Protoretepora irregularis, Ernst, 2016

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 46-48

Protoretepora irregularis n. sp.

Figures 20.5-7 , 21.1-5 ; Table 28

zoobank.org/ C6FD3035-7186-41C0-991C-0425C7478744

Etymology. The species is named after its irregular colony shape

Holotype. SMF 23.195 .

Paratypes. SMF 23.196 – SMF 23.204 , SMF 23.268 .

Type locality. Zhongba area of southwestern Tibet (E 84.31536, N 29.74233) .

Type stratum. Zhongba Formation, Permian (upper Cisuralian–Guadalupian).

Diagnosis. Irregular meshwork formed by broad branches; fenestrules large, irregularly oval to rectangular; autozooecia in 6–7 rows on branches; autozooecia rhombic in mid-tangential section; hemisepta absent; abundant microstyles arranged in rosette-like pattern; nodes spaced irregularly on the reverse colony surface; heteromorphs absent.

Exterior description. Reticulate colony formed by broad branches irregularly fused together; colony shape unknown. Fenestrules large, having irregularly oval to rectangular shape. Autozooecia arranged in 6–7 rows on branches. Autozooecial apertures circular, lacking peristomes. Keels absent. Nodes spaced irregularly on the reverse colony surface.

Interior description. Autozooecia rhombic in mid-tangential section, irregularly shaped at branch bifurcations; with well-developed vestibule protruding highly above the colony surface; elongate to branch length; aperture positioned at distal end of chamber. Hemisepta absent. Extrazooecial skeleton laminated, traversed by abundant microstyles. Microstyles 0.005 –0.015 mm in diameter, generally arranged in a rosette-like pattern. Heteromorphs not observed.

Remarks. Protoretepora irregularis n. sp. is distinct by its broad branches, irregular meshwork and presence of large nodes on the reverse colony surface. Protoretepora irregularis differs from P. robusta Bassler, 1929 from the Permian of Timor by having large and irregularly shaped fenestrules as well as large nodes on the reverse surface. Protoretepora irregularis differs from P. flexuosa Crockford, 1957 from the Lower Permian of Western Australia by the presence of 6–7 rows of autozooecia on branches instead of 4–5 rows in P. flexuosa . Furthermore, the new species has larger autozooecial apertures (average aperture width 0.18 mm vs. 0.13 mm in P. flexuosa ).

Figures

FIGURE 20. Thin section photographs of Mackinneyella obesa (Crockford, 1957), SMF 23.194 (1, 3), SMF 23.191 (2), and SMF 23.189 (4); and Protoretepora irregularis n. sp., paratype SMF 23.198 (5), SMF 23.268 (6), and SMF 23.195 (7). 1–3, and 7, tangential section showing autozooecial chambers; 4, branch transverse section; 5, branch longitudinal section; and 6, external view of the reverse side of the colony.

FIGURE 21. Thin section photographs of Protoretepora irregularis n. sp., paratype SMF 23.201 (1, 3, and 4), paratype SMF 23.202 (2), and holotype SMF 23.195 (5); and Tibetiporella ornata n. gen. n. sp., paratype SMF 23.224 (6 and 7) and holotype SMF 23.227 (8). 1, tangential section showing autozooecial apertures and chambers; 2, mid-tangential section showing autozooecial chambers; 3, 4, 7, and 8, tangential section showing autozooecial apertures, microstyles and nodes; 5, tangential section of obverse colony side with nodes; and 6, tangential section of the reverse side of the colony.