Spinograptus Bouček and Münch, 1952

Kozłowska, Anna, Dobrowolska, Kinga & Bates, Denis E. B., 2013, A new type of colony in Silurian (upper Wenlock) retiolitid graptolite Spinograptus from Poland, Acta Palaeontologica Polonica 58 (1), pp. 85-92 : 88

Genus Spinograptus Bouček and Münch, 1952

Type species: Retiolites spinosus Wood, 1900 . Lectotype BU 1366, figured Wood 1900: pl. 25: 29A, selected and refigured Elles and Wood 1908: pl. 34: 16a ( Strachan 1971: 48). Lower Ludlow, Neodiversograptus nilssoni Biozone , West borderland, United Kingdom.

Species included.— Retiolites spinosus Wood, 1900 ; Retiolites clathrospinosus Eisenack, 1951 ; R. münchi Eisenack, 1951 ; Holoretiolites (Balticograptus) lawsoni Holland, Rickards, and Warren, 1969; Agastograptus quadratus Lenz, 1993 ; Spinograptus reticulolawsoni Kozłowska−Dawidziuk, 1997 ; S. latespinosus Kozłowska−Dawidziuk, 1997 ; S. praerobustus Lenz and Kozłowska−Dawidziuk, 2002 ; S. tubothecalis sp. nov.

Emended diagnosis (modified from Maletz 2010).—Nema free, exceptionally in two species attached distally, to obverse wall of short appendix; shallow ancora umbrella; outer ancora may be present; pre−thecal ventral orifices sometimes with paired processes, sometimes overgrown by reticulum; proximal lateral orifices above ancora umbrella medium sized; ventral wall formed of lip, genicular and lateral apertural lists; rudimentary mid−ventral lists and transverse rods sometimes present; ancora sleeve formed of oblique lists arranged in zigzag pattern; reticulum may be present on ventral and lateral walls; paired, reticulofusellar genicular processes. Rhabdosomes may be open−ended or finite with short appendices, the finite rhabdosomes may taper distally or exceptionally be parallel−sided with two distal isolated thecae with openings directed distally.

Remarks.—Our observations of the new species Spinograptus tubothecalis show a new character within Spinograptus , which is also unique among post Cyrtograptus lundgreni retiolitids: the nema attached distally to the obverse wall. This character is also possible in S. reticulolawsoni , but is not so clearly seen because of the presence of membranes in a flattened specimen ( Kozłowska−Dawidziuk 1997: fig. 10A, B). An outer ancora, not mentioned in Maletz‘s (2010) diagnosis, is present in three species: S. reticulolawsoni , S. clathrospinosus , and S. tubothecalis sp. nov. Maletz (2010) described parietal lists of the lateral walls often arranged in an irregular zigzag pattern, but in the referred material the zigzag pattern is rather regular.