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Lectotype lodged with the Museum für Naturkunde, Berlin (ZMB Bra 956), see specimens examined.
Synonymy
Magasella jaffaensis Blochmann, 1910
Campages jaffaensis Hedley, 1911
Diagnosis: A dallinid with ovoid to circular outline, rectimarginate–lightly sulcate anterior commissure, subpentagonal myophore atop large anteriorly supported cardinal process, thick crural bases, V-shaped septalium, trabecular loop, and large hinge teeth with thickened bases and lacking dental plates.
Etymology: Both genus name and specific epithet are derived from the Type location, Cape Jaffa, South Australia, the Latin suffix ‘-ensis’ added to form an adjective (i.e., from Cape Jaffa).
Description
Overall valve form: Maximum valve length 23.4 mm (average 17.8 mm, SD 3.9, smallest 8.5 mm long). Valves wide, W%L index averaging 89.9% (SD 4.3; range 80.6%–97.6%), and relatively thin with thickness index T%L averaging 46.8% (SD 3.5; range 39.5%−54.8%).
Overall outline (viewed dorso-ventral) ovoid on smaller specimens to almost circular on larger specimens (Fig. 7 A, B). Laterally biconvex (valves near equal in depth). Lateral commissure near flat or gently curved towards ventral valve (see Fig. 7 C–E). Anterior commissure near rectimarginate in small and large specimens (Fig 7 F), but showing progressing degrees of being lightly sulcate in some specimens, the dorsal (brachial) valve bearing a very shallow median groove in its anterior half, the anterior edge curved ventrally into a low median ridge on the anterior half of the ventral (pedicle) valve (Fig. 7 G). The Lectotype specimen is comparable to the above, it being near circular in outline, with flat lateral commissure, and rectimarginate anterior commissure (Fig. 8 A–D).
Valves punctate. With distinct concentric growth striae, smooth on most specimens but becoming more pronounced and thickened (ridge-like) on older specimens. Radial ribs/costae absent. Colouration of valves cream or beige, one specimen with pink pigmentation (E21970) was possibly from pigmented animals it was stored with.
Dorsal (brachial) valve: Cardinal margin obtuse (~115–140°). Cardinal process well-developed, the myophore a roughly pentagonal platform (though more rounded-off and circular on some speicmens), angled posteriorly, with small lateral swellings, supported anteriorly by triangular ridge originating between inner hinge plates and rising posteriorly (see Cardinalia ventral aspect in Fig. 7 H–K). Sockets well demarcated by outer and inner socket ridges, inner socket ridges lightly inclined and thicker and larger distally. Outer hinge plates narrow (poorly defined), inclined less than the inner socket ridges. Crural bases notably large and wide, dividing outer and inner plates (and laterally converging with inner socket ridges). Inner hinge plates inclined more steeply than outer plates, meeting medially as an excavate septalium, supported by median septum. Anterior edge of septalium V-shaped, septalium short and not extending anteriorly beyond crural base. Crura short and sub-parallel. Crural processes short, pointed, angled medio-ventrally (ventral and semi-lateral aspects of crural processes Fig. 7 H, K, J). Crura proportionally larger relative to the cardinalia on smaller specimens. Brachidium trabecular (Fig. 7 I–L), anterior-most extent of loop ~60%−70% dorsal valve length (loop proportionally longer in larger specimens, e.g., Fig. 7 I, J, and shorter in smaller specimens, Fig. 7 K). Median septum reducing in height anterior to septalium before rising to highest point at junction with brachial loop lateral connecting bands, then immediately reducing in height, terminating ~40%−50% dorsal valve length (see septum depicted in Fig. 7 I, J).
Ventral (pedicle) valve: Beak short (length approximately 8.5%−11% of overall valve length, proportionally smaller on larger specimens and vice versa), suberect. Foramen subapical (anterior to apex of beak), rounded and very small, but proportionally larger on smaller specimens and vice versa (diameter ~3%–5% of valve length), mesothyridid (closer to permesothyridid on some larger specimens), with beak ridges obscure and rounded (Fig. 7 M; Supplementary Fig. 1 D). Pedicle collar short. Deltidial plates mostly exposed, conjunct as a wide symphytium. Smaller individuals retain an irregular seam where the plates contact medially (Fig. 7 M), obscure on larger specimens but a thickened medial process remains on the inside face of the symphytium (Fig. 7 N–P). Hinge teeth large relative to symphytium, roughly triangular in outline, tooth bases swollen, proportionally larger on smaller specimens (see various aspects of teeth Fig. 7 M–P). Dental plates absent.
Soft tissue: Lophophore plectolophous. Gonads first noted on a specimen 12.7 mm long (E21970), distributed in four gonad lobes (2 on each valve), on the ventral valve the gonads are longer and each lobe V-shaped, on dorsal valve the lobes are shorter and straight. Gonads were either thin (Fig. 8 F, G) or greatly thickened (Fig. 8 H, I), presumably reflecting states of ripeness (though males and females were not distinguishable). Pedicle very short, not extending beyond beak (end papillate/rough).
Attachment substrata and epibiota: Attachment substrata for the pedicle were generally small fragments of dead shells (often gastropods), coral, and bryozoans. Regarding epibiota, < 20% of J. jaffaensis specimens examined had encrusting bryozoans growing on the valves.
Specimens examined
Lectotype. Off Cape Jaffa, South Australia, 165 m, ZMB Bra 956.
Paralectotype. Off Cape Jaffa, South Australia, 165 m, ZMB Bra 957 (dorsal valve missing).
Other material examined. ~40 specimens, southern Tasmania, 44.091°S, 146.698°E, 541 m, IN2018_V06 Stn 105, 8.xii.2018, TMAG E21968; 1 specimen, east Bass Strait, 38.92667°S, 148.46167°E [no depth], SS199405 Stn. 54, 27.viii.1994, TMAG E21970; 4 specimens, NE of Pedra Branca, southern Tasmania, 43.79°S, 147.62°E, 154 m, Stn UM 68.20, 9.i.1968, TMAG E21971 (two specimens used as dry preparations of internal structures, given new registration number E22187); 2 specimens, NE Bass Strait, 38.2149–2029°S, 149.6625–6974°E, 395–402 m, SS200001 Stn 150, 17.iv.2000, TMAG E22115; 1 specimen, Great Australian Bight, 33.2545–2644°S, 130.7058–808°E, 130–134 m, SS200001 Stn 351, 10.v.2000, TMAG E22116; 1 specimen, Great Australian Bight, 33.2471–2552°S, 130.6376−6159°E, 141 m, SS200001 Stn 334, 10.v.2000, TMAG E22117; 1 specimen, east Bass Strait, 38.955°S, 148.5083°E, 179–185 m, SS199305 Stn 54, 27.vii.1993, TMAG E22161; 3 specimens, NE Bass Strait, 38.1622–1677°S, 149.6987–6852°E, 260–265 m, SS200001 Stn 199, 22.iv.2000, TMAG E22162; 1 specimen, southern Tasmania, 43.2626°S, 147.9664°E, 122 m, Rambler Stn 68, 20.iii.2014, TMAG E29043a; 14 specimens, southern Tasmania, 44.0417–0489°S, 146.3116–3071°E, 410–450 m, SS200702 Stn 32, 4.iv.2007, TMAG E55892. 5 specimens, eastern Tasmania, 42.7000–6333°S, 148.4000–4167°E, 450 m, SO3/84 Stn 78, 25.vi.1984, TMAG E22219.
Remarks
In 1906 Professor Friedrich J.W. Blochmann, at the University of Tübingen (Germany), loaned brachiopod material from the Adelaide Museum (now South Australian Museum) and described Magasella jaffaensis. Out of the three specimens examined by Blochmann, none was designated the Holotype, and some parts have gone missing, and so Lüter & Sieben (2005) re-assessed the type series to designate a Lectotype and Paralectotype at the Museum für Naturkunde (Berlin). Charles Hedley (1911) provided some additional illustrations of the brachial loop of this species (as it was damaged in the Type material) and recognized its similarity to Campages, but otherwise did not describe it.
The work herein clarifies the morphology of Jaffaia and confirms (amongst other detail) the form of the hinge teeth, absence of dental plates, the complex form of the cardinal process, and provides detail on how the beak shape and anterior commissure folding change on larger specimens.
When sorting specimens, some previous misidentifications had been made with juvenile Magellania flavescens (Lamarck, 1819) and Anakinetica cumingi (Davidson, 1852), these species may look superficially similar and should be expected when working on old specimen lots. Juveniles of the former can easily be identified by the presence of radial ribs (though these can be faint), while the latter has a much straighter cardinal margin, and proportionally longer and straighter beak.
Distribution: Specimens examined herein were collected from the outer continental shelf and upper slope of the eastern and north-eastern Bass Strait, off Southern Tasmania, and the Great Australian Bight (33.25−44.09°S, 130.63−149.7°E), at depths ranging from 122–541 m. This was within the distributional and bathymetric ranges recorded Richardson (1997), southern, eastern, and western Australian coasts, 67–550 m.