Bull. not. Hist. Mils. Land. (Geol.) 57(2): 109-1 14 



KX^3V<^6ZC,.0 



Issued 29 November 2001 



Systematic affinity of Acroporella assurbanipali 

 Elliott (Dasycladaceae), with notes on the 

 genus Neomeris 



FILIPPO BARATTOLO & ROBERTA ROMANO 



Dipariimento di Scienze dellci Terra, Universita degli Stiidi dl Napoli Federico II, Liirgo San MarceUino 10, 

 80138 Napoli, Italy 



Synopsis. The holotype of the extinct Dasycladacean alga Acroporella assurbanipali Elliott is re-described and a reconstruc- 

 tion is presented. The status of the species is reviewed, and it is assigned to the genus Neomeris, subgenus Larvaria. 



INTRODUCTION 



This paper deals with the systematic affinity of the Lower Creta- 

 ceous algaAcroporella assurbanipali. which is known only from the 

 type-locality at Erbil Liwa. Iran. We present a new description based 

 on a reinterpretation of the holotype, which is deposited in the 

 Natural History Musem, London (Elliott collection). A. assurbanipali 

 is reassigned to the genus Neomeris, subgenus Lan'aria. The taxo- 

 nomic status oi Acroporella and Neomeris is also discussed. 



ACROPORELLA ASSURBANIPALI AND ITS 

 RELATIONSHIP WITH THE GENUS 

 ACROPORELLA (PRATURLON) EMEND. 

 PRATURLON & RADOICIC 



The genus Acroporella was established by Praturlon in 1964 and 

 based on algal specimens from Upper Jurassic - Lower Cretaceous 

 shelf limestones of the Central Apennines (Marsica, Central Italy). 

 In that paper, Praturlon characterized the genus as simple thallus, 

 with euspondyle and acrophorous primary laterals (= branches), and 

 probably endosporous. The type species Acroporella radoicici has 

 the following characters: cylindrical, not segmented dasycladaceae; 

 branches acrophorous, simple, oblique to axis (15^5° on the hori- 

 zontal), arranged in euspondyle alternating whorls; calcification 

 reaching the axial cell; dimensions in mm (between brackets the 

 extreme value): D=0.55 (0.36-0.70); d=0.25 (0,17-0.33); p=0.06 

 (0.05-0.07); w=8-12; h=0.1 (0.085-0.11); maximum measured 

 length of the fragments=5.4; reproductive organs unknown. 



Praturlon & Radoicic (1974), following the rules of the Inter- 

 national Code of Botanical Nomenclature, changed the epithet from 

 A. raidoicici to A. radoicicae. Moreover, on the basis of better 

 preserved Barremian-Aptian material from Dinarides, they showed 

 that the species bears four short secondary laterals per primary 

 lateral set distally. Accordingly they proposed an emendation of the 

 genus and gave the following diagnosis iov Acroporella: 'Cylindri- 

 cal, not segmented dasycladaceae, having whorls of primary branches 

 distally ramified in clusters of button-like secondary twigs'. 



However six years before the emendation by Praturlon & Radoicic 

 ( 1974), Elliott had established the species A. assurbanipali from the 

 Lower Cretaceus of Erbil Liwa, Iran. According to Elliott ( 1968) the 

 species is characterised by: 'Cylindrical tubular calcified dasyclad, 

 external diameter 1.36 mm, internal diameter 0.55 mm (40% of 

 external); successive near-horizontal verticils, probably 3 or 4 per 



mm of tube-length, of perhaps twelve radial branches each. The 

 single branches communicate with the stem cavity by a pore of about 

 0.052 mm diameter: they then swell out to a fig- or flask-shaped 

 cavity of 0. 1 82 mm maximum diameter, narrow to a slightly curved 

 tube of 0.078 mm diameter, and then at the outer surface flare out to 

 a shallow terminal diameter of 0.156 mm". 



Since its proposal, A. assurbanipali has been overlooked by most 

 authors. Granier & Deloffre (1993) re-assessed its taxonomic posi- 

 tion and confirmed the affinity v^'nhAcroporella, but with reservations. 

 One of the authors of the present paper (F. Barattolo) recently 

 examined the Elliott collecfion at the Natural History Museum, 

 London. Re-examination of the single specimen in thin section 

 (holotype) and Elliott's description, allows us to propose a new 

 interpretation of the anatomy of the alga. Accordingly, we assign the 

 species to the genus Neomeris. 



NEOMERIS (LAMOUROUX, 1816), ITS 

 SUBGENERA AND ALLIED GENERA 



The genus was defined on an extant species from Jamaica {Neomeris 

 dumetosa Lamouroux). 



The alga is characterised by a cylindrical thallus bearing whorls of 

 primary laterals. Each primary lateral bears at its outer end a single 

 ovoid ampulla together with two secondary laterals. The laterals, 

 usually those of secondary order, may produce a cortical layer (Valet, 

 1968; Berger & Kaever, 1992). 



Seven species are known to live in tropical and subtropical seas 

 where they populate protected microenvironments of the reef plat- 

 form (Valet, 1979), in moderately exposed environments (e.g. 

 Neomeris mucosa) and in tidal pools (e.g. Neomeris cokeri) (Taylor, 

 1972). According to Konishi & Epis ( 1962) a depth of 0-10 m and a 

 temperature of 15-20°C are their optimal environmental conditions. 



The main diagnostic characters utilised in botanical description of 

 specific rank in extant Neomeris are: shape of primary laterals; shape 

 of secondary laterals and their distal ends making a cortex or not; 

 shape of fertile ampulla and cyst; shape of the plug set at the 

 connection between primary laterals and ampulla; calcification 

 (Genot, 1980). 



In spite of its modest role in the modern marine environment, the 

 genus Neomeris is well represented in the fossil record, but incom- 

 plete calcification does not allow observation of some characters that 

 are useful for classification. The earliest occurrence of the genus 

 (Neomeris cretacea) is in the Albian of Orizaba (Mexico; Barattolo, 

 1987). 



) The Natural History Museum. 2001 



