Quasicalathus elpis ( Ortuno & Arillo, 2009) Schmidt & Scholz & Will, 2022

Schmidt, Joachim, Scholz, Stephan & Will, Kipling, 2022, Character analysis and descriptions of Eocene sphodrine fossils (Coleoptera, Carabidae) using light microscopy, micro-CT scanning, and 3 D imaging, Deutsche Entomologische Zeitschrift 69 (1), pp. 19-44 : 19

Quasicalathus elpis ( Ortuno & Arillo, 2009) comb. nov.

Figs 1-5 , 6-12 , 13-17 , 18-20 , 34-38 , 39-46 , 47-51 , 52-57 , 58-60 , 61-64

Calathus elpis Ortuño & Arillo, 2009: 56-60.

Type material.

Not studied; see Material and methods, above.

Remarks on original description and recognition.

The original description of the fossil species C. elpis is doubtful or confusing with respect to some important diagnostic characters, these are:

Elytra near middle with two setiferous pores in the 5 th interval. This pattern of chaetotaxy was not found in any of the fossil species we investigated. In contrast to what was presented by Ortuño and Arillo (2009), we believe that discal setae are absent in the 5 th interval of the C. elpis holotype specimen. It seems likely that the observation of the authors is based on a misinterpretation of micro-structures on the elytral surface of the fossil that are preservation artifacts and thus produce a false impression of existing setiferous pores. This interpretation is supported by the following three facts:

First, in the reconstruction drawing of the holotype specimen, Ortuño and Arillo (2009: 57, fig. 1d) figured a seta corresponding to each of the reconstructed setiferous pores in the 3 rd interval (these pores were found in all fossils we studied by us) but do not show those of the external intervals. Therefore, we believe that the authors may have observed structures in the external intervals that appear similar to (but not identical with) setiferous pores but do not bear setae.

Second, Ortuño and Arillo (2009: 57, fig. 1d) figured pore-like structures in the 6 th elytral intervals close to the 5 th striae but not in the 5 th interval (as reported in their description). Such setation pattern is unknown in sphodrine beetles, fossil or extant. Presence of setiferous pores in the 6 th elytral interval would also represent a markedly anomalous setation pattern, last but not least because the path of the cubital-1 nerve follows the 5 th elytral interval (Jeannel 1926).

Third, the character combination '3 rd interval uni-setose + one of the external intervals pluri-setose’ is absent in all other fossil and extant sphodrine species and therefore it is also very likely absent in C. elpis.

Ortuño and Arillo (2009: 58, fig. 2d) presented a reconstruction drawing of the C. elpis metacoxa that is bisetose in an irregular way: adjacent to the anterior seta an additional seta on the interior side of the posterior metacoxal surface was figured. Because this setation pattern is unknown in all Sphodrini and other Harpalinae, we believe that it is based on an erroneous interpretation of the actual coxal chaetotaxy of C. elpis. Although the majority of sphodrine species are characterized by bisetose metacoxae with one anterior and one posterior seta present, the posterior seta is always located near the external metacoxal margin. Very few Sphodrini possess a trisetose metacoxa with an additional seta interior of the external posterior seta, these include, some Atranopsina, Bedelinus of Calathina sensu Hovorka (2017a), Anchomenidius Heyden and Casaleius Sciaky & Wrase of Dolichina sensu Hovorka (2017b), and all the fossil species from Eocene amber that we investigated. In these extant and fossil taxa, the seta near the internal metacoxal margin is located at the same place as it was figured for C. elpis by Ortuño and Arillo (2009: 58, fig. 2d). Therefore, we believe that the external setiferous pore on posterior metacoxal area of C. elpis is present but was overlooked by the authors, probably because the seta was broken off or the view obscured, and that the metacoxa of C. elpis is actually trisetose as it is in all the other fossil specimens listed in the present study.

Ortuño and Arillo (2009: 58, fig. 2d) further presented a reconstruction drawing of the C. elpis metatrochanter that is asetose. However, the metatrochanters of the holotype specimen actually each are bearing a setiferous pore ( Ortuño pers. comm., 2009) as in the diagnosis of Quasicalathus gen. n. (see above).

In addition to the doubtful character states discussed above, the original description of C. elpis provides few indications that lead to recognition of specimens of this species without direct comparison to the holotype. The ten sphodrine specimens from Baltic amber available for us to study, belong to at least two different species of Quasicalathus , and all but one of the diagnostic characters we found to be relevant for these species are absent in the description presented by Ortuño and Arillo (2009). Our interpretation of C. elpis as a member of Quasicalathus gen. n. is based on the assumption that elytral and coxal chaetotaxy was misinterpreted by the authors of the species as discussed above and, additionally, on the following morphological features evident in the photographs of the holotype specimen provided by Ortuño and Arillo (2009: figs 1b, c): pronotal lateral margin moderately narrowed toward base, straight before laterobasal angles, with the latter moderately obtuse (instead of more rounded pronotal lateral margin with more obtuse laterobasal angles in the Baltic amber fossil species Q. agonicollis sp. nov.; see description below). Based on this character, we assume eight of the fossil specimens that are listed under Additional material (below) belong to C. elpis . As a consequence, the redescription of Quasicalathus elpis comb. nov. and information about additional morphological characters that we use to distinguish this species from other Eocene sphodrine species (see descriptions of the new fossil species, below) are based on investigation of these eight additional specimens.

Additional material.

Eight specimens, with the following identification numbers, collection data, preservation state, and syninclusions:

Groehn 4879. Male in Baltic amber, with specimen label data "Groehn 4879", deposited in Coll. Carsten Gröhn, Hamburg. Size of the piece approx. 15 × 15 × 4 mm (Fig. 1 ) .

Preservation status: The amber is clear but pervaded by numerous air bubbles; most details of external morphology of the embedded fossil are well visible using light microscope (Figs 2 , 3 ). Some parts of the exoskeleton (head, pronotum, elytral apex) are discoloured black. Using micro-CT, the fossilized beetle body yields moderate to low contrast so that parts of its external shape could only be coarsely imaged (Figs 34-37 ). The aedeagus is not preserved.

Syninclusions: Stellate hairs, additional plant remains, dust particles.

Groehn 7814. Male in Baltic amber, with specimen label data "Groehn 7814", deposited in Coll. Carsten Gröhn, Hamburg. Size of the piece approx. 35 × 17 × 9 mm (Fig. 5 ) .

Preservation status: The amber is pervaded by numerous flowlines and air bubbles and therefore; the embedded fossil is only visible ventrad and right laterad using light microscopy (Fig. 4 ). The exoskeleton of the fossil is moderately well preserved and important diagnostic characters could be imaged using micro-CT (Figs 38 , 41 , 42 ). The aedeagus is preserved in most parts (Figs 43-46 ), however, it was completely detached from the terminal abdominal segments during fossilization of the specimen. Most likely it moved through the abdomen and was finally wedged in the tight connection of meso- and metathorax (Figs 39 , 40 ) after drying out of the internal parts of the beetle.

Syninclusions: Stellate hairs, two Nematocera flies, one mite.

Groehn 7889: Female in Baltic amber, with specimen label data "Groehn 7889", deposited in Coll. Carsten Gröhn, Hamburg. The original size of the amber piece was approx. 35 × 23 × 10 mm and was separated into two pieces (Groehn 7889) in order to get better micro-CT scanning results. The size of the amber piece bearing the calathine fossil measures approx. 30 × 11 × 10 mm (Fig. 6 ) .

Preservation status: The amber is pervaded by an extend flowline attached to the beetle laterally, and a large air bubble is attached to its abdomen ventrally, but most external characters of the beetle are visible using light microscope (Figs 6 , 7 ). The exoskeleton of the fossil is well preserved and could be imaged to show most details using micro-CT (Figs 47 - 54 ) including the gonocoxites (Figs 55-57 ).

Syninclusions: Plant remains, dust particles.

Groehn 7962: Male in Baltic amber, with specimen label data "Groehn 7962", deposited in Coll. Carsten Gröhn, Hamburg. Size of the amber piece approx. 14 × 10 × 6 mm, irregularly cut and polished (Fig. 10 ) .

Preservation status: The amber is pervaded by numerous flowlines and air bubbles attached to the beetle body, mostly to its ventral surface; the fossil is therefore only partly visible using light microscope (Figs 9-12 ). Using micro-CT, the fossilized beetle body yields low contrast so that its external shape could only be coarsely imaged (Fig. 58 ). The aedeagus is not preserved.

Syninclusions: None.

CCHH 952. Female in Baltic amber, with specimen label data “CCHH952-2”, deposited in the collection of Christel and Hans Werner Hoffeins, Hamburg. Size of the piece approx. 39 × 15 × 7 mm (Fig. 15 ) .

Preservation status: The amber is clear in most parts, a single flowline is attached to the right side of the beetle body, which is clearly visible for most of its length using light microscope (Figs 13 , 14 ); head and abdomen are partly covered by a dirty coating ventrally. The amber was likely altered by autoclaving in order to reduce the milky coating. The results of this process are apparent from the blackened appendages of the beetle that are distinctly deformed (particularly tibiae and tarsi), and from one of the synincluded Nematocera that has a roasted appearance. For details on the effect of autoclaving on amber fossils see Hoffeins (2012). Using micro-CT, the fossilized beetle body yields a contrast so that its external shape could only be coarsely imaged (Fig. 59 ). This is likewise evidence of prior autoclaving of the piece.

Syninclusions: Two mites, one Brachycera fly, remains of two Nematocera flies, dust particles.

OSAC 265. Male in Baltic amber, with specimen label data “OSAC_2900265”, deposited in the Oregon State University Collection. The original size of the amber piece was 57 × 16 × 4 mm and was separated into three pieces in order to get better micro-CT scanning results. The size of the amber piece bearing the calathine fossil measures approx. 21 × 9 × 4 mm (Fig. 17 ).

Preservation status: The amber is clear in most parts, some flowlines are attached to the embedded fossil; latter is well visible in most parts of the body using light microscope (Figs 16 , 17 ). Using micro-CT, the fossilized beetle body yields low contrast and therefore, its external shape could only be coarsely imaged (Fig. 60 ). The aedeagus is not preserved.

Syninclusions: Large number of dust particles in each of the three pieces.

MAIG 76. Female in Baltic amber, with specimen label data “76” deposited in Museum of Amber Inclusions, University of Gdańsk, Poland. Size of the amber piece ca. 33 × 23 × 10 mm, irregularly cut (Fig. 18 ).

Preservation state: Moderately well preserved due to a large bubble and extensive milky coating attached to the left part of the fossil, resulting in a significant deformation of the beetle body (Fig. 61 ). A flowline and a corrosion crack are attached to the right side of the beetle body; the apex of the right elytron reaches the amber’s external surface due to a small cavity in the amber piece. Because the fossil yields moderately strong contrast during micro-CT scan, details of its external shape could be imaged apart from the ventral side of the head (Figs 61-63 ). The genitalic segments are not preserved.

Syninclusions: One tiny insect larva; several air bubbles.

GZG 16185 . Male in Baltic amber, with specimen label data "GZG BST 16185 " and “G633.G636”, deposited in Geoscience Museum, University of Göttingen, Germany (very probably ex coll. Königsberg). Size of the amber piece 15 × 8.5 × 6 mm, originally with seven polished edges, but fragmented into two pieces of about the same size, with one piece containing most parts of the fossil while the other contains the negative imprint of the left elytron (Fig. 19 ); the surface of the latter piece bears the inscription “G633.G636” .

Preservation state: Poorly preserved due to amber corrosion; several corrosion cracks pervade the amber surface; amber is markedly darkened with the embedded fossil hardly visible in most views; fossil is partly covered by flowlines, bubbles and milky coating. The fossilized beetle body yields low contrast during micro-CT scan, so that its external shape could only be very coarsely imaged (Fig. 64 ). The aedeagus is not preserved.

Syninclusions: Stellate hairs, dust particles.

Redescription.

Measurements see Table 2 .

SBL: 7.5-8.8 mm ( Ø 7.9 mm; n = 7).

Proportions: A3L/HL = 0.40-0.45 ( Ø 0.42; n = 11);

EyL/ HW(-) = 0.65-0.79 ( Ø 0.72; n = 15);

PW/HW(+) = 1.39-1.58 ( Ø 1.50; n = 8);

PW/PL = 1.26-1.33 ( Ø 1.29; n = 8);

PW/PWb = 1.03-1.13 ( Ø 1.10; n = 8);

PWb/PWa = 1.47-1.61 ( Ø 1.52; n = 8);

EW/PW = 1.53-1.64 ( Ø 1.29; n = 7);

EL/EW = 1.51-1.62 ( Ø 1.55; n = 7);

EpL/EpW = 1.47-1.60 ( Ø 1.55; n = 10);

EL/FL = 2.35-2.65 ( Ø 2.53; n = 7);

EL/AedL = 4.05 (n = 1).

Head: Microsculpture on disc consists of very small slightly irregular meshes (magnification 80 ×). In all other characters as described for the new genus, above.

Prothorax: Pronotal lateral margin moderately narrowed toward base, straight or slightly concave before laterobasal angles, angles slightly obtuse (Figs 3 , 9 , 14 , 34 , 42 , 50 , 58-60 , 63 , 64 ). Prosternal process with or without apical bead (Figs 37 , 38 , 51 ). In all other characters as described for the new genus, above.

Pterothorax: Elytra with basal margin markedly concave and humerus markedly protruded anteriorly; basal margin forming a slightly obtuse angle (100-115°) with lateral margin (Figs 3 , 9 , 14 , 34 , 47 , 58-60 , 61 ). Elytral striae moderately deeply engraved, intervals moderately convex. In all other characters as described for the new genus, above.

Female genital: Length of apical gonocoxite about 0.18 mm; shape see Figs 55-57 . In all other characters as described for the new genus, above.

Aedeagus: Length of median lobe about 1.23 mm; median lobe terminal lamella moderately long and more markedly narrowed just behind its base so that its left margin is markedly concave and its apex slender lingulate (Fig. 46 ); in lateral view, terminal lamella markedly bent ventrally (Figs 43-45 ; note that the intensity of ventral bending might also be an artefact of poor preservation). In all other characters as described for the new genus, above.

Differential diagnosis.

Quasicalathus elpis (in sense of this paper) differs from Q. agonicollis sp. nov. by larger body (SBL> 7 mm), less obtuse laterobasal angles of pronotum, more concave elytral basal margin, more markedly projected humeri, less obtuse humeral angle (<120°), longer apical gonocoxites and larger aedeagus. It differs from Q. conservans sp. nov. by the proportionally smaller aedeagus with terminal lamella bent ventrally (Figs 43-45 ); the left margin of the terminal lamella in dorsal view is significantly concave in Q. elpis (Fig. 46 ) but almost straight in Q. conservans sp. nov. (Fig. 88 ).

Figures

Figures 1 - 5. Quasicalathus elpis (Ortuno and Arillo 2009), light microscopic images of specimens " Groehn 4879 " (1 - 3.) and " Groehn 7814 " (4, 5.). 1, 5. General view of the amber pieces; 2. Ventral side of head (the white arrow points to the mentum tooth; note that the mentum is somewhat detached from the head capsule); 3. Pronotum and anterior part of elytra showing the markedly concave basal margin and projected humeri; 4. Right lateral view of body.

Figures 6 - 12. Quasicalathus elpis (Ortuno and Arillo 2009), light microscopic images of specimens " Groehn 7889 " (6 - 8.) and " Groehn 7962 " (9 - 12.). 6, 10. General view of the amber pieces (in Fig. 6, only the part of the large amber piece bearing the Quasicalathus fossil is shown); 7. Ventral side of body; 8. Left mesotarsi iv + v; 9. Pronotum and anterior part of elytra, left side of body; 11, 12. Medial part of left elytron (Fig. 12 shows the enlarged part of the elytron marked by the white frame in Fig. 11; the white arrow points to the insertion of the discal seta). Abbreviations: bs - insertion of the pronotal laterobasal seta; hm - humerus; I-VIII - elytral intervals 1 - 8.

Figures 13 - 17. Quasicalathus elpis (Ortuno and Arillo 2009), light microscopic images of specimens " CCHH 952 " (13 - 15.) and " OSAC 269 " (16, 17.). 13. Dorsal view of body; 14. Pronotum and anterior part of elytra showing the markedly concave basal margin and projected humeri (the white arrows point the insertion pores of the parascutellary setae); 15, 17. General view of the amber pieces; 16. Posterior part of left elytron (the white arrow points to the insertion of the discal seta).

Figures 18 - 24. Quasicalathus, light microscopic images of Q. elpis Ortuno & Arillo, 2009 (18 - 20.) and Q. agonicollis sp. nov. (21 - 24.). 18. General view of the amber piece " MAIG 76 " (only that part of the large amber piece bearing the Quasicalathus fossil is shown; the fossil is widely covered by milky coating); 19. General view of the two fragments of specimen " GZG 16185 "; the left one bears only the negative imprint of the left elytra on the inclusion wall; 20. Right anterior part of body of specimen " GZG 16185 " showing part of head, pronotum and humerus; 21, 22. General view of the amber piece " GZG 16188 " (21. With fossil in dorsal view; 22. In ventral view); 23. Anterior part of specimen " GZG 16188 "; 24. Head of specimen " GZG 16188 ". Abbreviations: a 1 - a 6 - antennomeres 1 - 6; as - anterior supraorbital seta; bs - pronotal laterobasal seta; ms - pronotal lateral seta; ps - posterior supraorbital seta.

Figures 34 - 38. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of specimens " Groehn 4879 " (34 - 37.) and " Groehn 7814 " (38.). 34. Dorsal aspect; 35. Right lateral aspect; 36. Ventral aspect; 37, 38. Prosternum and basal portions of prolegs. Abbreviations: cx - procoxa; fm - profemur; psp - prosternal process; tr - protrochanter.

Figures 39 - 46. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of specimen " Groehn 7814 " using different grey scales of the Amira software. 39. Dorsal aspect; 40. Lateral aspect. The displaced aedeagus (highlighted by red colour) was separated by the segmentation function of Amira software in Figures 39 and 40; 41. Head (the arrows point to the insertions of the supraorbital setae); 42. Pronotum (the arrows point to the insertions of the lateral setae); 43 - 46. Remains of the aedeagus in right lateral aspect (43.); Left lateral aspect (44.); Left lateral aspect (45.); Dorsal aspect (46.). The distal margins of the styloid apophysis of the right paramere in Fig. 43 and the lobate apophysis of the left paramere in Fig. 45 are highlighted by red dotted lines. Abbreviations: bb - basal bulb of aedeagal median lobe; os - distal ostium; pml - left paramere; pmr - right paramere; tl - terminal lamella of median lobe.

Figures 47 - 51. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of specimen " Groehn 7889 ". 47. Dorsal aspect; 48. Left lateral aspect; 49. Ventral aspect; 50. Pronotum (the arrows point to the insertions of the lateral setae); 51. Prosternum (for better view the prolegs are partly removed using the clipping plane function of Amira software. Abbreviations: cx - procoxa; psp - prosternal process; tr - protrochanter.

Figures 52 - 57. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of specimen " Groehn 7889 ". 52. Head, ventral aspect (the arrows point to the insertions of the setae near base of mentum tooth and on submentum); 53. Abdomen, left lateral aspect (the arrows point to the insertions of the setae on ventrites IV, V, and VI); 54. Metacoxal area (the arrows point to the insertions of the coxal setae); 55. Apical gonocoxites, ventral aspect; 56. Apical gonocoxites, dorsal aspect; 57. Gonocoxites and remains of the bursa copulatrix (the latter was highlighted by red colour using the segmentation function of Amira software). Abbreviations: at - apical tooth of retinacle; kes - metathoracic katepisternum; cx - metacoxa; cxp - metacoxal plate; des - dorsal ensiform setae; ep - elytral epipleuron; fm - metafemur; gu - gula; mdl - left mandible; gx 1 - basal gonocoxite; gx 2 - apical gonocoxite; mdr - right mandible; mo - molar; mt - mentum; sp - sensory pit; tr - metatrochanter; ves - ventral ensiform setae; v 3, v 4, v 5, v 6 - ventritres III, IV, V, VI.

Figures 58 - 60. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of the dorsal aspects of specimens " Groehn 7962 " (58.), " CCHH 952 " (59.), and " OSAC 265 " (60.).

Figures 61 - 64. Quasicalathus elpis (Ortuno and Arillo 2009), volume rendering of specimens " MAIG 76 " (61 - 63.) and " GZG 16185 " (64.); 61. Dorsal aspect; 62. Right lateral aspect; 63, 64. Pronotum (the pronotal outline on left side is highlighted by dotted line in Fig. 64).

Figures 81 - 89. Quasicalathus conservans sp. nov., volume rendering of the holotype. 81. Head, dorsal aspect (the arrows point to the insertions of the supraorbital setae); 82. Head, ventral aspect; 83. Left external part of metathorax, ventral view; 84. Submentum (the arrows point to the insertions of the four lateral setae); 85. Posterior part of prosternum and procoxae; 86. Posterior part of metasternum and metacoxae; 87 - 89. Preserved remains of the aedeagus (87. Right lateral aspect; 88. Dorsal aspect; 89. Left lateral aspect). Abbreviations: bb - basal bulb of aedeagal median lobe; ce - compound eye; cxp - metacoxal plate; eph - partly evaginated lobes of endophallus; gu - gula; mem - metepimeron; mes - metepisternum; mtt - mentum tooth; mv - metaventrite; pcx - procoxa; pmr - preserved distal part of right paramere of aedeagal median lobe; psp - prosternal process; sc - scutellum; sps - setae of sensory pit; tl - terminal lamella of aedeagal median lobe.