Naineris bicornis Hartman, 1951

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 : 397-401

publication ID	https://doi.org/ 10.11646/zootaxa.5492.3.6
publication LSID	lsid:zoobank.org:pub:DD79929A-C343-467F-A3AB-31FC7E59705C
DOI	https://doi.org/10.5281/zenodo.13286446
persistent identifier	https://treatment.plazi.org/id/41151731-FF82-4F4C-FF12-E5B085D1841D
treatment provided by	Plazi
scientific name	Naineris bicornis Hartman, 1951
status

Treatment

Naineris bicornis Hartman, 1951 View in CoL

( Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Naineris bicornis Hartman, 1951: 72–74 View in CoL , pl. 19, figs 1–6; 1957: 304–305, pl. 40, figs 1–6; 1959: 366.— Perkins & Savage 1975: 43.— Taylor 1984: 1–9, figs 1–5, 1–6a–f.— Salazar-Vallejo 1996: 26.— Perkins 1998: 88.—Felder & Camp 2009: 764.

Material examined. USA, Florida, Franklin County, Alligator Harbor, Florida, Gulf of Mexico , US, North Atlantic Ocean, Sta. 3, coll. 04 Feb 1950, 29.910000°N, 84.395278°W, holotype ( LACM-AHF Poly 674). GoogleMaps — off Saint George Sound , MAFLA, Sta. 2421, coll. D. Savelle, H. Kritzler, D. Garlick, Sep 1975, 29.62°N, 84.28°W, 19 m, box core (1, USNM 1284135 About USNM ); GoogleMaps MAFLA Sta. 2421, coll. D. Savelle, H. Kritzler, D. Garlick, Sep 1975, 29.616667°N, 84.283333°W, 19 m, box core (1, USNM 1284134 About USNM ); GoogleMaps MAFLA, Sta. 2420, coll. D. Savelle, H. Kritzler, D. Garlick, 1975, 29.6994°N, 84.1836°W, 19 m (1, USNM 1284133 About USNM ); GoogleMaps MAFLA, Sta. 2420, D. Savelle, H. Kritzler, D. Garlick, Jun 1975, 29.6994°N, 84.1836°W, 14 m, (1, USNM 1284132 About USNM ); GoogleMaps MAFLA, Sta. 2420, coll. D. Savelle, H. Kritzler, D. Garlick, 1975, 29.6994°N, 84.1836°W, 14 m (1, USNM 1284131 About USNM ). GoogleMaps —off Cedar Key , MAFLA Sta. 2317, coll. D. Savelle, H. Kritzler, D. Garlick, 19 Sep 1975, 28.933333°N, 84.100000°W, 29 m, box core (1, USNM 1284136 About USNM ; 1, USNM 1284137 About USNM ; 1, USNM 1284138 About USNM ; 1, USNM 1284139 About USNM ). GoogleMaps — off Crystal River , MAFLA Sta. 2316, Nov 1977, 28.700000° N, 84.333333° W, 35 m (1, USNM 090156 About USNM ) (parapodia slides). GoogleMaps — off Florida, SOFLA Sta. 16, coll. Mote Marine Lab For Bureau of the Land Management / Minerals Management Service ( BLM / MMS), Jul 1981, 25.761667°N, 83.184444°W, 54 m (1, USNM 090154 About USNM ); GoogleMaps SOFLA Sta. 02, coll. Mote Marine Lab For BLM/ MMS, May 1981, 26.763889°N, 82.753056°W, 24 m (1, USNM 090153 About USNM ); GoogleMaps SOFLA Sta. 46, coll. Environmental Science and Engineering, Inc. /LGL Ecological Research Associates (Ese / Lgl ) For BLM/ MMS, May 1984, 26.0144 °N, 82.1319°W, 18 m (2, USNM 112302 About USNM ); GoogleMaps SABP Sta. 7B, coll. Texas Instruments for BLM/ MMS, May 1977, 29.4664°N, 80.9525°W, 20 m (1, USNM 59369 About USNM ); GoogleMaps MAFLA Sta. 2960, Nov 1977, 25.67°N, 82.33°W, 27 m (1, USNM 90164 About USNM ). GoogleMaps — off St. Petersburg , MAFLA Sta. 2207, coll. Aug 1977, 27.950000°N, 83.150000°W, 19 m, (1, USNM 090155 About USNM ). GoogleMaps — off Apalachicola Bay , MAFLA, Sta. 2316, coll. D. Savelle, H. Kritzler, D. Garlick, Jul 1975, 28.7003°N, 84.3336°W, 35 m, (2, USNM 1284140 About USNM ; 1, USNM 1284141 About USNM ; 1, USNM 1284670 About USNM ); GoogleMaps MAFLA, Sta 48, coll. DG., Jun 1974, 28.48°N, 84.35°W (2, USNM 1284677 About USNM ); GoogleMaps MAFLA, Sta 42, coll. DG., Jun 1974, 28.7°N, 84.44°W (1, USNM 1284679 About USNM ). GoogleMaps — off Clear Water , MAFLA, Sta. 2207, coll. D. Bishof, D. Savelle, Jul 1975, 27.9497°N, 83.15°W, 19 m, (1, USNM 1284671 About USNM ); GoogleMaps MAFLA, Sta. 2209, coll. D. Bishof, D. Savelle, Jul 1975, 27.875°N, 83.5667°W, 34 m, (3, USNM 1284672 About USNM ). GoogleMaps — off Charlotte Harbor , MAFLA, Sta. 2104, coll. D. Bishof, D. Savelle, May 1975, 26.4164°N, 83.3833°W, 53 m, (1, USNM 1284678 About USNM ). GoogleMaps — off Sanibel Island , MAFLA, Sta. 2101, coll. D. Bishof, D. Savelle, May 1975, 26.4167°N, 82.4169°W, 11 m, (1, USNM 1284683 About USNM ) GoogleMaps .

Measurements. Holotype is fragmented in three parts. The most anterior 0.75 mm long, 3 mm wide, for 27 chaetigers. Hartman (1951) and Taylor (1984) reported animals reaching 30 mm length and 5 mm width for over 100 segments for specimens from the same localities and sampling events studied.

Diagnosis. Spatulate to slightly indented prostomium. Multiple dorsal sensory organs grouped ten per side in a one row anteriorly, increasing to two on posterior thoracic segments, almost crossing midline; abdominal sensory organs forming two distinct groups irregularly arranged, reduced in number (four to five). Thoracic notopodial lobes may be acute-to-rounded-tipped and with median restriction. Thoracic neuropodial lobe with an upper subtriangular 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.

Redescription. Holotype medium-sized specimen. Color in alcohol pale yellow. Thorax and abdomen distinct, with parapodia inserted laterally in thorax and dorsally in abdomen. Most abdominal branchiae lacking. Ventrally thorax smooth, but abdomen tri-annulate with central ring wider than others.

Prostomium long, spatulate, slightly indented in front end; no eyespots; nuchal organs present at between posterior end of prostomium and anterior end of peristomium ( Fig. 1A–B View FIGURE 1 ). Peristomium achaetous, as short as following rings. Mouth opening with striated lips; proboscis wide, lobed ( Fig. 1D View FIGURE 1 ).

Branchiae from chaetiger 6 onward ( Figs 1B View FIGURE 1 , 3A View FIGURE 3 ), lanceolate, densely ciliated ( Fig. 1E–F View FIGURE 1 ); first branchiae approximately ⅓ size of abdominal branchiae. Dorsal sensory organs present from chaetiger 12 ( Figs 1B View FIGURE 1 , 2B–C View FIGURE 2 , 3B View FIGURE 3 ), multiple per segment, oval-shaped; most anterior grouped ten per side forming one row, increasing to two on posterior thoracic segments, almost crossing midline; abdominal sensory organs forming two distinct groups irregularly disposed, reduced in number (four to five). Dorsal crest represented by a straight, consistent, flat curve, low and ciliated ( Fig. 1F View FIGURE 1 ).

Thorax slightly depressed ( Fig. 1E View FIGURE 1 ), both fragments with 45 chaetigers (~3 transitional segments with intermediate characteristics between thoracic and abdominal segments) ( Fig. 1B–C View FIGURE 1 ). Parapodia biramous. Thoracic notopodial postchaetal lobes slightly constricted, lanceolate, with elongated tips ( Figs 1E View FIGURE 1 , 2D View FIGURE 2 ). Thoracic neuropodial postchaetal lobes represented by a flange with an upper papilla, subtriangular ( Figs 1C, E View FIGURE 1 , 2A, D View FIGURE 2 ). Abdominal notopodia with postchaetal lobes hardly constricted, pyriform. Abdominal neuropodial lobes are represented by a flange with a triangular lobe, shorter than thoracic ( Figs 1F–G View FIGURE 1 , 2E View FIGURE 2 ).

Thoracic notochaetae with 20–25 crenulate capillaries in two bundles ( Fig. 2D View FIGURE 2 ). Abdominal notochaetae with about 20 capillaries and a few furcate chaetae each with unequal tines ( Fig. 2E View FIGURE 2 ). 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 ( Figs 2D View FIGURE 2 , 3C View FIGURE 3 ). Abdominal neurochaetae include three acicular spines ( Fig. 3D View FIGURE 3 ) and 5–8 crenulate capillaries intermixed ( Fig. 2E View FIGURE 2 ).

Pygidium unknown.

Remarks: Naineris bicornis is mainly distinguished by its slightly indented prostomium. Nevertheless, care is required when using the shape of the prostomium as the main diagnostic character. The shape of the prostomium is as it appears in the holotype is only seen occasionally and tends to be spatulate in specimens from other collections, probably due to fixation ( Figs 2A View FIGURE 2 , 3A View FIGURE 3 ).

Paired, dark segmental spots at bases of branchiae were not observed in the holotype but were present in chaetigers 5–6 in the additional specimens examined from the type locality or vicinity. They seem to correspond to internal structures that are transparent through the epidermis and must not be confused with the dorsal sensory organs ( Fig. 2A–B View FIGURE 2 ). These dark, segmental spots were also present in the juveniles of N. australis , the most similar species (see Zhadan et al. 2015, fig. 12D). In addition, dorsal sensory organs were not originally described in N. bicornis . As in N. australis , they are multiple ( Figs 2B–C View FIGURE 2 , 3B View FIGURE 3 ) and difficult to see in old, preserved specimens.

The chaetal arrangements of the thoracic neuropodia of N. bicornis , N. australis , and N. elegans sp. nov. are all similar. It includes the subuluncini, crenulate capillaries, and hooded uncini. The characters distinguishing N. bicornis from other similar species is based mainly on the features of thoracic notopodial lobes, distribution of multiple dorsal organs, geographic distribution and bathymetry. Thoracic notopodial lobes may be acute-to-rounded-tipped and possess a constriction in the middle, as in N. bicornis . Likewise, dorsal organs they may be grouped in rows or be irregularly distributed and may cross the midline depending on the species. Concerning their distribution, Naineris bicornis is distributed mostly in the Tropical Atlantic, whereas the other species are from the Pacific. Finally, N. bicornis occurs at continental shelf depths, whereas the other similar species are intertidal.

Recent molecular data have shown that N. bicornis is a species complex, and at least two species occur in Brazil (RA unpublished data). Molecular characterization of specimens from the type locality and Brazilian records of N. bicornis are necessary, but they are outside the scope of this study. This species was recorded only once in Brazil ( Nonato 1981) and was not abundant in the area ( Amaral et al. 2022). Recent sampling along the Brazilian coast resulted in two specimens, which were similar to N. bicornis , but with consistent molecular differences between them (RA unpublished data).

We also examined the holotype of Naineris bicornis minuta Hartmann-Schröder, 1965 (ZMH P-14869, type locality: Oahu, Hawaii). Because of the juvenile morphology of the holotype, it was impossible to find any morphological differences with N. bicornis . Further studies covering different oceans are necessary to clarify the species remaining in this group.

Distribution. Warm Temperate Northwest Atlantic province: Northern Gulf of Mexico ecoregion and Tropical Northwestern Atlantic province: Floridian and Southern Gulf of Mexico ecoregions, 11– 54 m.