Hemitrypa lasutkiniae Waschurova, 1964

Ernst, Andrej, Fernández, Luis Pedro, Fernández-Martínez, Esperanza & Vera, Carmen, 2012, Description of a bryozoan fauna from mud mounds of the Lebanza Formation (Lower Devonian) in the Arauz area (Pisuerga-Carrión Province, Cantabrian Zone, NW Spain), Geodiversitas 34 (4), pp. 693-738 : 725

Hemitrypa lasutkiniae Waschurova, 1964 ( Figs 18D, E ; 19 A-F; Appendix)

Hemitrypa devonica Nekhoroshev subsp. lasutkiniae Waschurova, 1964: 85 , pl. 27, figs 3-5.

MATERIAL. — SMF 21.333- SMF 21.360.

OCCURRENCE. — Lower Devonian (?Emsian); Tajikistan. Lebanza Formation, Lower Devonian (Pragian); Arauz Sur (Arroyo section), Palencia, NW-Spain (Cantabrian Mountains).

DESCRIPTION

Reticulate colonies with straight branches joined by dissepiments. Autozooecia arranged in two alternating rows on branches, having circular apertures with low peristomes, two spaced per length of a fenestrule. Peristomes smooth. Fenestrules oval to rectangular, varying in size. Openings in the superstructure irregularly shaped, rounded to petaloid, corresponding to positions of apertures, 0.10-0.14 mm in diameter. Superstructure containing small styles, 0.010 -0.015 mm in diameter. Internal granular skeleton continuous with obverse keel, nodes, peristome and across dissepiments, 0.02- 0.04 mm thick on the branch reverse wall. Outer lamellar skeleton well developed, 0.035 -0.050 mm thick on the branch reverse wall. Reverse colony surface containing large, irregularly sized nodes, 0.030 -0.075 mm in diameter. Heterozooecia not observed.

Interior description

Autozooecia triangular to trapezoidal or pentagonal in mid tangential section; low and elongated, with short vestibule in longitudinal section, diverging laterally at angles of 42-70°. Axial wall between autozooecial rows zigzag in tangential sections; aperture positioned at distal end of chamber. Hemisepta absent.

COMPARISON

The present material is similar to Hemitrypa lasutkiniae Waschurova, 1964 from the Lower Devonian (?Emsian) of Tajikistan, in having large nodes on the reverse side, the shape of the autozooecia and the size of the elements of the meshwork. Hemitrypa lasutkinae is similar to H. kulalica Waschurova, 1964 ( Waschurova 1964: 83, 84, pl. 6, fig. 4) in general morphology and the presence of nodes on the reverse surface, but differs in having slightly larger fenestrules and smaller openings of the protecting superstructure (0.10-0.14 mm vs 0.17 mm in H. kulalica ). Furthermore, Hemitrypa lasutkinae is similar to H. favosa Hall, 1881 from the upper Helderberg Group (Lower Devonian, Emsian) of Canada, but differs from the latter in the presence of nodes on the reverse side. The internal morphology of H. favosa is not known.

Figures

FIG. 18. — A-C, Rectifenestella exiliformis n. sp.; A, longitudinal section showing autozooecia and massive nodes, paratype SMF 21.331; B, branch transverse section showing autozooecia, paratype SMF 21.327; C, longitudinal section showing autozooecial chambers, internal granular and outer laminated skeleton, paratype SMF 21.319; D, E, Hemitrypa lasutkiniae Waschurova, 1964; D, branch transverse section showing branches and superstructure, SMF 21.353; E, branch transverse section, SMF 21.352. Scale bars: A, 0.5 mm; B, C, 0.2 mm; D, E, 1 mm.

FIG.19.— A-F, Hemitrypa lasutkiniae Waschurova,1964;A, B, oblique tangential section showing protecting superstructure and nodes on the reverse surface,SMF 21.355;C,D, tangential section showing autozooecial chambers,SMF 21.358;E, tangential section of reverse side showing nodes, SMF 21.357; F, openings in superstructure, tangential section, SMF 21.358; G, H, Tectulipora tuberculata n. sp., branch transverse section showing branches and superstructure, paratype SMF 21.380. Scale bars: A, C, H, 1 mm; B, G, 0.5 mm; D-F, 0.2 mm.