The identity of the Permian kalenterid Netschajewia Licharev, 1925 has been uncertain because its author indicated it could be regarded as a replacement name for the preoccupied Modiolodon Netschajew, 1894 yet Newell (1957) treated Netschajewia as a subgenus of Stutchburia Etheridge Jr., 1900, and designated a type species different from that proposed by La Rocque and Newell (1969) for Modiolodon Netschajew. Netschajewia is confirmed as a replacement name for Modiolodon, thereby invalidating Newell′s (1957) erroneous type designation (misidentified type species) for Netschajewia. The names Ivanovia Astafieva-Urbajtis in Astafieva-Urbajtis and Ramovš, 1978 and Astafia Goncharova, 2013 are objective junior synonyms of Netschajewia. Netschajewia is definitely known only from its type species and one additional Permian species. It is assigned to the kalenterid subfamily Myoconchinae. The genus Verneuilnodon Fang & Carter, gen. nov. (subfamily Healeyinae Hautmann, 2008, reduced in rank herein from family Healeyidae) is proposed for Permian Mytilus (Modiola) pallasi de Verneuil, 1845, as restricted herein. The new Permian species, Kasimlara? antiqua (subfamily Healeyinae) is proposed. The wide circulation of Chavan′s (1969) republication of Newell′s (1957) erroneous type designation for Netschajewia means that modern references to this genus should be reevaluated.
INTRODUCTION
Licharev1 (1925, p. 149) introduced Netschajewia as a replacement name for Modiolodon Netschajew, 1894, a name preoccupied by Modiolodon Ulrich (1894a). La Rocque and Newell (1969, p. N397) regarded Ulrich′s Modiolodon as a member of the family Modiomorphidae S. A. Miller, 1877, but the phylogenetic analysis of early Bivalvia by Carter, Campbell, and Campbell (2006) placed Ulrich′s Modiolodon in the infraclass Pteriomorphia Beurlen, 1949 in a polytomy with the family Cyrtodontidae Ulrich, 1894b and the Eupteriomorphia Boss, 1982. This is compatible with Pojeta′s (1971, pl. 13, fig. 8) illustration of multiple, nearly horizontal, opisthodetic ligament grooves in Modiolodon oviformis (Ulrich, 1890), which comprise a monovincular-P ligament as defined by Carter and others (2012). In contrast, Netschajewia has a parivincular ligament and is a member of the infraclass Heteroconchia Hertwig, 1895, superfamily Kalenteroidea Marwick, 1953.
Netschajew (1894) published Modiolodon as a subgenus of Modiolopsis Hall, 1847 after March 1, 1894. Licharev (1925) and Pojeta (1971) indicated 1893 as the publication date for Modiolodon Ulrich, 1894a (the date indicated on the title page for Volume 7, Part 2), but the preface to Ulrich′s work (p. xiv) indicates that Part 1, Economic Geology, was issued in 1893, whereas the remainder of the text (which includes Modiolodon) was issued in 1894. The exact date in 1894 is unknown, but this probably predates the June 16, 1894 publication date of Ulrich (1894b). According to La Rocque and Newell (1969, p. 397), Modiolodon Netschajew, 1894 was probably published late in 1894.
Newell (1957) designated the type species of Netschajewia as Mytilus pallasi de Verneuil, 1845, but Newell was apparently unaware of Licharev′s (1925) indication that Netschajewia is a replacement name for Modiolodon Netschajew. As a replacement name, Netschajewia should have taken the same type species as designated by La Rocque and Newell (1969a, p. 397) for Modiolodon Netschajew, i.e., Clidophorus [err. pro Cleidophorus] pallasi oblongus Golowkinsky, 1869.
This article reviews the taxonomic history of Modiolodon Netschajew, 1894, Netschajewia Licharev, 1925 and closely related taxa in de Verneuil (1845), Golowkinsky (1869), Netschajew (1894), and Licharev (1925, 1939). The history of this nomenclature is summarized in Table 1. It also discusses the close relationship between the family Kalenteridae Marwick, 1953 and the family Healeyidae Hautmann, 2008.
Table 1.
Comparison table of Netschawejia Licharev, 1925 and related taxa names identified by Verneuil (1845), Golowkinsky (1869), Netschajew (1894), Licharev (1925, 1939) and this paper.
From Modiolodon Netschajew, 1894 to Netschajewia Licharev, 1925
The history of Modiolodon Netschajew, 1894 and Netschajewia Licharev, 1925 begins with de Verneuil′s (1845) publication of his new species Mytilus (Modiola) pallasi. De Verneuil′s specimens (Fig. 1) are variable in terms of shell length/height and projection of the anteroventral margin. De Verneuil attributed this variation to allometric growth, but Netschajew (1894, p. 238) disagreed, noting that his more elongate pallasi specimens do not change shape with increasing size. Netschajew (1894, p. 238) indicated that de Verneuil′s least elongate pallasi specimen (Fig. 1.7) might belong to his new species Modiolopsis globosus, which has an elongate lunule and an escutcheon (Fig. 3.9–3.11). Licharev (1925, p. 123) assigned Modiolopsis globosa to Netschajewia. Lutkevich and Lobanova (1959, 1960) subsequently designated the lectotype of Netschajewia (Angarodon) globosa as Netschajew′s (1894, pl. 8, fig. 17) (Fig. 3.9). Lutkevich and Lobanova (1959) justified placement of globosa in Netschajewia on the basis that its growth increments are imbricated. However, the presence of an escutcheon suggests closer affinity with Stutchburia Etheridge Jr., 1900. Stutchburia resembles Netschajewia in having obsolescent cardinal teeth but differs in having an escutcheon and posterior lateral dentition (Chavan, 1969, p. 548).
A subset of de Verneuil (1845) figured specimens of Mytilus (Modiola) pallasi are herein designated types for pallasi as presently restricted (Fig. 1.1–1.5). The de Verneuil specimen in Fig. 1.6 might represent a less elongate member of this species or an unnamed species. de Verneuil′s specimen in Fig. 1.7 is classified herein as Stutchburia? globosa (Netschajew, 1894) (Table 1).
Golowkinsky (1869) named three morphological variations (not written as varieties) of Mytilus (Modiola) pallasi based on Permian specimens from western Russia (Table 1). These are Cleidophorus pallasi oblongus, Cleidophorus pallasi obliquus, and Cleidophorus pallasi rectangularis (his Plate 4, fig. 4–13) (Fig. 2). Golowkinsky′s assignment of pallasi to Clidophorus (a misspelling of Cleidophorus Hall, 1847) was not adopted by subsequent authors. The type species of Cleidophorus, Late Ordovician Nuculites planulata Conrad, 1841 resembles some of de Verneuil′s (1845) pallasi specimens in its elongate-ovate, posteriorly extended shape, anterior myophoric buttress, and, according to Hall (1847, p. 300), its edentulous hinge. However, Golowkinsky (1869) included certain dentate species in his concept of Cleidophorus, reflecting his adoption of McCoy′s (1855) opinion that the dentate genus Pleurophorus King, 1844 (now Permophorus Chavan, 1954) is a junior synonym of Cleidophorus. The hinge structure of Nuculites planulata is unknown (see McAlester, 1968, p. 20), but McAlester (1969, p. 233) regarded Cleidophorus as a junior synonym of the nuculoid genus Nuculites Conrad, 1841.
Figure 1.
1–7, de Verneuil′s (1845) figures for Mytilus (Modiola) pallasi Verneuil (1845, pl. 19, figs. 16a–i, k). 1–5, Verneuilnodon pallasi as defined herein: 1, lectotype, exterior and interior views of right valve; 2–5, paralectotypes, 2a, left exterior view, 2b, dorsal view, 3a, right exterior view showing commarginal and traces of posterior radial sculpture, 3b, right interior view; 4, right exterior view; 5, right exterior view. 6, an atypical Verneuilnodon pallasi or an unnamed species, right exterior view. 7, specimen indicated by Netschajew (1894) as a possible Modiolopsis globosus Netschajew, 1894 (but probably a Stutchburia), right exterior view. Scale bars = 5 mm in 1–6, 2 mm in 7.
Figure 2.
Golowkinsky′s (1869, pl. 4, fig. 4–13) three morphological variations of Cleidophorus pallasi. 1, Cleidophorus pallasi obliquus after Golowkinsky (1869, pl. 4, fig. 12) [=now Netschajewia oblonga (Golowkinsky, 1869)]. 2–7, Cleidophorus pallasi obliquus after Golowkinsky (1869, pl. 4, fig. 4–8, 13) [2.2, 2.3, and 2.6 are now Verneuilnodon pallasi; 2.4 and 2.5 are now the lectotype (2.5) and paralectotype (2.4) of obliquus as restricted herein (genus indeterminate); 2.7 is now Netschajewia elongata (Netschajew, 1894)]. 8–10, Cleidophorus pallasi rectangularis after Golowkinsky (1869, pl. 4, fig. 9–11), possibly a junior synonym of Pleurophorina simpla (Keyserling, 1846). Scale bars = 10 mm in 1–3, 5–8, 10; 5 mm in 4,9.
Netschajew (1894) placed two species in his new subgenus Modiolopsis (Modiolodon): Golowkinsky′s (1869) Cleidophorus pallasi oblongus and Netschajew′s new species Modiolopsis (Modiolodon) elongatum (Table 1). Netschajew did not designate a type species for Modiolodon, but La Rocque and Newell (1969, p. 397) designated Clidophorus pallasi oblongus (Fig. 2.1) as the type by original designation (actually by subsequent designation). Modiolopsis (Modiolodon) (Netschajew, 1894) (herein Netschajewia) and its two original species (oblongum and elongatum) are described in the systematics section below. Netschajewia is assigned to the kalenterid subfamily Myoconchinae Newell, 1957 because of its modioliform shape, parivincular ligament, and the fact that its strong reduction of hinge dentition is approximated in some members of Myoconchinae. Netschajewia differs from other members of Myoconchinae in having two or more minute, short, tabular, vertically stacked, hinge-parallel cardinal teeth and no posterior lateral teeth.
Golowkinsky′s (1869, pl. 4, fig. 4–8, 13) (Fig. 2.2–2.7) Cleidophorus pallasi obliquus has a highly variable lateral profile. Netschajew (1894, p. 228) criticized Golowkinsky′s lumping such a broad range of forms under one name, so he restricted obliquus to exclude Golowkinsky′s (1869) pl. 4, fig. 13 (Fig. 2.7), which Netschajew (1894) renamed Modiolopsis (Modiolodon) elongatum (herein Netschajewia elongata). Netschajew also excluded from obliquus Golowkinsky′s (1869) pl. 4, fig. 4 and 5 (Fig. 2.2, 2.3), which Netschajew assigned to Modiolopsis pallasi, i.e., Modiolopsis (Modiolopsis), not Modiolopsis (Modiolodon). Golowkinsky′s (1869) pl. 4, fig. 6 (Fig. 2.6) has a shape similar to pallasi as restricted herein, so we tentatively include it in Verneuilnodon pallasi. The two remaining obliquus specimens in Golowkinsky (1869, pl. 4, fig. 7, 8) (Fig. 2.4, 2.5) have similarly straight dorsal margins and straight or nearly straight ventral margins. However, one specimen (Fig. 2.4) is moderately elongate and dorsoventrally expanded posteriorly, whereas the other (Fig. 2.5) is more elongate and not dorsoventrally expanded posteriorly. Because these might represent different species, we designate Fig. 2.5, which alone shows the shell sculpture, as lectotype and Fig. 2.4 as paralectotype for obliquus. Unfortunately, the hinge dentition is unknown for obliquus so it is not possible to assign it to a genus. In summary, Golowkinsky′s specimens of Cleidophorus pallasi obliquus are herein classified as obliquus sensu stricto (generically indeterminate) (Fig. 2.4–2.5), tentatively (because of a lack of information on hinge structure) Verneuilodon pallasi (de Verneuil, 1845) (Fig. 2.2–2.3, 2.6), and Netschajewia elongata (Netschajew, 1894) (Fig. 2.7) (Table 1).
Figure 3.
Netschajewia and allied taxa. 1–2, “Netschajewia pallasi (de Verneuil, 1845)”, after Licharev (1939, pl. 35, fig. 10–11) (=now Verneuilnodon pallasi); 1a, right exterior view showing commarginal sculpture; 1b, right interior view (Fig. 3.1 is the same specimen as Fig. 1.1). 2, Right internal mold. 3–6, “Modiolopsis pallasi de Verneuil” after Netschajew (1894, pl. 8, fig. 1–4); 3a, 3c, “left” (actually right) internal molds, 3b, plaster cast of 3a, with labels α (anterior adductor muscle scar), β (myophoric ridge) and γ (anterior pedal retractor muscle scar), 3c is labeled as in 3b. 4, Left composite mold. 5, Right composite mold. 6, Right composite mold (3–6 = now Kasimlara? antiqua, sp. nov.). 7–8, “Modiolopsis (Modiolodon) oblongum” (Golowkinsky, 1869), after Netschajew (1894, pl. 8, fig. 9, 15) (= now Netschajewia oblonga); 7, right internal mold; 8, left internal mold. 9–11, “Modiolopsis globosus” Netschajew, 1894 (= now Stutchburia? globosa), after Netschajew (1894, pl. 8, fig. 16–18); 9, left internal mold of globosus lectotype; 10, left internal mold; 11, right internal mold. 12–16, “Stutchburia? modioliformis” (King, 1848) after Newell (1955, pl. 5, fig. 1–5); 12, juvenile specimen in posterior dorsal view (12a), left exterior view (12b), and anterior dorsal view (12c). 13, left exterior view; 14, left exterior view showing costellate sculpture; 15, right exterior view; 16, right internal mold. 17, “Netschajewia cf. modioliformis” (King, 1848), after Newell (1957, fig. 2D), left (17a) and right (17b) interior views, with myophoric ridge indicated by b, hinge teeth indicated by t, and tooth sockets shown in stippling (= Stutchburia modioliformis (King) in Logan, 1967, p. 51). Scale bars = 5 mm in 1–8, 2 mm in 9–11 and 14–17, 1 mm in 12, 13.
Golowkinsky (1869, pl. 4, fig. 9–11) described his Cleidophorus pallasi rectangularis (Fig. 2.8–2.10) as dentate, but the hinge structure is not visible in his illustrations. Netschajew (1894, p. 230) and Branson (1948) regarded rectangularis as a junior synonym of Modiola simpla Keyserling, 1846 (p. 260, pl. 10, fig. 22, pl. 14, fig. 1), the type by monotypy of Pleurophorina Licharev (1925, pl. 2, fig. 1–4). Keyserling (1846) did not describe the hinge of Modiola simpla, but Netschajew (1894, p. 305–306), who classified this species as Pleurophorus simplus (Keyserling), indicated two cardinal teeth and one posterior lateral tooth in each valve. The left valve has a short, thick cardinal tooth and above this a thinner, longer cardinal tooth. The right valve has two lamellar cardinal teeth above a triangular socket, and the cardinal tooth closest to this socket is short, whereas the other cardinal tooth is longer. However, Maslennikov (1935, p. 82) described the hinge dentition of Modiola simpla differently, indicating a triangular cardinal socket and one long posterior lateral tooth in the left valve, and one cardinal tooth and possibly a posterior lateral tooth in the right valve. Maslennikov (1935) concluded that the simple cardinal dentition and absence of a lunule and escutcheon exclude Modiola simpla from Pleurophorus King, 1844 (=Permophorus Chavan, 1954). Because of uncertainty in the hinge structure of this species, we accept the conclusion by Morris, Dickins, and Astafieva-Urbajtis (1991, p. 84) that the possibility that Pleurophorina is a senior synonym of Permophorus remains unsettled. Fang and Morris (1997) regarded Pleurophorina as a nomen dubium unless Modiola simpla becomes properly interpreted.
Mytilus (Modiola) pallasi de Verneuil, 1845, as presently restricted to Fig. 1.1–1.5, Fig. 2.2–2.3, 2.6, and Fig. 3.1–3.2, is designated herein as the type for the new genus Verneuilnodon Fang & Carter herein. Verneuilnodon and its member species are described in the systematics section below. Verneuilnodon differs from Netschajewia in having a banana-like instead of elongate-ovate shape, with the posterior dorsal and ventral margins both curving downward posteriorly; in having a broad, shallow ventral sinus; and in lacking hinge teeth. Netschajew (1894, p. 230) confirmed de Verneuil′s (1845) description of the hinge of pallasi as edentulous. The absence of hinge teeth excludes Mytilus (Modiola) pallasi from the subfamilies Kalenterinae and Myoconchinae. We regard Verneuilnodon as closely related to the Triassic genus Healeya Hautmann, 2001, which Hautmann (2008) assigned to the family Healeyidae, but which we reduce herein in rank to subfamily Healeyinae in Kalenteridae. Healeya gonoides (Healey, 1908), the generic type species, resembles Verneuilnodon pallasi in being strongly inequilateral, thick-shelled, posteriorly expanded, slightly posteroventrally extended, and ventrally broadly and slightly sinuate, with an associated slight sulcus. Both species also have an edentulous, slightly arched hinge, an anterior myophoric buttress, and an opisthodetic, parivincular ligament. Healeya gonoides differs from Verneuilnodon pallasi in having a subtriangular instead of banana-like shape, a straighter dorsoposterior margin, a sharply defined instead of rounded umbonal-posteroventral carina, and a permanent byssal gape. Verneuilnodon is unique in the Kalenteridae for its combination of a banana-like shape, ventrally curving posterior margins, broad, shallow, ventral sinus, slightly arched edentulous hinge, anterior myophoric buttress, and opisthodetic, parivincular ligament.
A Permian specimen identified as Modiolopsis pallasi by Netschajew (1894, pl. 8, fig. 1a–c) (Fig. 3.3) has a shape similar to the holotype of Late Triassic Kasimlara kosuni Kiel, 2018 (Kiel, 2018, fig. 4A), the type species of Kasimlara Kiel, 2018. Both specimens are strongly posteriorly extended, anteriorly roundly lobate, ventrally nearly straight to deeply concave, posteriorly broadly ovate, and have very low, almost terminally anterior umbos separated from a subadjacent anterior shell lobe by a distinct notch. Both also have a deeply impressed anterior adductor muscle scar positioned on an anterior shell lobe. Two other figures of Modiolopsis pallasi in Netschajew (1894, pl. 8, fig. 3–4) (Fig. 3.5–3.6) resemble a paratype of Kasimlara kosuni (see Kiel, 2018, fig. 4B), with umbos extending anteriorly beyond the anteroventral shell margin. Plate 8, fig. 2 in Netschajew (1894) (Fig. 3.4) might represent a variation of the Permian species in which the anterior lobe of the shell is subdued. Netschajew′s (1894) specimens lack hinge teeth, but the hinge structure of Kasimlara kosuni is unknown. Netschajew′s Permian specimens differ from Kasimlara kosuni in being equivalve, in lacking a pallial sinus, and in having an anterior myophoric ridge. Kasimlara kosuni is slightly inequivalve, with the posterior end of the shell curving indifferently to the left or right; it has a small, pointed pallial sinus; and it lacks a myophoric ridge bordering the anterior adductor muscle scar. Netschajew′s (1894, pl. 8, fig. 1–4) specimens are herein designated types for Kasimlara? antiqua Fang & Carter n. sp., herein, with the holotype Netschajew′s (1894) pl. 8, fig. 1 (Fig. 3.3), and paratypes his pl. 8, fig. 2–4 (Fig. 3.4–3.6). The name antiqua refers to the Permian age of Kasimlara? antiqua relative to Triassic Kasimlara kosuni. Because of the lack of hinge teeth (at least in Kasimlara? antiqua), Kasimlara is tentatively assigned to the edentulous subfamily Healeyinae.
The type species of Modiolodon Netschajew and Netschajewia Licharev
Licharev (1925) indicated that Netschajewia could be regarded as a replacement name for Modiolodon Netschajew. He wrote (1925, p. 123, translated herein) “I do not consider the separation of Modiolodon from Netschajewia to be rational. In such a case the name Modiolodon proposed by Netschajew could completely replace the name Netschajewia introduced by me, if it had not been eclipsed by Ulrich a year before the publication of Netschajew′s monograph for another genus of pelecypods”. [Original text “Gegenwärtig mich nur auf den Hinweis dieses engen Zusammenhanges beschränkend, halte ich jedenfalls die Trennung des Modiolodon von Netschajewia nicht für rationell. ln solchem Falle könnte die von Netschajew vorgeschlagene Benennung (Modiolodon) volkommen die von mir eingeführte Bezeichnung Netschajewia ersetzen, wenn dieselbe nicht ein Jahr vor dem Erscheinen der Monographie Netschajew′s für die andere Gattung der Pelecypoden [XL, 521] von Ulrich übertroffen worden wäre.”]
Newell (1957) treated Netschajewia as a subgenus of Stutchburia. Not realizing that Netschajewia had been proposed as a replacement name for Modiolodon Netschajew, Newell designated Mytilus pallasi i.e., Mytilus (Modiola) pallasi de Verneuil, 1845, as the type. This type designation was accepted by Chavan (1969). Newell (1957) was unaware of the restriction of pallasi to edentulous shells by Netschajew (1894) and Licharev (1925, 1939), as evidenced by the fact that he synonymized pallasi with the dentate Pleurophorus modioliformis King, 1884 (i.e., Cardiomorpha modioliformis King, 1848 not 1884). Newell (1957) used an original figure for his Netschajewia cf. modioliformis (Fig. 3.17) instead of one of de Verneuil′s (1845) figures for Mytilus (Modiola) pallasi. Unfortunately, Newell′s (1957) figure differs from pallasi, as presently defined, in having posterior lateral dentition and a more angulate anteroventral margin. Chavan (1969, p. 545) and Kiel (2018) accepted Newell′s (1957) synonymy of pallasi (de Verneuil) and modioliformis (King). Chavan (1969, fig. E44.3) reused Newell′s (1957) figure of modioliformis to illustrate the type species of Netschajewia (although Chavan omitted the cf. before modioliformis). Newell′s (1955, pl. 5, fig. 1–5) (Fig. 3.12–3.16) illustration of Stutchburia? modioliformis differs from King′s (1848) modioliformis in lacking an escutcheon. Not surprisingly, Muromzeva and Guskov (1984) were reluctant to recognize pallasi and modioliformis as synonyms. Additionally, Logan (1967, p. 51) expressed doubt about the identity of Newell′s (1955, p. 28, pl. 5, fig. 1–5) Stutchburia? modioliformis with King′s (1848) modioliformis, because Newell′s specimens lack a lunule and escutcheon. However, Logan (1967) listed Newell′s (1957) illustration of Netschajewia cf. modioliformis in his synonymy of Stutchburia modioliformis (King). King (1848, 1850, p. 180, pl. 14, fig. 18–23) did not describe the hinge of Cardiomorpha modioliformis. It is unclear whether the specimens illustrated by Newell (1955, 1957) and Chavan, 1969, p. 545) are modioliformis King, 1848 or a related species.
Nakazawa and Newell (1968, p. 95) and Manceñido, Gonzalez, and Damborenea (1976) accepted Licharev′s (1925) suggestion that Netschajewia is a replacement name for Modiolodon Netschajew. Doing so gave Netschajewia the same type species as Modiolodon on the principle of typification of a replaced name (ICZN, 1999, Article 67.8), i.e., Cleidophorus pallasi oblongus Golowkinsky, 1869, as designated for Modiolodon Netschajew by LaRocque and Newell (1969, p. N397).
Because Newell (1957) misidentified the type species of Netschajewia, it would be possible to invoke ICZN (1999) Article 70.3, concerning misidentified type species, and replace Newell′s (1957) type designation. However, this step is not necessary because confirmation that Netschajewia is a replacement name for Modiolodon (Netschajew) invalidates Newell′s (1957) type designation. Two later published replacement names for Modiolodon (Netschajew) are now objective junior synonyms of Netschajewia: Ivanovia Astafieva-Urbajtis in Astafieva-Urbajtis and Ramovš (1978) and Astafia Goncharova, 2013.
Taxonomic position of Netschajewia and Verneuilnodon
Chavan (1969, p. 545) assigned Netschajewia to the kalenterid subfamily Kalenterinae Marwick, 1953, but the subfamily Myoconchinae is more appropriate. Kalentera Marwick, 1953 and Myoconcha J. de C. Sowerby, 1824 both have well-developed cardinal and posterior lateral hinge teeth, but the myoconchine genus Stutchburia approaches Netschajewia in having obsolescent cardinal teeth and partially obsolescent posterior lateral teeth (Chavan, 1969, p. 548), the latter teeth being entirely absent in Netschajewia. The presence of cardinal hinge dentition in Netschajewia excludes it from the edentulous subfamily Healeyinae.
Verneuilnodon is assigned to the subfamily Healeyinae instead of Myoconchinae because its hinge is edentulous. Hautmann (2008) included in his new family Healeyidae, Triassic Healeya Hautmann, 2001; Middle Triassic Joannina Waagen, 1907; and, questionably, Middle Triassic Protopis Kittl, 1904 as well as three additional Middle Triassic genera proposed by Stiller and Chen (2006): Leidapoconcha, Qingyaniola, and Waijiaoella. In addition to being edentulous, Verneuilnodon pallasi resembles Late Triassic Healeya gonoides (Healey, 1908) in terms of its thick, strongly inequilateral shell with low, rounded, strongly anterior umbos; posteriorly downwardly sloping, shallowly sinuate ventral margins; adductor muscle scars positioned close to a more or less lobate anterior shell margin; and anterior myophoric ridge. Verneuilnodon pallasi differs from Healeya gonoides in being posteriorly ovate instead of subtruncate, in having a broadly convex instead of nearly straight dorsoposterior margin, in having a more rounded umbonal-posteroventral carina, and in lacking a permanent byssal gape. The family Healeyidae is herein reduced in rank to subfamily Healeyinae because Healeya gonoides is morphologically and ligamentally similar to some Kalenterinae and Myoconchinae and differs from Myoconchinae principally in having a more extreme reduction of the hinge dentition. Hautmann (2008) assigned Healeyidae to the family Modiomorphidae, but Modiomorpha Hall in Hall and Whitfield, 1869, as exemplified by its type species Devonian Modiomorpha concentrica (Conrad, 1838), differs from Healeya and other members of Kalenteridae in having a wider, flatter, subumbonal hinge plate; cruder cardinal dentition consisting of dorsally reflected, irregular shell lamellae; and a deeper, more strongly growth-lined lunule (Carter, 1990, p. 266). Additionally, Modiomorpha concentrica has a nacreous shell, whereas members of Kalenteridae are internally porcelaneous and non-nacreous (Carter & Tevesz, 1978; Morris, 1978, p. 273; Carter, Lutz, & Tevesz, 1990, p. 391).
SUMMARY
Netschajewia Licharev, 1925 is confirmed as a replacement name for the preoccupied Modiolodon Netschajew, 1894 (non Modiolodon Ulrich, 1894a), thereby invalidating Newell′s (1957) designation of a type species for Netschajewia that is different from the type for Modiolodon Netschajew, 1894. The figures that Newell (1957) used to illustrate the type species of Netschajewia (also used by Chavan, 1969) are actually Stutchburia or a closely related, dentate species. Netschajewia is distinguished from other members of Myoconchinae by having two or more minute, vertically stacked, hinge-parallel, tabular cardinal teeth, no additional cardinal teeth, and no posterior lateral teeth. The confusion stemming from Newell′s (1955, 1957) misidentification of the type species of Netschajewia means that subsequent references to this genus need to be reevaluated.
De Verneuil′s (1845) Mytilus (Modiola) pallasi is herein restricted to its edentulous members, and this pallasi sensu stricto is designated the type species for the new genus Verneuilnodon. The dentate example of de Verneuil′s (1845) Mytilus (Modiola) pallasi is now Stutchburia? globosa (Netschajew, 1894). Verneuilnodon is assigned to the edentulous kalenterid subfamily Healeyinae, herein reduced in rank from family Healeyidae Hautmann, 2008. Verneuilnodon resembles Healeya gonoides (Healey, 1908) in many respects, but differs in having a banana-shaped instead of subtriangular profile; a convex instead of nearly straight dorsoposterior margin; a lower, more rounded umbonal-posteroventral carina; and no byssal gape.
The new Permian species Kasimlara? antiqua Fang & Carter is proposed for members of Healeyinae with a lateral profile similar to Late Triassic Kasimlara kosuni Kiel, 2018, but with shells equivalve, not curving to the left or right as in K. kosuni, with a myophoric buttress (absent in K. kosuni), and without a pallial sinus (short and pointed in K. kosuni).
Additional taxonomic actions are summarized as follows: Licharev′s (1925, 1939) Netschajewia pallasi (de Verneuil, 1845) is subdivided into Verneuilnodon pallasi, Stutchburia? globosa, and possibly an unnamed species closely related to Verneuilnodon pallasi. Golowkinsky′s (1869) Cleidophorus pallasi obliquus is subdivided into obliquus sensu stricto (genus indeterminate), Verneuilnodon pallasi (de Verneuil, 1845), and Netschajewia elongata (Netschajew, 1894). Golowkinsky′s (1869) Cleidophorus pallasi oblongus is now Netschajewia oblonga (Golowkinsky, 1869), the type species of Netschajewia by the principle of typification of a replacement name for Modiolodon Netschajew, 1894. Golowkinsky′s (1869) Cleidophorus pallasi obliquus, as restricted herein, is generically indeterminate. Netschajew′s (1894) Modiolopsis pallasi (de Verneuil, 1845) is subdivided into Verneuilnodon pallasi (de Verneuil, 1845) and Kasimlara? antiqua sp. nov.. Netschajew′s (1894) Modiolopsis (Modiolodon) elongatum is now Netschajewia elongata (Netschajew, 1894).
SYSTEMATICS
Superfamily Kalenteroidea Marwick, 1953
Family Kalenteridae Marwick, 1953
Subfamily Myoconchinae Newell, 1957
Netschajewia Licharev, 1925
(nom. nov. pro Modiolodon Netschajew, 1894, non Ulrich, 1894a)
Type species.—Clidophorus [err. pro Cleidophorus] pallasi oblongus Golowkinsky, 1869, by typification of replacement name for Modiolodon Netschajew, 1894, non Modiolodon Ulrich, 1894a, as designated for Modiolodon Netschajew by La Rocque and Newell (1969, p. 397).
Generic diagnosis.—Members of Myoconchinae with two or more minute, short, tabular, vertically stacked, hinge-parallel cardinal teeth and no posterior lateral teeth.
Generic description.—Netschajew (1894, p. 239–240) described Modiolopsis (Modiolodon) (herein Netsachajewia) as of considerable size, very thick shelled, straight or slightly curved, very elongate, with strongly impressed anterior adductor muscle scar; pronounced posterior adductor muscle scar; wide, irregular myophoric buttress bordering the anterior adductor scar; anterior pedal retractor muscle scar positioned dorsal to this buttress; simple, strongly impressed, non-sinuate pallial line; umbos almost terminally anterior and not prominent; slightly concave ventral shell margin, and two or more minute, short, tabular, vertically stacked, parallel cardinal teeth. Added herein, no posterior lateral teeth; shells equivalve, strongly inequilateral, strongly posteriorly extended, elongate ovate (oblonga) to elongate subtriangular (elongata), and no permanent byssal gape. Sculpture varying from entirely commarginal to also radial. Pallial line well recessed from ventral shell margin. Any concavity of ventral shell margin that might be present (as in elongata, see Netschajew, 1894, pl. 8, fig. 19) very shallow. [Netschajew (1894) illustrated two internal molds of oblongus that reveal the hinge structure (Fig. 3.7–3.8).]
Member species.—The two original species of Modiolopsis (Modiolodon) Netschajew are now called Netschajewia oblonga (Golowkinsky, 1869) and Netschajewia elongata (Netschajew, 1894). Netschajewia oblonga, the type species, can be described as follows, based on Golowkinsky (1869) and Netschajew, 1894): Shells medium size (up to 85 mm long), equivalve, moderately to strongly (?) inflated, strongly inequilateral, strongly posteriorly extended; margins not gaping, dorsal and ventral margins only slightly diverging from anterior to posterior; posterior margin slightly more broadly ovate than anterior margin. In lateral profile, shells elliptical, anterior margin narrowly to moderately ovate; anterior part of dorsal margin very short, nearly horizontal or curving downward, probably without a distinct indentation directly anterior to beaks (although this is difficult to evaluate from internal molds); ventral margin very broadly ovate to nearly straight, and nearly horizontal to sloping slightly downward toward posterior, passing smoothly into posterior margin, which is moderately ovate; posterior part of dorsal margin very weakly convex and sloping slightly upward toward posterior, passing smoothly into posterior margin. Presence or absence of lunule and escutcheon unknown. Sculpture of growth lines or ridges and obscure radial ribs, the latter extending from umbo to posterior margin. Umbonal-posteroventral carina probably not well developed, judging from internal molds. Umbos probably low, not projecting, strongly anterior but not terminally so. Anterior adductor muscle scar roundly ovate, deeply impressed, positioned directly below anterior hinge, close to anterior shell margin. Posterior adductor muscle scar nearly twice as large, subcircular, more shallowly impressed, positioned directly below posterior end of hinge. Anterior pedal retractor muscle scar small, positioned dorsal and adjacent to anterior adductor scar. Short myophoric ridge present along posterior margin of anterior adductor muscle scar, extending posteroventrally from below anterior hinge. Pallial line continuous, deeply impressed, well removed from ventral and posterior shell margins, without sinus. Anterior end of pallial line contacting posteroventral margin of anterior adductor scar; posterior end of pallial line contacting medioposterior margin of posterior adductor scar. Interior shell surface directly proximal to ventral pallial line bulging more or less abruptly outward (laterally) relative to shell directly distal to pallial line. Hinge slightly arched, very short and narrow to moderately wide anterior to beaks, much longer and (possibly?) narrower posterior to beaks (width of posterior hinge difficult to determine from internal molds). Each valve with three minute, short, tabular, vertically stacked, hinge-parallel cardinal teeth and no lateral teeth. Ligament opisthodetic; ligament insertion area not seen, but probably parivincular.
Netschajewia elongata (Netschajew, 1894) resembles Netschajewia oblonga in having minute, short, tabular, vertically stacked, hinge-parallel cardinal teeth, an elongate-ovate shell not curving downward posteriorly, no sinus in the ventral shell margin, a moderately recessed pallial line, and a sculpture of growth lines and a few radial ribs. Both taxa also have a prominent lateral expansion of the shell′s inner surface, directly proximal to the anteroventral pallial line. Netschajewia elongata differs from Netschajewia oblonga in having fewer (only two) cardinal teeth, a flatter shell, a moderately ovate instead of narrowly ovate posterior, and nearly straight instead of convex dorsal and ventral margins. Maslennikov (1935) and Noinsky (1935) referred this species to Stutchburia, apparently assuming the presence of posterior lateral dentition.
Two additional Permian species might be members of Netschajewia. These are Netschajewia (?) sibirica Kulikov, 1967, which lacks posterior lateral dentition, and a specimen cited by Nakazawa and Newell (1968, p. 95, pl. 11, fig. 5, 6) as Netschajewia cf. elongata (Netschajew, 1894). The latter specimen was described as having a right posterior lateral tooth, but this so-called tooth is very short and does not extend far posterior to the umbo, suggesting that it might be a low ligament nymph.
The species that Newell (1957) and Chavan (1969) used to illustrate Netschajewia, Newell′s (1957, Fig. 2D) “Netschajewia cf. modioliformis (King)” is not a Netschajewia because it has a posterior lateral dentition. Newell (1957) used this species to illustrate the type species of Netschajewia because Newell (1957, p. 7) regarded “Plerophorus modioliformis King, 1884” (actually Cardiomorpha? modioliformis King, 1848, not 1884) as a synonym of Mytilus pallasi de Verneuil, 1845. Complicating this matter, Lutkevich and Lobanova (1959, p. 161) indicated that Netschajew′s (1894, p. 309, pl. 10, fig. 2, 3, 31) Permian “Cardiomorpha? modioliformis” King is not that species, so they renamed it Modiola netschajewi (see Lutkevich & Lobanova, 1959, pl. 32, fig. 10–14). Neither King (1848) nor Netschajew (1894) described the hinge structure of Cardiomorpha modioliformis.
The wide circulation of Newell′s (1957) and Chavan′s (1969) misidentification of the type species of Netschajewia means that subsequent references to this genus should be reevaluated. For example, Muromzeva and Guskov (1984) reassigned Netschajewia oblonga to Stutchburia, incorrectly believing that oblonga resembles Stutchburia in having posterior lateral dentition. Kiel (2018) indicated that his new genus Terzileria resembles Netschajewia in having posterior hinge teeth, although their absence is now considered to be a hallmark of Netschajewia. Several authors have incorrectly assigned posteriorly dentate species to Netschajewia. These include Permian Netschajewia maslennikowi Lutkevich & Lobanova, 1971 (p. 87, pl. 6, fig. 5–7); Middle Triassic Netschajewia svilajiensis Chorowicz & Termier, 1975 (their p. 240, text-fig. 10, pl. 21, fig. 13–15), and a Permian Netschajewia sp. in Manceñido, Gonzalez, and Damborenea (1976, p. 90). Sha and Grant-Mackie (1996, p. 434, fig. 3A) reassigned Permian Stutchburia jiangsuensis Liu in Gu & others, 1976, p. 97, pl. 11, fig. 8) to Netschajewia, although this species has a divided posterior lateral tooth in the left valve and two posterior lateral teeth in the right valve. The Netschajewia cf. modioliformis (King, 1848) in Sha and Grant-Mackie (1996, p. 434, fig. 3B) resembles a bakevellid in terms of its lobate anterior ear delimited posteriorly by a shallow, radial furrow, a depressed posterior wing, and umbos salient above the hinge margin. The surface of the internal mold (their fig. 3B) has vague traces of radiating ridges. This is probably a member of the Permian–Early Triassic bakevellid genus Towapteria Nakazawa & Newell, 1968. Other taxa have been assigned to Netschajewia despite a lack of information on their hinge structure, e.g., Permian Netschajewia pallasi var. kendyrlikensis Lutkevich & Lobanova, 1960 (p. 182, pl. 2, fig. 14) and Permian Netschajewia kulogorae Nelzina in Kalmykova & others (1978, p. 19, pl. 1, fig. 16, 19, 20).
Lutkevich and Lobanova (1959, p. 151) did not consider hinge dentition when they differentiated Netschajewia from Stutchburia, Myoconcha, and Permophorus on the basis that imbricated growth increments are diagnostic of Netschajewia. Consequently, their concept of Netschajewia includes some taxa with posterior lateral hinge teeth. Their new species Netschajewia striata Lutkevich & Lobanova, 1959 (pl. 32, fig. 4–7) has imbricated growth increments crossed by very narrow, closely spaced radial ribs, but these so-called ribs consist of a dense network of radial pimples, suggesting that they are actually radial rows of mineralized periostracal granules or spines, a common feature among kalenterids. Lutkevich and Lobanova (1959) did not describe the hinge structure of striata, so its placement in Netschajewia is certain. Lutkevich and Lobanova (1959, p. 152, pl. 31, fig. 5, 6) reassigned Stutchburia tschernyschewi Maslennikov, 1935 to Netschajewia, although they indicated that other authors have observed a thickened ridge (posterior lateral tooth?) on its hinge. Finally, Lutkevich and Lobanova (1959) proposed three new varieties of Netschajewa pallasi, two of which, aversa and alta, also have a thickened ridge on their hinge. Their variety aversa would be unique in Netschajewia for having a slight pallial sinus. The hinge of their third new variety, Netschajewia pallasi var. duplex, was not described, so its assignment to Netschajewia is not confirmed.
Stratigraphic distribution.—Permian of western Russia.
Subfamily Healeyinae Hautman, 2008
Verneuilnodon Fang & Carter, herein gen. nov.
Figures 1.1–1.5, 2.2–2.3, 2.6, 3.1–3.2
Type species.—Mytilus (Modiola) pallasi de Verneuil, 1845, as restricted herein to de Verneuil′s (1845) pl. 19, fig. 16a–h (Fig. 1.1–1.5), with Fig. 1.1a–b designated herein as lectotype and Fig. 1.2–1.5 designated as paralectotypes.
The new Permian genus Verneuilnodon is proposed for Mytilus (Modiola) pallasi de Verneuil, 1845, as restricted herein. The genus name honors Philippe-Édouard Poulletier de Verneuil (1805–1873), a pioneer in Paleozoic biostratigraphy. Nodon derives from the Greek vwδóç for edentulous, in reference to the absence of hinge teeth.
Generic (and type species) diagnosis.—Equivalve members of Healeyinae with banana-shaped lateral profile, convex dorsoposterior margin, slightly concave (sinuate) ventral margin, low, rounded umbonal-posteroventral carina, and no anteroventral byssal gape. Hinge edentulous.
Generic (and type species) description.—Shells small (as long as 31 mm), considerably thick, moderately inflated, moderately elongate, strongly inequilateral, strongly posteriorly extended, with dorsal and ventral margins slightly to moderately curving downward posteriorly; no permanent shell gapes. As seen in lateral profile, shells anteriorly narrowly ovate and sometimes anteroventrally lobate; anterior part of dorsal margin very short, moderately to strongly sloping downward, with slight indentation directly anterior to beaks; ventral margin broadly and shallowly sinuate (concave) and sloping slightly to strongly downward posteriorly; posterior margin generally moderately ovate and slightly higher than anterior margin; posterior part of dorsal margin very broadly arched and passing smoothly into posterior margin. Very low, rounded, umbonal-posterior carina present. Broad, shallow, ventral to anteroventral sulcus present. Very small, rather deep lunule commonly present, but no escutcheon. Sculpture of growth lines and sometimes also 3–5 narrow ribs extending posteriorly from umbo (Fig. 1.3a). Umbos very low, strongly anterior but not overhanging anterior shell margin. Anterior adductor muscle scar deeply impressed, ovate to subtriangular, positioned directly below anterior end of hinge, close to anterior shell margin, bordered posteriorly by oblique, umbonal-posteroventral, radial to slightly oblique, myophoric ridge. Other muscle scars unknown. Hinge plate narrow, edentulous, anteriorly slightly arched, posteriorly very broadly arched. Ligament external, opisthodetic, parivincular, with low, slightly submarginal nymphs.
Comparisons.—Of the two genera that Hautmann (2008) assigned without question to his family Healeyidae (herein Healeyinae), the Late Triassic Healeya Hautmann, 2008 differs from Verneuilnodon in having a triangular instead of banana-like shape, a straighter dorsoposterior margin, a sharper, more prominent umbonal-posteroventral carina, an escutcheon, and a permanent byssal gape. The second genus, Early? to Middle Triassic Joannina Waagen, 1907 differs from Verneuilnodon in having a stronger umbonal-posteroventral carina, a deeper ventral sinus, umbos projecting more dorsally than anteriorly, and an escutcheon. Kasimlara Kiel, 2018, which we tentatively include in Healeyinae, differs from Verneuilnodon in having a more strongly differentiated anterior shell lobe (at least in larger specimens), narrower, more anteriorly projecting umbos that may overhang the anterior shell margin, and a deeper notch between the umbo and the anterior shell margin. The pallial line is unknown for Verneuilnodon and most other genera in Healeyinae, but in Kasimlara this varies from non-sinuate (Permian Kasimlara? antiqua) to having a small, pointed sinus (Triassic Kasimlara kosuni). Verneuilnodon, like other members of Healeyinae, is edentulous.
Stratigraphic distribution.—Lower to upper Permian of western Russia.
Kasimlara? antiqua Fang & Carter, sp. nov.
Figure 3.3–3.6
Type specimens.—Holotype is Netschajew′s (1894) pl. 8, fig. 1 (Fig. 3.3). Paratypes include Netschajew′s (1894) pl. 8, fig. 2–4 (Fig. 3.4–3.6). Netschajew's (1894) specimens were deposited in the geology department of Kazan University (now Kazan Federal University), but we have not verified that they are still there.
Kasimlara? antiqua is proposed for Netschajew′s (1894) pl. 8, fig. 1–4, which Netschajew (1894) identified as Modiolopsis pallasi de Verneuil, i.e., Mytilus (Modiolus) pallasi de Verneuil, 1845. The name antiqua refers to the ancient age of Permian Kasimlara? antiqua relative to the Carnian, Late Triassic Kasimlara kosuni Kiel, 2018, the type species of Kasimlara Kiel, 2018, by original designation.
Diagnosis.—Members of Healeyinae resembling Late Triassic Kasimlara kosuni Kiel, 2018 in terms of shell shape, but differing from that species in being equivalve, less elongate, in having a myophoric ridge, and in lacking a pallial sinus. Smaller specimens differ from larger ones in having a more rectangular shape and a shallower or absent ventral sinus.
Description.—Based largely on Netschajew′s (1894) description and illustration of Modiolopsis pallasi de Verneuil (his pl. 8, fig. 1–4) (Fig. 3–6).—Shells small, thickness unknown, moderately to strongly inflated, moderately elongate, strongly inequilateral, strongly posteriorly or slightly to moderately posteroventrally extended; no permanent shell gapes. As seen in lateral profile, shells anteriorly moderately to very strongly lobate; anterior part of dorsal margin very short, strongly sloping or strongly curving downward, with distinct indentation between umbo and anterior margin; larger specimens with ventral margin broadly and deeply sinuate (concave) and sloping strongly downward, but smaller specimens with ventral margin straight to shallowly sinuate and sloping only slightly downward; shells posteriorly moderately to broadly ovate; larger specimens much taller posteriorly than anteriorly, some smaller specimens only slightly taller posteriorly; posterior part of dorsal margin slightly to moderately arched, passing smoothly into posterior margin. Very low, rounded, umbonal-posterior carina and slight anteroventral sulcus present. Presence or absence of lunule and escutcheon unknown. Sculpture of growth lines without radial ribs. Umbos small, strongly anterior, subterminal, terminal, or overhanging anterior shell margin. Anterior adductor muscle scar deeply impressed, positioned directly below anterior end of hinge, close to anterior shell margin, and bordered posteriorly by narrow, oblique, umbonal-posteroventral, myophoric ridge. Posterior adductor mucle scar larger, elongate, weakly impressed, positioned directly below posterior end of hinge. Anterior pedal retractor muscle scar subtriangular, positioned at dorsal end of myophoric ridge. Hinge nearly straight to slightly arched, edentulous. Ligament insertion area not observed.
Comparisons.—Kasimlara? antiqua strong resembles Kasimlara kosuni in terms of overall shell shape and in having the umbos sometimes strongly overhanging the anterior shell margin, from which they are separated by a distinct notch. However, K.? antiqua differs from K. kosuni in being equivalve (not curving posteriorly to the left or right), in having a myophoric ridge, and in lacking a pallial sinus (small and pointed in K. kosuni).
This new species is questionably assigned to Kasimlara because it is unknown whether the type species of Kasimlara, Kasimlara kosuni, is also edentulous. Netschajew′s (1894) pl. 8, fig. 1b (Fig. 3.3b) shows an elongate, lamellar internal ridge in Kasimlara? antiqua below and slightly diverging from the hinge in the right valve, but it is doubtful that this represents a lateral tooth. The posterior lateral tooth in the Netschajewia cf. modioliformis illustrated by Newell (1957, fig. 2D) is closer to the hinge and therefore more clearly a dental feature.
Kasimlara? antiqua differ from Verneuilnodon pallasi, as defined herein, in terms of its more strongly lobate anterior margin, narrower, deeper ventral sinus, more dorsoventrally expanded posterior, and more anteriorly projecting umbos.
Stratigraphic distribution.—Permian of western Russia.
ACKNOWLEDGMENTS
We thank Michael Hautmann and an anonymous reader for their critical reviews and/or editing of this manuscript. This research was supported by Special projects for basic work of science and technology of MST, China, “China′s fossil invertebrates” (2021FY200102). Fang Zong-jie expresses his gratitude to Dr. Alexandr Guzhov of Borissiak Paleontological Institute, Russia, for providing a pdf of Licharev (1925), which is not available in China. Carter is grateful to the Interlibrary Loan staff at the University of North Carolina, Chapel Hill, for obtaining a number of references essential for this paper.
Copyright © 2022, The University of Kansas, Paleontological Institute
REFERENCES
Notes
[1] 1The English translation of the Russian name Б. Лиxapeв has long been in confusion. Б. Лиxapeв used both Licharew (1925) and Licharev (1939). Newell (1957) used “Licharew” in his list of references, but “Jakolew” in his text. Chavan (1969, p. N545) used “Yakovlev.” For the sake of consistency, we use the spelling “Licharev.”
