Ernst et al.—Mississippian bryozoans of New Mexico
Table 6. Descriptive statistics of Clausotrypa denticulata (Ulrich, 1888) (16 colonies). Measurements and abbreviations as in Table 1.
Branch width Exozone width Endozone width Aperture width
Aperture spacing along branch 3 0.45 0.055 12.15 0.40 0.51 Aperture spacing diagonally Acanthostyle diameter Tectitozooecia width
16 0.18 0.060 33.31 0.12 0.32 16 0.38 0.110 28.76 0.20 0.62 19 0.10 0.009 8.82 0.08 0.12
6 0.29 0.045 15.35 0.25 0.37 29 0.04 0.011 29.19 0.02 0.07 32 0.04 0.014 31.25 0.02 0.08
N X SD CV MIN MAX 16 0.74 0.198 26.60 0.50 1.26
589
Autozooecia arranged in two rows on branches, triangular to trapezoidal in midtangential section. Axial wall between auto- zooecial rows strongly zigzag. Superior hemisepta present; inferior hemisepta absent. Keel broad, low, carrying two alter- nating rows of nodes. Dorsal surface containing microstylets and nodes (modified after Morozova, 2001, p. 57).
Occurrence.—Middle Devonian–upper Permian; worldwide.
Clausotrypa denticulata (Ulrich, 1888) new combination Figure 7.6–7.10; Table 6
1888 Streblotrypa (?Lioclema) denticulata Ulrich, p. 88, pl. 14, figs. 18, 19.
Syntype.—USNM PAL 43484, Waverly Group, Mississippian; Richfield, Ohio, USA.
Occurrence.—Andrecito Member, Lake Valley Formation, Mississippian (Osagean); Sierra County, New Mexico, USA (present paper). Cuyahoga shales, Wavery series, Mississippian; Ohio, USA.
Description.—Cylindrical branches, 0.50–1.26mmin diameter, with 0.12–0.32mm wide endozone and 0.20–0.62mm wide exozones. Autozooecia long, cylindrical, budding parallel to branch axis for long distance, gently curving toward colony surface. Autozooecial apertures oval. Thin, planar diaphragms rare in autozooecia. Tectitozooecia abundant, separating auto- zooecia in 1 or 2 rows, restricted to exozone, covered by thick calcitic skeleton on colony surface. Acanthostyles large, having distinct hyaline cores, 5–8 surrounding each aperture, arranged irregularly in spaces between autozooecia. Autozooecial walls laminated, having dark serrated boundaries, 0.008–0.010mm thick in endozones.
Materials.—NMMNHP-79583, P-79585 to P-79588, P-79610, P-79611, P-79613, and P-79615.
Remarks.—Clausotrypa denticulata is similar to C. ramosa (Owen, 1973) from the Mississippian of Europe, but differs from the latter in having thinner branches (branch diameter 0.50–1.08mm vs. 1.01–1.64mm in C. ramosa) and smaller autozooecial apertures (average aperture width 0.10mm vs. 0.13mm in C. ramosa).
Order Fenestrata Elias and Condra, 1957
Suborder Fenestellina Astrova and Morozova, 1956 Family Fenestellidae King, 1849
Genus Minilya Crockford, 1944
Type species.—Minilya duplaris Crockford, 1944, by original designation. Lower Permian; Australia.
Diagnosis.—Reticulate colonies consisting of moderately thick branches and thin dissepiments. Fenestrules almost rectangular.
Remarks.—Minilya is similar to Spinofenestella Termier and Termier, 1971, but differs in having two rows on the keel instead of one in Spinofenestella.
Minilya sp. Figure 8.1, 8.2; Table 7
Occurrence.—Tierra Blanca Member, Lake Valley Formation, Mississippian (Osagean); Sierra County, New Mexico, USA.
Description (exterior).—Reticulate colonies with straight bran- ches, joined by narrow dissepiments. Autozooecia arranged in two alternating rows on branches. Apertures circular, having low peristomes, 2 or 3 spaced per fenestrule length. Shape of fenestrules varying from oval to rectangular with rounded cor- ners. Keel low, carrying two alternating rows of small, closely spaced nodes. Internal granular skeleton thin, continuous with obverse keel, nodes, peristome, and across dissepiments. Outer lamellar skeleton thin. Reverse side smooth, containing micro- styles 0.010–0.015mm in diameter.
Description (interior).—Autozooecia triangular to trapezoidal in middle tangential section, low and elongated, with well- developed vestibule; aperture positioned distal to distal-abaxial end of chamber. Axial wall between autozooecial rows strongly zigzag. Superior hemisepta well-developed, serrated; inferior hemisepta absent.
Materials.—NMMNH P-79598 and P-79599.
Remarks.—Two species regarded as belonging to Minilya were described from the Mississippian of Utah: M. incipiens (Burkle, 1960) and M. crockfordae (Burkle, 1960). These species were only described externally, therefore their assignment to Minilya can be considered as uncertain. They each differ from the present material in having smaller-sized fenestrules and thicker branches. The present material differs from M. sivonella Snyder, 1991 from the Mississippian of the Upper Mississippi Valley in its smaller fenestrules (fenestrule length 0.67mmvs. 0.87mmin M. sivonella; fenestrule width 0.25mmvs. 0.33 in M. sivonella) and in spacing of 2 or 3 apertures per fenestrule length instead of 2–5in M. sivonella.
Genus Laxifenestella Morozova, 1974
Type species.—Fenestella sarytshevae Schulga-Nesterenko, 1951, by subsequent designation (Morozova, 1974). Mis- sissippian, Serpukhovian; Moscow Syncline, Russia.
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