 vs. ch. 31 and 16, respectively, in L. postcirrata.
Differences compared to other similar species can be found in the key.
description: Published as part of Delgado-Blas, Vi ́ Ctor Hugo, Díaz-Díaz, Oscar & Rozbaczylo, Nicolás, 2024, Laonice Malmgren, 1867 (Annelida: Spionidae) from the Aysén region in southern Chile with description of a new species, pp. 157-166 in Zootaxa 5551 (1) on pages 162-165, DOI: 10.11646/zootaxa.5551.1.7, http://zenodo.org/record/14390215