Quasicalathus Schmidt & Will, 2022
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https://dx.doi.org/10.3897/dez.69.79931 |
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publication LSID |
lsid:zoobank.org:pub:02E8488B-DDA7-464C-ABC2-39424200939E |
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persistent identifier |
https://treatment.plazi.org/id/389A05CE-C2C1-4C31-9E8D-F0F9C1CBC1FD |
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taxon LSID |
lsid:zoobank.org:act:389A05CE-C2C1-4C31-9E8D-F0F9C1CBC1FD |
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scientific name |
Quasicalathus Schmidt & Will |
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gen. nov. |
Genus Quasicalathus Schmidt & Will gen. nov.
Type species.
Quasicalathus conservans Schmidt & Will, sp. nov., fossil species from the Eocene Rovno amber, herein designated.
Species included.
Three fossil species from Eocene amber deposits of Central Europe:
Quasicalathus agonicollis Schmidt & Will, sp. nov. (Baltic amber).
Quasicalathus conservans Schmidt & Will, sp. nov. (Rovno amber).
Quasicalathus elpis ( Ortuño & Arillo, 2009), new combination (Baltic amber).
Diagnostic characters.
Taxon with characteristics of Calathina and Calathus , respectively, as defined by Lindroth (1956) and Ball and Nègre (1972). The combination of the following character states defines the group:
Head: normal for Calathina, not thickened (Figs 24 View Figures 18–24 , 41 View Figures 39–46 , 81 View Figures 81–89 ); mandibles normal for Calathina, not broadened, not elongated (Figs 2 View Figures 1–5 , 52 View Figures 52–57 ); eye size averaged for Calathina, normally protruded (Figs 24 View Figures 18–24 , 41 View Figures 39–46 ); antennae pubescent from fourth antennomere (Fig. 20 View Figures 18–24 ); mentum tooth simple or slightly truncated at tip, with two fine setae near its base (Figs 52 View Figures 52–57 , 82 View Figures 81–89 ); submentum with two setae each side in normal position, with the internal setae robust and the external setae markedly short and thin (Figs 31 View Figures 31–33 , 52 View Figures 52–57 , 84 View Figures 81–89 ).
Prothorax: pronotal shape subquadrate ( “calathoid” form; Figs 3 View Figures 1–5 , 14 View Figures 13–17 , 34 View Figures 34–38 , 42 View Figures 39–46 , 50 View Figures 47–51 , 58-60 View Figures 58–60 , 63 View Figures 61–64 , 64 View Figures 61–64 , 73 View Figures 73–77 , 78 View Figures 78–80 ), slightly or moderately constricted toward base, with lateral margin straight or slightly concave before base, and with basolateral angles slightly or moderately obtuse (Figs 9 View Figures 6–12 , 14 View Figures 13–17 , 25 View Figures 25–30 , 42 View Figures 39–46 , 50 View Figures 47–51 , 63 View Figures 61–64 , 64 View Figures 61–64 , 74 View Figures 73–77 , 78 View Figures 78–80 ); basolateral angles not protruded posteriorly; basal margin beaded laterally (level of basolateral angles); basolateral seta situated at margin (Figs 9 View Figures 6–12 , 14 View Figures 13–17 , 20 View Figures 18–24 , 25 View Figures 25–30 , 42 View Figures 39–46 , 50 View Figures 47–51 , 66 View Figures 65–72 , 74 View Figures 73–77 ); pronotal disc with sculpticells of microsculpture transverse, very narrow (magnification 80 ×). Prosternum impunctate, smooth, prosternal process with or without apical bead (Figs 37 View Figures 34–38 , 38 View Figures 34–38 , 51 View Figures 47–51 , 75 View Figures 73–77 , 85 View Figures 81–89 ).
Pterothorax: elytra slender, ovate, glabrous, humeral tooth absent; basal bead moderately or markedly concave with humeral angle +/- markedly protruded anteriorly (Figs 9 View Figures 6–12 , 14 View Figures 13–17 , 25 View Figures 25–30 , 34 View Figures 34–38 , 47 View Figures 47–51 , 58 View Figures 58–60 - 61 View Figures 61–64 , 66 View Figures 65–72 , 74 View Figures 73–77 , 78 View Figures 78–80 ); epipleuron without plica (Fig. 53 View Figures 52–57 ); striae slightly to moderately deeply engraved, with punctures evident (Figs 25 View Figures 25–30 , 27 View Figures 25–30 , 58 View Figures 58–60 ); intervals flat to moderately convex; parascutellar seta present (Figs 14 View Figures 13–17 , 66 View Figures 65–72 , 74 View Figures 73–77 ); third interval with a single rather short, thin discal seta situated near the end of the apical elytral 2/3, adjoining second stria (Figs 11 View Figures 6–12 , 12 View Figures 6–12 , 16 View Figures 13–17 , 27 View Figures 25–30 , 29 View Figures 25–30 ; but see comments to the redescription of Q. elpis , below), with surroundings of setigerous puncture not depressed; external intervals without setae; intervals with sculpticells of microsculpture transverse, very narrow, narrower than on pronotum (Fig. 26 View Figures 25–30 ; magnification 100 ×, elytra appearing polished at 40 ×). Metepisternum elongate (Figs 4 View Figures 1–5 , 62 View Figures 61–64 , 83 View Figures 81–89 ). Hindwings fully developed.
Legs: length average for Calathina, neither markedly slender nor particular robust (Figs 4 View Figures 1–5 , 7 View Figures 6–12 , 30 View Figures 25–30 , 36 View Figures 34–38 , 49 View Figures 47–51 , 62 View Figures 61–64 ); male protarsomeres dilated; mesocoxa with a single ridge seta; metacoxa trisetose, with anterior seta large and with the two posterior setae small and thin, one located near external, one near internal margin (Figs 54 View Figures 52–57 , 67 View Figures 65–72 , 86 View Figures 81–89 ; but see comments to the redescription of Q. elpis below); metatrochanter with seta present (but see comments to the redescription of Q. elpis , below); metafemur with two setae on ventral surface, and with dorsoapical setae present; metatibia in male not densely pubescent; tarsi without pubescence or wrinkles on dorsal surface; meso- and metatarsomeres I-IV without external and internal lateral grooves; fifth tarsomeres with a single pair of dorsal setae, and with two pairs of ventral setae; claws pectinate (Fig. 8 View Figures 6–12 ).
Abdomen: ventrites smooth aside from normal setation; apical ventrite in both sexes with one pair of seta near apical margin (Fig. 53 View Figures 52–57 ).
Female genitalia (Figs 55-57 View Figures 52–57 , 76 View Figures 73–77 , 77 View Figures 73–77 ): basal gonocoxite about two times longer than apical gonocoxite; apical gonocoxite short, sickle-shaped, with one ensiform seta at dorsal and two ensiform setae at external margin, and with sensory pit large, well-developed, with two setae; basal gonocoxite without setae near apical margin; bursa copulatrix not markedly sclerotized.
Male genitalia (Figs 43-46 View Figures 39–46 , 68-72 View Figures 65–72 , 80 View Figures 78–80 , 87-89 View Figures 81–89 ): aedeagus right side ventral in repose; right paramere styloid with distal portion very long and slender, not terminated in a distinct apical hook; left paramere ovoid; median lobe with long apical lamella, without apical disc.
Etymology.
The name of the new subgenus is derived from the Latin conjunction “quasi” (like; as it were) and the name of the ground beetle genus Calathus , and thus refers to the morphological similarity to representatives of this genus.
Recognition and systematic placement within Sphodrini .
Presence of a styloid right paramere (an apomorphic character state within Sphodrini ) differentiates Quasicalathus gen. nov. from Atranopsina and Synuchina. Additionally, Quasicalathus lacks the stridulation organ that is an autapomorphy for Atranopsina ( Casale 1988). Presence of well-developed sensory pit of the apical gonocoxite (plesiomorphic state) differentiates Quasicalathus from Synuchina ( Casale 1988) and Dolichina sensu Sciaky and Facchini (1997), Sciaky and Wrase (1998) and Hovorka (2017b). Aedeagus with right side ventral in repose (right paramere styloid, left paramere ovoid; plesiomorphic state) differentiates Quasicalathus from Pristosiina. The combination of the following characters states places Quasicalathus outside of Sphodrina sensu Casale (1988): Mentum tooth not bifid (plesiomorphic state); antennae pubescent from fourth antennomere (plesiomorphic state); tarsomeres without pubescence and smooth on dorsal surfaces (plesiomorphic state); claws pectinate (symplesiomorph with Sphodrini except Atranopsina, reversed in some Sphodrina); aedeagal median lobe slender with long terminal lamella. The shape of the aedeagal median lobe and its terminal lamella is rather variable within Calathina, Dolichina and Synuchina ( Lindroth 1956, Habu 1978, Casale 1988).
Based on the overall similarity in external and genitalic characters the new, fossil genus Quasicalathus strongly resembles extant species of subtribe Calathina and genus Calathus (see next section). However, as it was comprehensively discussed by Schmidt and Will (2020), monophyly of Calathina is supported by molecular data ( Ruiz et al. 2009, 2010) while Calathus seems to be paraphyletic, and morphological data supporting Calathina monophyly are currently unknown. As a consequence, the definite, evidence-based, placement of fossil Quasicalathus species in this subtribe is currently impossible. What can be stated regarding the systematic placement of this taxon is the following:
Quasicalathus is included in the "P clade" of Ruiz et al. (2009) based on the shared presence of the markedly styloid right paramere, which is most likely an autapomorphy of this clade. Atranopsina and all but one outgroup, Zabrini, are characterized by much shorter parameres. The styloid right paramere shows a pattern of homoplasy across carabids and is considered a separate transformation in Zabrini as this group has not been shown to be the sister group to Sphodrini in relevant phylogenetic analyses (Ruiz et al. 2009, Gomez et al. 2016).
Quasicalathus is not a member of Synuchina, Dolichina or Pristosiina, as each of these sphodrine subtribes is characterized by respective autapomorphic states that are not present in the fossil specimens.
Quasicalathus is not a member of Sphodrina sensu Casale (1988) because each of the genera affiliated to this subtribe is characterized by at least one autapomorphic state that is not present in Quasicalathus (see above).
Given the lack of apparent morphological synapomorphies for subtribe Calathina and the genus Calathus there is currently no evidence that places Quasicalathus within, or as sister of, any one of these clades.
Fossils are basic for understanding the evolutionary history of species groups and fossil specimens are critical for time calibration of phylogenetic hypotheses. Therefore, in order to prevent misleading interpretations-e.g., the incorrect assignment of fossils that lack evidence of their placement-we propose the systematic position of Quasicalathus using a conservative, synapomorphy-based approach. This requires establishing the genus without a certain position within the sphodrine "P clade" of Ruiz et al. (2009), i.e., Sphodrini , informal group P clade, incertae sedis.
Recognition with respect to Calathina.
The overall similarity of Quasicalathus gen. n. with species of the genus Calathus makes it necessary to provide a detailed differential diagnosis of the new genus. Recently, Schmidt and Will (2020) presented an overview to the diagnostic characters of the currently accepted genera and subgenera placed within Calathina, and respectively Calathus , sensu Hovorka (2017a). The Eocene Quasicalathus differs from all calathine species groups by presence of a single elytral discal seta (but see Remarks section to the redescription of Calathus elpis , below). All but one Calathina are characterized by presence of at least two elytral discal setae, while the elytra of Tachalus Ball & Nègre lacks discal setae. Quasicalathus additionally differs from all calathine taxa, with the exception of Bedelinus Ragusa, by having a simple mentum tooth (entire instead of bifid), and trisetose metacoxa. Quasicalathus differs from all but the Himalayan Spinocalathus Schmidt by narrow transverse sculpticells of elytral microsculpture (nearly isodiametric in other Calathina). A slightly transverse pattern of elytral microsculpture is developed in some species of Denticalathus Schmidt, however, species of this group differ by pubescent third antennomere in addition to other characters mentioned above and below. Bedelinus and Spinocalathus differ from Quasicalathus additionally by removal of the pronotal laterobasal pronotal seta from the lateral margin, plus presence of lateral grooves on metatarsomeres I-IV. Quasicalathus differs from Spinocalathus by the short metepisterneum, and from Bedelinus and most Spinocalathus by presence of an apical hook on the right paramere. Quasicalathus shares meso- and metatarsomeres I-IV without external and internal lateral grooves with Iberocalathus Toribio, Lindrothius Kurnakov, some species of Calathus s. str., Denticalathus , and Neocalathus Ball & Nègre. However, species of these groups differ by presence of an apical hook on the aedeagal right paramere ( Lindrothius , Calathus s. str., Denticalathus , Neocalathus ) and by a markedly sclerotized spermatheca plus presence of a single ensiform seta along the external margin of the apical gonocoxite ( Iberocalathus ).
Here we hypothesize that i) presence of a single elytral discal seta and ii) presence of narrow transverse sculpticells of elytral microsculpture are synapomorphies of Quasicalathus gen. n.; the similarly developed pattern of elytral microsculpture in Spinocalathus and some Denticalathus are hypothesized as homoplasious as these groups share more derived patterns in some morphological features (e.g., bifid mentum tooth, bisetose metacoxa) together with other Calathina groups.
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