Aramazdospirifer, Serobyan & Danelian & Crônier & Grigoryan & Mottequin, 2022

Serobyan, Vahram, Danelian, Taniel, Crônier, Catherine, Grigoryan, Araik & Mottequin, Bernard, 2022, Aramazdospirifer orbelianus (Abich, 1858) n. comb., a new cyrtospiriferid brachiopod genus and a biostratigraphically important species from the lower Famennian (Upper Devonian) of Armenia, Comptes Rendus Palevol 21 (6), pp. 145-156 : 148-150

Aramazdospirifer n. gen.

urn:lsid:zoobank.org:act:A0600124-6E54-4870-8F61-F487591F91CA

DIAGNOSIS. — Shell of medium-size, ventribiconvex, subpentagonal, wider than long to longer than wide, with mucronate cardinal extremities; generally widest at hinge line; ventral interarea moderately high, apsacline; delthyrium wide and most of its height covered by a pseudodeltidium, the latter is composed of several distinct plates, with submesothyrid foramen; fold and sulcus moderately wide, well-defined, median longitudinal elevation developed in sulcus and frequently on fold; ribs numerous, usually simple on flanks, increasing by bifurcation in sulcus and on fold; micro-ornament capillate both on ribs and in interspaces; dental plates long, strong and intrasinal; delthyrial plate well-developed; unsupported ctenophoridium with numerous vertical lamellae; crural plates short; dorsal myophragm present.

TYPE SPECIES. — Spirifer orbelianus Abich, 1858 .

OTHER SPECIES. — It is currently difficult to assign other species to Aramazdospirifer n. gen. with certainty in the absence of taxonomical revisions of the diverse cyrtospiriferide fauna from the Famennian of the ex-USSR. Spirifer (Cyrtospirifer) aperturatus von Schlotheim sensu Nalivkin (1930) described in the Central Kara-Tau and along the headwaters of the Naryn river ( Kazakhstan) likely belongs to the new genus, although the latter has a less globular shell, subcircular tongue and lacks median and longitudinal elevations in sulcus and fold. It is worth noting that the real aperturatus from Germany and the Franco-Belgian basin differs from Nalivkin’s species and does not belong to Aramazdospirifer n. gen. (see Paeckelmann 1942; Vandercammen 1959). It is also probable that Cyrtospirifer (Cyrtospirifer) pentagonalis Sidjachenko (1962) described from the Famennian of Central Kara-Tau should be assigned to Aramazdospirifer n. gen. as it shares many common features with the new genus. More precisely its inflated and subpentagonal shell that is ornamented with closely spaced and flattened ribs, acute to mucronate cardinal extremities and apsacline triangular ventral interarea that fit well with the diagnosis of the new genus. Nevertheless, the micro-ornament, the internal morphology and the type of pseudodeltidium of the latter species is unknown. Finally, Cyrtospirifer aquilinus Romanowski sensu Nalivkin (1930) described from the Central Kara-Tau and along the headwaters of the Naryn river ( Kazakhstan) might also be assigned to the new genus, although it lacks median and longitudinal elevations in sulcus and on fold. However, its micro-ornament and internal morphology is unknown. All these uncertainties preclude the possibility of a definite assignment to Aramazdospirifer n. gen.

ETYMOLOGY. — In honor of Aramazd, who was the chief god in pre-Christian Armenian mythology.

REMARKS

Aramazdospirifer n. gen. is included in the superfamily Cyrtospiriferoidea based on the presence of dental plates, a ctenophoridium, a well-developed delthyrial plate, and capillate ornamentation. Although a thorough revision of this superfamily, recommended byMa & Day (2000), is still pending, Aramazdospirifer n. gen. is assigned to the family Cyrtospiriferidae , as defined by Johnson (2006), due to the development of ribs in the sulcus and on fold. Additionally, its wide hinge line argues for its assignment to the subfamily Cyrtospiriferinae rather than to the Cyrtiopsinae.

Afanasjeva inAlekseeva et al. (2018a) examined some specimens collected from the Armenian sections and reassigned Abich’s species to the late Givetian? – early Frasnian genus Uchtospirifer Liashenko, 1957 known from South Timan ( Russia). Aramazdospirifer n. gen. shares indeed several external and internal characters with Uchtospirifer Liashenko, 1957 sensu Sokiran (2006) . More particularly, both genera display a subpentagonal shell that is ornamented with closely spaced and flattened ribs (also in sulcus and on fold), an apsacline

W L T Ws dL L/W T/W Ws/W W/dL Number of individuals 60 54 53 55 53 54 53 55 53

Mean value 30.47 30.77 25.9 14.57 24.08 1.01 0.86 0.48 1.27 Standard deviation 3.2916 3.9919 4.4912 2.0632 2.7598 0.1058 0.1096 0.0625 0.1078 Standard error± ±0.4249 ±0.543 ±0.6169 ±0.2782 ±0.3791 ±0.0144 ±0.015 ±0.0084 ±0.0148 Min 22 21.3 14.9 9 18.6 0.78 0.57 0.34 1.09

Max 39 39.1 35.1 20 29.1 1.21 1.21 0.6 1.52

and triangular ventral interarea, divergent dental plates, and an unsupported ctenophoridium. However, Aramazdospirifer n. gen. differs from Uchtospirifer by its much more inflated shell, acute to mucronate cardinal extremities, wider hinge line, clearly defined longitudinal and median elevation in sulcus and similar elevation often developed on fold, and the type of pseudodeltidium formed by several distinct plates. Furthermore, it is worth noting that Aramazdospirifer n. gen. has narrower ribs perceptible along the whole length of its sulcus and fold, whereas the median ribs of Uchtospirifer are variably developed, sometimes flattened to imperceptible or absent. Moreover, the micro-ornament of the new genus lacks the tubercles observed on Uchtospirifer .

Externally Aramazdospirifer n. gen. resembles also to the Famennian genus Wenjukovispirifer Oleneva, 2016 mainly in terms of its rounded subpentagonal outline, ventribiconvex lateral profile, acute to mucronate cardinal extremities, wide hinge line, well-defined and triangular ventral interarea, wide sulcus and fold bearing bifurcating ribs that are narrower than those present on the flanks. However, Aramazdospirifer n. gen. differs by its median and longitudinal elevation in sulcus and similar elevation frequently displayed on fold, and its pseudodeltidium that is formed by several distinct plates with minute submesothyrid foramen. Additionally, Aramazdospirifer n. gen. lacks pustules that are observed in Wenjukovispirifer . It is difficult to compare the internal morphology of these genera as Oleneva (2016) did not illustrate any serial sections. Nevertheless, she mentioned the presence of a median septum situated in the ventral interior of Wenjukovispirifer , a character that is not observed in Aramazdospirifer n. gen.

The new genus differs strongly from Cyrtospirifer Nalivkin in Frederiks 1924, by its more globular, longitudinally elongated and inflated shell, well-developed pseudodeltidium, longitudinal and median elevation in sulcus and similar elevation often developed on fold and the type of micro-ornament. Internally, these genera appear to be similar, though Aramazdospirifer n. gen. possesses an unsupported ctenophoridium, while the latter is supported by an apical callosity in many Cyrtospirifer representatives.

Aramazdospirifer n. gen. is distinguished externally from Lamarckispirifer Gatinaud, 1949 sensu Ma & Day (2007) , known from the lower Famennian of South China ( Ma & Day 1999), by its more rounded and inflated shell, longitudinal and median elevation in sulcus and analogous elevation often developed on fold and its high tongue. Additionally, Aramazdospirifer n. gen. lacks a median furrow on fold of the dorsal valve and the hayasakai - type micro-ornament. Internally, the most substantial difference is the presence of a dorsal median septum in Lamarckispirifer , while this character is absent in Aramazdospirifer n. gen.

Aramazdospirifer n. gen. can be distinguished from the genus Pseudocyrtiopsis Ma & Day, 1999 , known from the lower Famennian of South China, by its shell outline, longitudinal and median elevation in sulcus and analogous elevation often developed on fold, simple and flattened ribs, lack of well-developed pustules in ribs and interspaces. Internally, Aramazdospirifer n. gen. differs by its unsupported ctenophoridium.