Pyura doppelgangera, Rius & Teske, 2013

Rius, Marc & Teske, Peter R., 2013, Cryptic diversity in coastal Australasia: a morphological and mitonuclear genetic analysis of habitat-forming sibling species, Zoological Journal of the Linnean Society 168 (3), pp. 597-611 : 601-604

PYURA DOPPELGANGERA SP. NOV.

Material examined: We examined specimens from a variety of locations ( Table 1) and a representative suite of these was deposited in the Iziko South African Museum (accession numbers: 25991 – Port Welshpool, 26008 holotype – Bridport, 26009 paratype – Bridport). Samples from the type locality (Bridport) were either used for morphological or genetic analyses ( Tables 1, 2) .

Description (holotype and paratype): The specimens (measured in contracted individuals) are 26 and 30 mm in maximum dorsal length, their height (measured from the base to the top of the siphonal area) 34 to 45 mm, and their width 18 to 20 mm. The specimens show a short peduncle that appears from the base. The tunic has sand embedded in it and has no pointed papillae ( Fig. 2D ). The tunic thickness is thin compared to other representatives of the P. stolonifera species complex. Siphonal spines are long and pointed and their bases are slightly expanded ( Fig. 1A ).

The body wall is orange, but dark purple around the siphons. The body size is 25 to 26 mm in length, 20 to 21 mm in height, and 12 to 15 mm in width. There are anterior longitudinal muscular bands across the body, with circular muscular bands around the siphons. There are 33 to 34 ramified oral tentacles of different sizes (alternating between large and small).

The branchial formula is: right side of the specimen, counting from the endostyle (RE) 3 (12) 1 (12) 2 (13) 3 (12) 2 (16) 2 (15) 2 dorsal lamina (DL) 3 (14) 2 (11) 2 (14) 2 (12) 2 (10) 2 (9) 5 left side, to the endostyle (EL) and RE 5 (11) 2 (10) 3 (10) 2 (14) 3 (12) 1 (15) 2 DL 3 (14) 2 (11) 3 (14) 2 (13) 2 (10) 2 (8) 3 EL. Branchial stigmata are straight and between 9 and 11 are present per mesh. The dorsal tubercle is arranged as a double spiral and is not granulated ( Fig. 2F ). The dorsal lamina is short and contains small languets ( Fig. 2G ). The dorsal tubercle shows a characteristic orientation in relation to the line delineated by the dorsal lamina. In this case it is between 40 and 80° to the left ( Fig. 2F, G ).

The right gonad show the same positioning as in other Australasian forms, forming two rows of lobes. The gonoduct of the right gonad opens 2–3 mm away from the gonad and is perpendicular to the vertical

*Some colour variation is expected owing to a different concentration of, and exposure time to, formalin.

†This quantitative character is positively correlated with body size in all species.

‡Counts are made from the endostyle on the right side of the body (RE) to the dorsal lamina (DL) and from the DL to the endostyle on the left side (EL).

position of the gonad. The left gonad is inside the gut loop and forms a single row of lobes ( Fig. 2G ). The gonoduct on the left side of the body opens 7–12 mm away from the first gonadic block and is located next to, but separated from, the anal aperture ( Fig. 2C ). The gut is located on the left side of the body and forms a sharply curved loop that is followed by an extremely short secondary loop just before the anus ( Fig. 2G ). The hepatic gland is large and branched and contains two bifurcated hepatic lobes. The anal border has fine edges and no lobes ( Fig. 2A, B ).

Morphological variation: The examination of P. doppelgangera specimens (see Table 1) revealed some morphological variation. The maximum dorsal length of the specimen (with tunic) is generally no larger than 55 mm, with the height ranging from 25 to 50 mm and the width from 15 to 35 mm. The tunic thickness is variable and can be as tough as that of other representatives of the P. stolonifera species complex, but some of the specimens examined had an extremely thin and flimsy tunic. Most individuals are aggregated in clumps and some show a short peduncle that appears from the base. The body wall is generally dark purple but it can be orange. The siphons are always dark violet, and there is normally a gradient of colours ranging from orange to purple around the siphons. The body size ranges from 23 to 45 mm in length, 15 to 32 mm in height, and 7 to 21 mm in width (as above, size of contracted specimens). There can be from 18 to 33 ramified oral tentacles (with more tentacles in larger individuals than in smaller ones). The branchial formula of the smallest individual found is: RE 5 (9) 2 (10) 2 (11) 2 (15) 2 (14) 1 (13) 2 DL 2 (14) 1 (12) 1 (14) 2 (13) 2 (11) 1 (10) 1 EL, and that of the largest individual is: RE 6 (12) 2 (12) 3 (14) 2 (16) 2 (12) 1 (17) 3 DL 3 (19) 2 (16) 2 (18) 3 (17) 2 (17) 2 (13) 4 EL. Branchial stigmata range from seven to 12 per mesh. The dorsal tubercle is always arranged as a double spiral and in most cases is not granulated. In the few individuals that show granulation, it is considerably less than in P. praeputialis . The dorsal lamina is short (containing small languets) or non-existent. The dorsal tubercle is between 20 and 90° to the left of the line delineated by the dorsal lamina, but in a few instances it is found 20° to the right. The gonoduct of the right gonad opens 1 to 6 mm away from the gonad, whereas the gonoduct on the left side of the body is longer (opening approximately 8–12 mm away from the first gonadic block).

Remarks: There are a number of distinctive internal characters that are unique to this species ( Fig. 2 ). The four main ones are: (1) the dorsal tubercle is smooth; (2) the anus has no defined lobes; (3) the digestive track does not have a secondary gut loop or it is short and never curves sharply; (4) the gonoduct on the left side is clearly separated from the anal aperture.

Distribution: This species has been found on lower intertidal shores along the entire Tasmanian coast and in northern New Zealand, and exclusively on artificial structures in Victoria and South Australia.

Etymology: The species is named P. doppelgangera after the German word ‘Doppelgänger’, which in its narrowest sense means look-alike (i.e. somebody who closely resembles somebody else). The ending ‘a’ is used to indicate a feminine noun in the nominative singular. The meaning of the name reflects the difficulty of distinguishing this species from P. praeputialis because of its similar morphology.

Figures

Figure 1. Scanning electron microscope photographs of the siphonal spines of the species comprising the Pyura stolonifera species complex. A, Pyura doppelgangera sp. nov., B, Pyura praeputialis, C, Pyura dalbyi, D, Pyura herdmani, E, P. stolonifera. Scale bars: A = 100 Mm; B, D = 40 Mm; C = 50 Mm; E = 10 Mm.

Figure 2. Pyura doppelgangera sp. nov. A, anal border (view from above); B, anal border (lateral view); C, gonoduct left side; D, an individual specimen collected in Tasmania. Photograph: Carmen Primo; E, the same individual without tunic. Photograph: Carmen Primo; F, dorsal tubercle and lamina with languets; G, internal structure detailing the position of the hepatic gland, dorsal tubercle, gonad on the right side of the body and the gut and gonad on the left side. Scale bars: A-C = 1 mm; D, E = 20 mm; F = 2 mm; G = 10 mm.