Rinistachya is a genus of Late Devonian sphenopsid, currently containing one species, Rinistachya hilleri.[1] It comprises the only sphenopsid as yet known from the Devonian of Gondwana, and is currently known from only a small number of specimens collected from the main fish layer/lens (MFL) black shale within the Witpoort Formation (Witteberg Formation, Cape Supergroup) at Waterloo Farm, Makhanda.[2] It is currently interpreted as a small-sized herbaceous plant.[1] and 'exhibits a novel architecture' that includes apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia).[2] Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales.[2] It is the only known high latitude sphenopsid known from the Devonian, the only other 3 genera, Eviostachya, Hamatophyton and Rotafolia being of palaeotropical provenance.[2]
The main stem is approximately 80 mm long and consists of a succession of nodes and internodes. From the examined material, the stem was characteristically slightly wider at the nodes and of the number of nodes observed, only one was well preserved. Internodes range from 0.9-1.2 mm in width with the longest being 40 mm. Fertile nodes are inserted in whorls of up to three axes at each node. These fertile nodes are between 0.4 to 0.5 mm in width. Each node has a whorl of leaves inserted together with a whorl of fertile parts. In well preserved parts of the specimens, fertile leaves are linear in shape and appear to be divided approximately two-thirds of their total length. Fertile leaves are weakly recurved on the inside of the leaves and are approximately 10 mm long.[2]
Etymologyedit
The genus name is derived from an isiXhosa name for the Makhanda city (former Grahamstown) while stáchya is a plural form of the Greek word “stáchys” referring to spikes. The species epithet hilleri is in honour of Professor Norton Hiller in recognition of his role as the original supervisor of Dr Gess’ excavations at Waterloo Farm.[2]
Referencesedit
^ abTAYLOR, T (2009), "Introduction to Paleobotany, How Fossil Plants are Formed", Biology and Evolution of Fossil Plants, Elsevier, pp. 1–42, doi:10.1016/b978-0-12-373972-8.00001-2, ISBN978-0-12-373972-8, retrieved 2021-06-21
^ abcdefPrestianni, Cyrille; Gess, Robert W. (2018-11-28). "Rinistachya hilleri gen. et sp. nov. (Sphenophyllales), from the upper Devonian of South Africa". Organisms Diversity & Evolution. 19 (1): 1–11. doi:10.1007/s13127-018-0385-3. ISSN 1439-6092. S2CID 53811583.
May 09, 2024
rinistachya, genus, late, devonian, sphenopsid, currently, containing, species, hilleri, comprises, only, sphenopsid, known, from, devonian, gondwana, currently, known, from, only, small, number, specimens, collected, from, main, fish, layer, lens, black, shal. Rinistachya is a genus of Late Devonian sphenopsid currently containing one species Rinistachya hilleri 1 It comprises the only sphenopsid as yet known from the Devonian of Gondwana and is currently known from only a small number of specimens collected from the main fish layer lens MFL black shale within the Witpoort Formation Witteberg Formation Cape Supergroup at Waterloo Farm Makhanda 2 It is currently interpreted as a small sized herbaceous plant 1 and exhibits a novel architecture that includes apparently plesiomorphic characters reminiscent of the organisation of the Iridopteridales including the production of two types of laterals at one node the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia 2 Other characters unambiguously nest Rinistachya within the Sphenopsida including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil This provides strong support for a close relationship between Sphenopsida and Iridopteridales 2 It is the only known high latitude sphenopsid known from the Devonian the only other 3 genera Eviostachya Hamatophyton and Rotafolia being of palaeotropical provenance 2 Rinistachya Specimen showing the whorl with preserved leaves Scientific classification Kingdom Plantae Clade Tracheophytes Division Polypodiophyta Class Polypodiopsida Subclass Equisetidae Order Sphenophyllales Genus RinistachyaPrestianni amp Gess 2019 Species R hilleri Binomial name Rinistachya hilleriPrestianni amp Gess 2019Description editThe main stem is approximately 80 mm long and consists of a succession of nodes and internodes From the examined material the stem was characteristically slightly wider at the nodes and of the number of nodes observed only one was well preserved Internodes range from 0 9 1 2 mm in width with the longest being 40 mm Fertile nodes are inserted in whorls of up to three axes at each node These fertile nodes are between 0 4 to 0 5 mm in width Each node has a whorl of leaves inserted together with a whorl of fertile parts In well preserved parts of the specimens fertile leaves are linear in shape and appear to be divided approximately two thirds of their total length Fertile leaves are weakly recurved on the inside of the leaves and are approximately 10 mm long 2 Etymology editThe genus name is derived from an isiXhosa name for the Makhanda city former Grahamstown while stachya is a plural form of the Greek word stachys referring to spikes The species epithet hilleri is in honour of Professor Norton Hiller in recognition of his role as the original supervisor of Dr Gess excavations at Waterloo Farm 2 References edit a b TAYLOR T 2009 Introduction to Paleobotany How Fossil Plants are Formed Biology and Evolution of Fossil Plants Elsevier pp 1 42 doi 10 1016 b978 0 12 373972 8 00001 2 ISBN 978 0 12 373972 8 retrieved 2021 06 21 a b c d e f Prestianni Cyrille Gess Robert W 2018 11 28 Rinistachya hilleri gen et sp nov Sphenophyllales from the upper Devonian of South Africa Organisms Diversity amp Evolution 19 1 1 11 doi 10 1007 s13127 018 0385 3 ISSN 1439 6092 S2CID 53811583 Retrieved from https en wikipedia org w index php title Rinistachya amp oldid 1080617919, wikipedia, wiki, book, books, library,
