Notaulax Tauber, 1879

Tovar-Hernandez, Maria Ana Ana, Garcia-Garza, Maria Elena & de Leon-Gonzalez, Jesus Angel, 2020, Sclerozoan and fouling sabellid worms (Annelida: Sabellidae) from Mexico with the establishment of two new species, Biodiversity Data Journal 8, pp. 57471-57471 : 57471

Notaulax Tauber, 1879

Notaulax Notaulax rectangulata Levinsen 1883

Notaulax Tauber, 1879 ( Tauber 1879): 136.

Notaulax .- Perkins 1984: 327, 329; Fitzhugh 1989: 75; Tovar-Hernández et al. 2017: 21; Capa et al. 2019: 197-198; Tovar-Hernández et al. 2020: 27-28.

Diagnosis

Radioles in semi-circular radiolar lobes, each radiole with at least four rows of vacuolated cells. Radiolar crown with elongate basal lobes; palmate membrane, radiolar flanges and dorsal and ventral basal flanges present. Numerous ocelli arranged in longitudinal rows on lateral sides of radioles. Dorsal lips with radiolar appendages, pinnular appendages absent; ventral radiolar appendages absent. Ventral lips and parallel lamellae present, ventral sacs inside radiolar crown. Anterior peristomial ring low, of even height, or high and rounded. Posterior peristomial ring collar with narrow mid-dorsal gap, dorsal margins laterally fused to the faecal groove, ventrally entire or with mid-ventral incision and short ventral lappets. Peristomial vascular loops absent. Peristomial eyespots absent. Thorax and abdomen with variable number of segments. Glandular ridge on chaetiger 2 absent. Ventral shields present. Interramal eyespots may be present. Collar chaetae spine-like, arranged in distally oblique longitudinal rows, diagonal, J or C-inverted shaped; superior thoracic notochaetae short spine-like, inferior thoracic notochaetae paleate. Thoracic uncini avicular, with several rows of minute and similar in size teeth above main fang, developed breast and medium-sized handle; neuropodial companion chaetae with strongly asymmetrical hood, stouter on one margin and thin, elongate tip. Abdominal uncini similar to the thoracic ones. Anterior abdomen with a superior group of elongate, narrowly-hooded chaetae and an inferior group of paleate chaetae with mucros. Posterior abdomen with modified, elongate, narrowly-hooded chaetae and paleate chaetae (spherical or oval) with long mucros. Pygidial eyespots may be present. Anal cirrus absent (after Tovar-Hernández et al. 2020).

Taxon discussion

Perkins (1984) revised the genus, described new species, provided several synonyms and proposed new combinations of species within Notaulax . Since then, Notaulax sp. 1, Notaulax sp. 2 and Notaulax sp. 3 have been reported from Lizard Island by Capa and Murray (2015). Notaulax yamasui Nishi et al. 2017 was established to Japan. Sabella tilosaula Schmarda, 1861 ( Schmarda 1861) was transferred to Notaulax and a new species was described from Puerto Deseado (Argentina) as Notaulax salazari by Tovar-Hernández et al. (2017). Lastly, the genus was amended by Tovar-Hernández et al. (2020) who also recognised three species from Indonesia within Notaulax : Sabella pyrrhogaster Grube, 1878 ( Grube 1878), Sabella (Potamilla) tenuitorques Grube, 1878 ( Grube 1878) and Notaulax montiporicola Tovar-Hernández and ten Hove, 2020 ( Tovar-Hernández et al. 2020). Despite these efforts, the genus is waiting for a worldwide revision as supported below.

The generic diagnosis by Fitzhugh (1989) stated that chaetae from the anterior abdomen are elongate, narrowly-hooded, whereas chaetae from the posterior abdomen are modified, elongate, narrowly-hooded chaetae. Then, the diagnosis provided by Capa et al. (2019) refers to the abdominal chaetae as needle-like without any differentiation between anterior and posterior abdomen. Needle-like chaetae sensu Fitzhugh (1989) [Fig. 24A] are straight capillaries present in some serpulids as Protula Risso, 1826 which are different from those present in Notaulax (slightly curved, thin, long and narrowly hooded). It is hard to obtain complete specimens since these are embedded within strong tubes in dead or living coral, rocks or as fouling. However, below we designated the holotype of N. nigrofouling sp. n., from the Gulf of California based in a complete specimen. We confirm that these abdominal chaetae are, in fact, narrowly hooded which usually become progressively longer towards the pygidium (where these are referred as modified, elongate, narrowly hooded).

As Tovar-Hernández et al. (2020) pointed out, chaetae from the anterior half of the abdomen are different from those in the posterior half of the abdomen in Notaulax . Chaetae from the anterior abdomen are paleate, nearly rounded or spherical with short mucros (as long as palea width), whereas chaetae from the posterior abdomen are spherical or oval, but with a long mucro, longer than three times the width of paleae. In Notaulax montiporicola , the presence of two types of mucros in the abdominal paleate chaetae is remarkable: with candle flame-shaped mucros in anterior abdominal segments, sail-shaped mucros posteriorly. This combination of abdominal chaetae has never been detected before in Notaulax , but it might be an important feature to distinguish genera. In Anamobaea , chaetae from the posterior abdomen are paleate, but with long mucros in contrast with those from the anterior abdominal segments in which the mucro is short (as long as palea width).

Chaetae from the collar have been called spine-like sensu Perkins (1984) or Fitzhugh (1989). Moore and Bush (1904) realised that, in Notaulax lyra (as Hypsicomus ), the collar chaetae are arranged in a double series along each line, but those spine-like chaetae are slightly different to each other. Spine-like chaetae of the dorsal-most series are stouter, nearly straight, terminated by an elongated conical hood or sheath more or less inflated at the base and usually bent or wavy in the slender distal half (see Moore and Bush 1904: plate XI, figure 8). Those of the ventral-most series are more slender, sharply curved at the end and provided on the convex side with a short but broad obliquely-striated wing (see Moore and Bush 1904: plate XI, figure 7). This differentiation could be useful to genera level since it has been unnoticed in most contributions.

Perkins (1984) recommended as characters of specific importance the arrangement and position of radiolar ocelli, the shape of collar, the number of thoracic chaetigers, the cross sectional structure of the radioles and pronounced differences in the chaetae and uncini. However, the number of thoracic chaetigers is variable due ontogeny. Assessing sections of radioles to count the number of skeletal cells and lengths of flanges is not practical at the specific level (it is informative and useful to genera level in some genera). First, these are impacted by anaesthetics and fixation methods. Second, the number of cells and flanged extension lengths will depend of where the sections are done (basally, where the basal lamina ends or in an intermediate zone where the palmate membrane is). Third, if sections are hand-made using scissors, razor blades or scalpel, often this procedure makes thick sections near to 1 mm width, in contrast with those assessed using a microtome were sections are in microns. Consequently, the number of cells can vary in some order of magnitude depending on the method to sectioning radioles and different interpretations by researchers.

Variability of some other features were emphasised by Perkins (1984). He remarked that the collar of some species change during development from a 4-lobed structure on juveniles to a 1 or 2 lobed structure on adults, which cannot be corroborated in this study. In many specimens of N. nigroincrustata sp. n., reviewed here (six types and 14 additional specimens), the ventral margin of the collar is always entire, but it has two variations: even in height (as lateral margins of collar) or slightly higher than lateral margins of collar; and the lateral collar margins can be even in height or asymmetrical V-shaped.

As stated by Perkins (1984), in juveniles, the position and organisation of ocelli are not diagnostic. It was also corroborated in N. californica where juveniles have five ocelli or up to 16 ocelli in adults (see below). In addition, the length of the basal lamina (or radiolar lobes) is also variable as demonstrated in this study by N. nigroincrustata sp. n.

Perkins (1984) also stated that minute mucros were sometimes observed on the concave side of the thoracic palea (to N. nudicollis see Perkins 1984 [figure 28E-F]). These were apparently not developed or were broken. In Nishi et al. (2017) [figure 3B-C], the thoracic palea analysed under a Scanning Electron Microscopy (SEM) showed a small scar on the top (not in the concave side of palea), but these went unnoticed or not mentioned. In this study, mucros or scars in the thoracic palea were not detected in Mexican specimens; perhaps, if present, these are only detectable under SEM. In contrast, possibly the length of the mucro of paleae from the anterior half of the abdomen might be useful for distinguishing species, as well as the shape of chaetae from the posterior half of the abdomen.