Naineris elegans, Álvarez & Haggin, 2024

Álvarez, Ricardo & Haggin, Brent M., 2024, Redescription of two species of Naineris (Annelida, Orbiniidae) with multiple dorsal organs and description of a new species from the NE Pacific, Zootaxa 5492 (3), pp. 395-408 : 403-405

Naineris elegans sp. nov.

urn:lsid:zoobank.org:act:DF84D183-FA7D-442D-B0E1-9E193A959555

( Fig. 5 )

Material examined. USA, North Pacific Ocean, California, Los Angeles County, Palos Verdes Peninsula , Lunada Bay , Sta. MBC 20801 , coll. R. Wetzer et al., 18 Feb 2019, ~ 33.769°N, ~ 118.422°W, intertidal algae wash, hand collected, holotype ( LACM-AHF Poly 11164); west of Redondo Beach , Sta. Bight 13 9257, 33.82928°N, 118.416°W, 18 m, soft sediment, van Veen grab, 1.0 mm sieve, coll. Southern California Coastal Water Research Project, 26 July 2013, paratype ( LACM-AHF Poly 13426) .

Measurements: Holotype 37 mm long, 2.2 mm wide, for 84 chaetigers.

Diagnosis. Spatulate prostomium. Multiple dorsal sensory organs oval to rounded, voluminous, seven per side in most chaetigers, with a brown pigmented base; arranged in two distinct groups in the most anterior segments, then forming two subtriangular groups with apex displaced medially in the following ones, reaching each other. Thoracic notopodial lobes pear-shaped with blunt tips. Thoracic neuropodial lobe with an upper rounded papilla. Thoracic neurochaetae with 5–6 transverse, posterior rows of numerous subuluncini; a transverse, anterior row of about 20 crenulate capillaries; an inferior, anterior, oblique row of about 20 hooded uncini and an inferior, posterior, oblique row of capillaries.

Description: A medium-sized species. Color in alcohol pale yellow with a conspicuous brown pigmentation around base of dorsal organs, adopting a V-shaped form in abdominal segments ( Fig. 5A ). Body narrow without width distinction between thorax and abdomen. Changes in parapodia mark distinction between thorax-abdomen. Ventrally thorax smooth, but abdominal chaetigers tri-annulate with central ring widest.

Prostomium spatulate, with rounded borders ( Fig. 5B ); eyespots diffuse; nuchal organs present at posterior end of prostomium and anterior end of peristomium. Peristomium with two achaetous rings well defined ( Fig. 5B ). Mouth opening with lips striated; proboscis wide, multi-lobed ( Fig. 5A–D ).

Branchiae from chaetiger 6, long, cirriform, with fine prolonged apex, glandular, ciliated, with dark pigmentation along axis; thoracic branchiae reaching midline in thoracic segments; abdominal branchiae longer, reaching across the midline to the opposite branchial base in the abdomen. Dorsal sensory organs per segment present from chaetiger 10; oval to rounded, voluminous, seven per side in most chaetigers, with a brown pigmented base ( Fig. 5F ); arranged in two distinct groups in the most anterior segments, then forming two subtriangular groups with apex displaced medially in the following ones, reaching each other ( Fig. 5F ). Dorsal crest reduced, straight, thin, with no evidence of cilia ( Fig. 5A ).

Thorax with 36 chaetigers (~6 transitional segments with intermediate characteristics between thoracic and abdominal segments), dorsoventrally depressed, straight ( Fig. 5C ). Parapodia biramous, interramal papillae and prechaetal lobe absent. Thoracic notopodial lobes pear-shaped with blunt tips ( Fig. 5E ). Abdominal notopodial lobes lanceolate, with evident constriction ( Fig. 5G ). Thoracic neuropodial lobes represented by a flange with upper rounded papillae ( Fig. 5E ). Abdominal neuropodial lobes triangular, laterally projected ( Fig. 5G ).

Thoracic notochaetae include 20–30 crenulate capillaries in two groups ( Fig. 5E ). Abdominal notochaetae with 20–30 crenulate capillaries in two groups; furcate chaetae not observed. Thoracic neurochaetae with seven transverse rows of 20–30 subuluncini and an inferior, oblique row of uncini intermixed with crenulate capillaries ~20–25 each ( Fig. 5E ). Abdominal neurochaetae include 10–15 crenulate capillaries and three acicular spines intermixed.

Pygidium unknown (complete paratype bears four anal cirri as typical in Naineris species.

Variation: Thorax with 35 chaetigers (~4 transitional) and dorsal sensory organs from chaetiger 13 in paratype. Paratype width at chaetiger 50: 1.4 mm.

Remarks: The material examined here were identified as Naineris sp. DC1 (T. Phillips, unpublished data) by SCAMIT. A comparison of these specimens with N. bicornis (type locality Florida, Gulf of Mexico) and N. australis (type locality Adelaide, Australia) showed that the material from the Northeastern Pacific Ocean represents a separate species. Naineris elegans sp. nov. resembles N. bicornis and N. australis in the chaetal arrangement and presence of multiple dorsal organs. However, the thoracic notopodial lobes of N. australis are cirriform, whereas those of N. bicornis are lanceolate, with triangular tips, but pear-shaped with blunt tips in N. elegans sp. nov. ( Fig. 6- C ). Abdominal notopodial lobes also differ; in N. australis , they are cirriform, whereas in N. bicornis and N. elegans sp. nov. they are lanceolate ( Fig. 6D–F ). Another consistent difference between N. elegans sp. nov. and N. bicornis are the thoracic neuropodial lobes. In N. elegans sp. nov. these lobes have a rounded projection, whereas they are a triangular, in N. bicornis ( Fig. 6A–C ).

Etymology: Latin for elegant, referring to the conspicuous delicate multiple dorsal organs, especially those from thoracic segments.

Distribution: USA, Southern California Bight province, Santa Monica Bay; intertidal to 18 m.

Figures

FIGURE 5. Naineris elegans sp. nov. Holotype (LACM-AHF Poly 11164). A, incomplete live specimen, dorsal view; B, anterior end, dorsal view; C, thorax, lateral view; D, thorax, ventro-lateral view; E, thoracic parapodia, lateral view; F, dorsal organs from thorax; G, abdominal parapodia, ventro-lateral view. br—branchia, cc—crenulate capillaries, dc—dorsal crest, do—dorsal organs, NeL—Neuropodial lobe, NoL—Notopodial lobe, pe—peristomium, pr—prostomium, su—subuluncini, u—uncini (Scales: A, D: 1 mm; B, C, E–G: 0.5 mm).

FIGURE 6. Parapodial lobes scheme of species of Naineris with multiple dorsal organs studied. A, thoracic parapodia of Naineris bicornis; B, thoracic parapodia of Naineris australis; C, thoracic parapodia of Naineris elegans sp. nov.; D, abdominal parapodia of Naineris bicornis; E, abdominal parapodia of Naineris australis; F, abdominal parapodia of Naineris elegans sp. nov. NeL—Neuropodial lobe, NoL—Notopodial lobe (Scales: A, D: 250 μm; B, E: 200 μm; C–F: 500 μm).