Naineris australis Hartman, 1957

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 : 401-403

Naineris australis Hartman, 1957

( Fig. 4 )

Naineris grubei australis Hartman, 1957: 303–304 , pl. 39, figs 1–4; 1959: 366.— Day 1977: 238.— Hutchings & Rainer 1979: 761.— Hutchings & Murray 1984: 53.— Zhadan et al. 2015: 793–797, figs 10A–G, 11A–C, 12D.

Naineris grubei .— Day 1977: 237–238.

Naineris australis .— Blake 2017: 103; Zhadan 2020: 479–480 , fig. 15A–E (in part).

Material examined. Australia, Queensland: off Casuarina Beach, Lizard Island, coll. K. Meissner and T. Alvestad, 14Aug 2013, 1 m, fine sand, 14.67944°S, 145.44703°E, intertidal, (1, AM W.44038); Heron Island, coll. G. Hartmann-Schröder, coral sand from residual ponds between coral colonies at the North Reef, probably intertidal, 02 Apr 1976 (1, ZMH P-21075). New South Wales: Broughton Island, coll. NSW Fisheries, 01 Sep 1976, Posidonia diving cores, 32.62°S, 152.32°E, intertidal, (1, AM W.13138); Botany Bay, Towra Point, coll. K. Robinson, Jul 1981, Zostera , sand/mud sediment, 34°S, 151.16°E, intertidal, (2, AM W.195061). South Australia: Port Noarlunga, Onkaparinga, Adelaide, Sta. 104a, coll. S. J. Edmonds, 35.150004°S, 138.466649 °E, intertidal, holotype of Naineris australis ( LACM-AHF Poly 676). Western Australia: Exmouth, Town Beach, coll. G. Hartmann-Schröder, 10 Oct 1975, ripple-marked flat, fine silt with little sand, probably intertidal, (5, ZMH P-16592).

Measurements. Holotype 48 mm long, 1.5 mm wide, for 173 chaetigers.

Diagnosis. Spatulate prostomium. Multiple dorsal sensory organs small, oval-shaped, 2–10 per side, grouped in a single longitudinal row throughout body; first segments a pair per side, increasing in number posteriorly, up to ten in abdominal segments, not crossing midline. Thoracic notopodial lobes digitiform. Thoracic neuropodial lobe with an upper tongue-like 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. Body long, with thorax and abdomen about the same width ( Fig. 4A ). Ventrally thorax smooth, but abdomen, tri-annulate with central ring wider than others.

Prostomium spatulate ( Fig. 4B ); eyespots absent; nuchal organs present at posterior end of prostomium and anterior end of peristomium ( Fig. 4B ). Peristomium with two achaetous rings, weakly delimited. Mouth opening with lips striated; proboscis only partially everted, represented by a lobe ( Fig. 4B ).

Branchiae from chaetiger 6 onwards; long, glandular, and ciliated ( Fig. 4C, D ); first digitiform, half size of abdominal branchiae, then increasing in size and a triangular shape. Abdominal branchiae longer, crossing midline, not reaching opposite branchial base. Multiple dorsal sensory organs per segment present from mid-thoracic chaetigers; small, oval-shaped, 2–10 per side, grouped in single longitudinal row throughout body; first segments one pair per side, increasing in number posteriorly, up to ten in abdominal segments ( Fig. 4F ), not crossing midline. Dorsal crest straight, consistent, flat, forming a low curve ( Fig. 4C, D ).

Thorax weakly depressed, with 38 chaetigers (~4 transitional segments with intermediate characteristics between thoracic and abdominal segments) ( Fig. 4A ). Parapodia biramous. Thoracic notopodial lobes digitiform ( Fig. 4B, C ). Thoracic neuropodial lobes represented by a flange with a tongue-like papillae on superior tip ( Fig. 4B, C ). Abdominal notopodial lobes cirriform ( Fig. 4D, G ). Abdominal neuropodial lobes triangular with a thin projection on tips ( Fig. 4D, G ).

Thoracic notochaetae: 20–30 crenulate capillaries in two bundles.Abdominal notochaetae: two groups of 10–20 crenulate capillaries. Thoracic neurochaetae: a transverse, anterior row of small capillaries, six transverse, posterior rows of numerous subuluncini; an inferior, posterior, oblique row of about 20 crenulate capillaries and an inferior, anterior, oblique row of about 20 hooded uncini ( Fig. 4E ). Abdominal neurochaetae: 3 acicular spines and 5–10 crenulate capillaries.

Pygidium unknown.

Variation: The number of thoracic chaetigers of the specimens studied ranged between 36–50, as in other species it is size-related. Dorsal sensory organs ranged from two to five pairs on posterior segments.

Remarks: Naineris australis was originally described as a subspecies of Naineris grubei ( Gravier, 1908) by Hartman (1957), redescribed by Zhadan et al. (2015) and was elevated to species rank by Blake (2017), based on differences in the structure of the thoracic neurochaetae and the presence of subuluncini in N. australis .

Dorsal sensory organs were not described for N. australis by Hartman (1957), but Zhadan et al. (2015), noted the presence of up to five pairs per segment in specimens from Lizard Island. After examining the holotype and other collections, we observed that they varied throughout the body. We stress that it is difficult to see multiple dorsal organs in preserved specimens, and they are usually visible as small transparent scars. It is necessary to use an appropriate light and contrast medium to facilitate its observation; explaining why often overlooked.

We examined some of the specimens examined by Zhadan (2020), and the voucher AM W.22470 (Fig. 15D, E) was misidentified, corresponding to a specimen of the N. setosa ( Verril, 1900) species complex, bearing only capillaries in thoracic neuropodia, and paired dorsal organs.

Distribution. Southwest Australian Shelf, Southeast Australian Shelf, East-Central Australian Shelf, and Northeast Australian Shelf provinces, intertidal.

Figures

FIGURE 4. Naineris australis. Holotype (LACM-AHF Poly 676). A, complete specimen; B, anterior end, lateral view; C, thoracic segments, dorsal view; D, abdominal segments, dorsal view. N. australis (ZMH P-16592). E, thoracic neurochaetae, lateral view. N. australis (AM W.195061). F, abdominal segments, dorsal view; G, abdominal postchaetal lobes. br—branchiae, cc—crenulate capillaries, dc—dorsal crest, do—dorsal organs, NeL—Neuropodial lobe, NoL—Notopodial lobe, no—nuchal organ, pb—proboscis, pr—prostomium, su—subuluncini, u—uncini (Scales: A: 1 mm; B–E, G: 0.5 mm; F: 0.2 mm).