Microporella tanyae Martino & Taylor & Gordon 2020, sp. nov.

Microporella tanyae sp. nov.

urn:lsid:zoobank.org:act: 324E8E55-E5FC-489A-843E-322D7F3A4FAB

Figs 2–3; Table 2

Colony erect, bifoliate; branches broad. Autozooids rhomboidal. Frontal shield granular, sparsely pseudoporous. Orifice transVersely D-shaped; hingeline straight, smooth; oral spines lacking. Ascopore elliptical, opening crescentic with projecting tongue and radial spines. Avicularium single, placed level with ascopore, oriented distolaterally; crossbar complete; opesia semielliptical; rostrum channelled. Ovicells not personate.

Named after Dr Tanya Knowles who collected the specimens in 2006.

Holotype

USA • Virginia, Chuckatuck; 2006; Tanya Knowles leg.; Pliocene; Upper Yorktown Formation; NHMUK PI BZ 8890 (Fig. 3).

Other material

USA • 1 specimen; Virginia, lower York County, Krause Pit; Edgar Campbell Col.; Pliocene; Yorktown Formation; USNM 387373 (Fig. 2).

COLONY. Starting with an encrusting unilaminar and multiserial base, later becoming erect with bifoliate fronds up to several cm wide; interzooidal communication not observed.

AUTOZOOIDS. Distinct, separated by narrow grooVes, rhomboidal, longer than wide (mean L/W = 1.39). Frontal shield moderately conVex, finely and densely granular; marginal areolae typically numbering about 10 (8–12), Variable in size (15–60 µm), funnel-shaped, sometimes subdiVided internally; up to about eight non-marginal pseudopores, morphologically very similar to areolar pores, generally placed more centrally on the frontal shield at the same level as the avicularium or slightly below, irregularly spaced, sometimes internally subdivided.

PRIMARY ORIfICE. Terminal, transversely D-shaped, widest medially, hingeline straight, smooth, without teeth or condyles; oral spines lacking; no peristome.

ASCOPORE fIELD. A narrow, raised area of gymnocystal calcification beneath leVel of adjacent frontal shield but at approximately same leVel as orifice, located Very close to its hingeline; elliptical, ca 30–

35 × 50–60 µm, distal margin with projecting, semielliptical tongue leaVing a crescent-shaped opening, ca 5–10 × 25–35 µm, with radial spines.

AVICULARIUM. Single, located between level of ascopore and lateral corner of rhomboidal autozooid, oriented laterally to slightly distolaterally; crossbar complete; opesia semielliptical; rostrum subtriangular, channelled.

OVICELL. Prominent, circular in outline, not personate and not obscuring orifice; calcification similar to frontal shield, impinging on aVicularium of distal autozooid; pseudopores Variable in number, confined to marginal areas.

This extinct species was found in the Pliocene of Virginia. Although very similar to the Miocene Microporella bifoliata, the new Pliocene species shows slightly shorter but wider, and consequently squatter, autozooids with larger orifices, larger aVicularia and broader oVicells. Additionally, the rostrum in M. tanyae sp. nov. narrows distinctly immediately distal to the crossbar, which does not seem to be the case in M. bifoliata specimens, and the orifice seems to be more clearly D-shaped with the proximal margin somewhat straighter.