Onuphis landanaensis Augener 1918
Creators: name: Arias, Andrés
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Onuphidae
Onuphis
Onuphis landanaensis

description: Onuphis landanaensis Augener, 1918 emended
Figures 2 C, D, 3, 13; Tables 1, 2
Onuphis landanaensis Augener, 1918: 339 –343, Tafel V Figs. 135–138, Tafel VI Fig. 197, Textfig XXXVL.
Type material. Lectotype (ZMH V.8674), Whydah, Benin, West Africa, coll. A. Hupfer (prior to 1917); paralectotype (ZMH P 27822), same data as lectotype.
Type locality. Off Whydah, Benin, Gulf of Guinea, West Africa, tropical eastern Atlantic.
Diagnosis. Prostomium anteriorly extended, one pair of small eyespots present at anterolateral end of prostomium. Palps reaching chaetiger 1, lateral antennae reaching chaetiger 8–9 and median antenna reaching chaetiger 2–3. Ceratophores long and strongly ringed, palpophores with 14–15 rings, lateral antennophores with 17–19 rings and median antennophore with 14–15 rings. Subulate ventral cirri in first six chaetigers; distinct subulate postchaetal lobes in first 10 chaetigers. Tridentate pseudocompound hooks in first two chaetigers, slender long-appendaged hooks absent. Subacicular hooks from chaetiger 9. Flat, distally oblique pectinate chaetae with 10 teeth from chaetiger 9. Single branchial filaments from chaetiger 1 to 19–20, thereafter number increasing rapidly to maximum of three to four. Peristomium and first five chaetigers brown coloured and following chaetigers with two brown transverse bands per segment, anterior band wider than second.
Description. Based on lectotype, with variation of paralectotype included. Small and slender species. Both type specimens incomplete. Length of lectotype 5.2 mm for 37 chaetigers, width 0.4 mm; paralectotype 7.5 mm long, 0.5 mm wide with 43 chaetigers.
Colour pattern consisting of peristomium and first five chaetigers completely brown coloured and following chaetigers with two brown transverse bands per segment, anterior band wider than the second, posterior band sometimes broken into two lateral patches (Figs 2 C, D; 3 A).
Prostomium subtriangular with pair of conical frontal lips (Fig. 13 A). Small pair of eyespots present, situated close to bases of lateral antennae (Fig. 13 A). Palps reaching chaetiger 1 with 13–14 basal rings and longer distal ring in palpophores. Lateral antennae reaching chaetiger 8–9 with 16–18 basal rings in antennophores, median antenna reaching chaetiger 2–3 with 13–14 basal rings in antennophore, all three antennophores with longer distal ring (Fig. 2 D). Palpostyles and antennostyles with irregular longitudinal rows of sensory buds. Nuchal grooves straight with narrow mid-dorsal separation. Peristomial cirri inserted distally on peristomium slightly lateral to lateral antennae, longer than peristomium, not exceeding anterior margin of prostomium.
Anterior chaetigers (1–3) slighty longer than those following (Figs 2 C, D; 3 A). First three pairs of parapodia modified, not enlarged, directed slightly anterolaterally, with low prechaetal fold, triangular prechaetal lobe and spindle-shaped postchaetal lobe, longer than base of parapodium; digitate dorsal cirrus and ventral cirrus about as long as postchaetal lobe (Fig. 3 B). Subulate ventral cirri in first six chaetigers and pad-like thereafter. Postchaetal lobe as distinct subulate lobe in first 10 chaetigers, becoming smaller and conical in shape thereafter. Interramal papilla at base of dorsal cirrus absent.
Branchiae as single filament from first chaetiger to chaetiger 19–20 (Fig. 3 B), then number of filaments increasing rapidly to maximum of three by chaetiger 40.
Aciculae yellowish with pointed tips, usually three per parapodium. Hooded pseudocompound hooks in first two chaetigers. First two parapodia (Fig. 3 B) with following chaetal complement from superior to inferior part of chaetal fan: one to two simple chaetae, three protruding distal tips of aciculae, two to three slightly longappendaged tridentate pseudocompound hooks (Figs 3 G, 13B, C), two to three short-appendaged tridentate pseudocompound hooks (Fig. 13 D). All hooks of almost equal thickness. Pseudocompound hooks replaced by limbate chaetae from chaetiger 3. Flat, distally oblique pectinate chaetae with about 10 teeth from chaetiger 9, usually single (Fig. 13 E). Hooded bidentate subacicular hooks from chaetiger 9 (Fig. 3 F). Mandibles (Fig. 3 D) with white calcified cutting plates and slender shafts. Maxillary formula: Mx I = 1 + 1, Mx II = 8 + 7, Mx III = 8 + 0, Mx IV =?7 +?7, Mx V = 1 + 1, Mx VI absent (Fig. 3 E).
Distribution and ecology. In the original description by Augener (1918), O. landanensis was reported as having a wide distribution in West Africa, from Liberia to Angola. However, herein its distribution is restricted to the shallow subtidal sandy bottoms of Whydah (the type locality of the lectotype) in Benin, inner part of the Gulf of Guinea, West Africa, tropical eastern Atlantic.
Remarks. Onuphis landanaensis was synonymised with O. eremita by Fauvel (1923) and has been regarded as such for nearly a century. But re-examination of the syntypes of O. landanaensis in the ZMH (Hamburg) revealed the presence of not just one, but two species morphologically different from O. eremita. Of these two species, one differs considerably from the original description and thus it is described as a new species, O. augeneri sp. nov. (see above) and the other, represented by two specimens from Whydah, Benin, displays a number of features that aligns it with the original description by Augener (1918). Since Augener (1918) did not choose a holotype, I have designated a lectotype and one paralectotype and thus formally reinstated O. landanaensis. The main difference between the lectotype and paralectotype herein designated and the data from the original description is the number of anterior chaetigers with pseudocompound hooks, being two in the lectotype and paralectotype and reported as three in Augener’s description. This mistake can be easily explained, since at that time the possession of hooks on the first three chaetigers was considered a generic character of Onuphis, and often it was taken for granted. The remaining features fit quite well with the description and illustrations in Augener (1918) (Fig. 3). Another small difference is related to the number of branchial filaments, reported as five or six by Augener (Fig. 3 C) and appearing as maximum of three in the lectotype and paralectotype. However, this is not a major issue since the number of branchial filaments is a growth-related feature and the statement could have related to a larger specimen.
Onuphis landanaensis can be readily distingished from the type species (O. eremita) by the possession of only two anterior chaetigers with pseudocompound hooks (three in O. eremita), the absence of slender long-appendaged ones and the interramal papillae at base of dorsal cirri (both characters present in O. eremita) and the appearance of the SAHs from chaetiger 9 (from chaetiger 10 in O. eremita). Other distinguishing features between these two species and the other eastern Atlantic members of the O. eremita complex are summarised in Table 1. Onuphis landanaensis closely resembles O. augeneri sp. nov. and O. texana but differ from these two species by having only tridentate pseudocompound hooks on the first two chaetigers. Additional distinctive characteristics among these three species are presented in Table 2.
description: Published as part of Arias, Andrés, 2016, Onuphi s and Mooreonuphis (Annelida: Onuphidae) from West Africa with the description of three new species and the reinstatement of O. landanaensis Augener, 1918, pp. 481-511 in Zootaxa 4168 (3) on pages 501-502, DOI: 10.11646/zootaxa.4168.3.3, http://zenodo.org/record/155271