Scoloplos texana Maciolek & Holland, 1978

Zhadan, Anna, 2020, Review of Orbiniidae (Annelida, Sedentaria) from Australia, Zootaxa 4860 (4), pp. 451-502 : 464

Scoloplos texana Maciolek & Holland, 1978

Figure 7

Scoloplos texana Maciolek & Holland, 1978: 162–163 , fig. 1–4.

Scoloplos (Scoloplos) texana: Granados-Barba & Solís-Weiss 1997: 468 .

Leodamas texana: Blake 2017: 50 , 55, 59.

Material examined. Australia: Queensland: Hinchinbrook channel sand flat, 14.10.1989, 18°20’S, 146°04’E, coll. S. Dittmann, AM W.43439, 1 specimen . USA: Texas, Corpus Christy Bay , 27°48’38”N, 97°20’17”W, August 1974, Sta.122-6, 4.8 m, USNM 52729 , holotype; Texas, Redfish Bay , 27°52’20”N, 97°07’03”W, Sta. 152-2, USNM 52734 , paratypes, 5 specimens .

Type locality. USA: Corpus Christy Bay, Texas, Gulf of Mexico .

Description. Specimen AM W.43439 incomplete, thoracic width 2.2 mm. Thorax inflated in anterior part, slightly flattened in middle and posterior part ( Fig. 7A ). Prostomium conical with blunt tip ( Fig. 7A, C ). Thoracic chaetigers numbering 20, transition to abdomen sharp ( Fig. 7A, C ). Branchiae starting from chaetiger 21 (first abdominal), cylindrical with blunt tips, longer than notopodia ( Fig. 7 B–D, F). Thoracic notopodial postchaetal lobes developed from first chaetiger as rounded papillae, rapidly increasing in size along thorax, becoming oval with elongated tips; in abdomen foliaceous, shorter than branchiae ( Fig. 7C, D, F, G ). Thoracic neuropodial postchaetal lobes weakly developed, as low ridges without papillae ( Fig. 7A, B, E ). In abdomen, parapodia elongate, unilobed, almost rectangular with rounded tips ( Fig. 7B, D, F ). No subpodal, stomach, flange papillae, subpodal flange, or interramal cirrus present. Notopodial chaetae crenulate capillaries, in abdominal notopodia; forked chaetae present ( Fig. 7G ). Thoracic neurochaetae forming one row of few dark straight smooth non-hooded spines and bundle of 2–3 thin capillaries in upper part; abdominal neurochaetae thin capillaries ( Fig. 7A, B, E, F ). Both rami supported by aciculae in abdomen; notopodial aciculae much thicker than neuropodial, with long pointed projecting tips ( Fig. 7F, G ).

Distribution. West Atlantic (Gulf of Mexico, Caribbean Sea, Venezuela); Australia (?).

Habitat. Subtidal, clay, mud, muddy sand.

Remarks. Scoloplos texana was originally described from South Texas (Gulf of Mexico, USA) ( Maciolek & Holland, 1978). Later, it was redescribed from oil platform areas in the Gulf of Mexico (Granados-Barba & Solís- Weiss 1997). Scoloplos texana differs from a closely related species, Scoloplos treadwelli Eisig, 1914 , by having neuropodial spines arranged in one row, while in S. treadwelli they are more numerous and arranged in two rows in the anterior thorax. Other differing characters are the inflated thorax and blunt prostomium in S. texana versus the flattened thorax and pointed prostomium in S. treadwelli . In addition, the branchiae always start from the abdomen in S. texana but can start from the thorax or anterior abdomen in S. treadwelli (the presence of branchiae in the thorax was not found in the following studies: Granados-Barba & Solís -Weiss (1997) and Dean & Blake (2015)). Scoloplos texana was previously known only from tropical West Atlantic waters (Gulf of Mexico, Caribbean Sea, and Venezuela). The specimen found in Australia is similar to the type material specimens. This study is the first record of this species in Australian waters. This was likely an accidental introduction, since only the one specimen was found. It is not clear how it could have been imported into Queensland from West Atlantic. Orbiniids are rarely listed as invasive species; such examples are Proscoloplos cygnochaetus Day, 1954 (see below for details) and Naineris setosa ( Verrill, 1900) , described from Bermuda and later reported in the Mediterranean Sea ( Blake & Giangrande 2011; Khedhri et al. 2014).

Figures

FIGURE 7. Scoloplos texana, AM W.43439, A–D: stereomicroscope, methylene blue staining; E–G: compound microscope.A. Anterior part of the body, lateral view; B. Thorax-abdomen transition, lateral view; C. Anterior end, dorsal view; D. Abdomen, dorso-lateral view; E. Parapodium of chaetiger 9; F.Abdominal parapodium; G.Abdominal notopodium, note projecting acicula (a) and forked chaeta (fc). br, branchia; ne, neuropodium; no, notopodium.