Balticeler kerneggeri Schmidt & Maddison, 2021

Schmidt, Joachim, Scholz, Stephan & Maddison, David R., 2021, Balticeler kerneggeri gen. nov., sp. nov., an enigmatic Baltic amber fossil of the ground beetle subfamily Trechinae (Coleoptera, Carabidae), Deutsche Entomologische Zeitschrift 68 (1), pp. 207-224 : 207

publication ID

https://dx.doi.org/10.3897/dez.68.66181

publication LSID

lsid:zoobank.org:pub:0D454AFB-9C31-42C3-A5B9-CD9E256C1F41

persistent identifier

https://treatment.plazi.org/id/32A6F70E-6731-490D-B563-73F3F79695B0

taxon LSID

lsid:zoobank.org:act:32A6F70E-6731-490D-B563-73F3F79695B0

treatment provided by

Deutsche Entomologische Zeitschrift by Pensoft

scientific name

Balticeler kerneggeri Schmidt & Maddison
status

sp. nov.

Balticeler kerneggeri Schmidt & Maddison sp. nov.

Type material.

Holotype: Male in Baltic amber, Coll. Friedrich Kernegger in the Centrum of Natural History, Hamburg (CeNak), with collection number " GPIH 04897, coll. Kernegger 1995/235". Size of the amber piece approx. 13 × 7 × 7 mm, irregularly cut, embedded in synthetic resin ( Hoffeins 2001) (Fig. 3 View Figures 1–7 ).

Preservation status: The amber is clear but pervaded by few flowlines dorsally of the embedded beetle fossil. The fossil is partly covered by milky coating on the ventral side of the body. The exoskeleton of the specimen and its negative imprint on the inclusion wall is well preserved and could therefore be visualized in detail using micro-CT (Figs 11-14 View Figures 11–14 ). In contrast, the aedeagus is poorly preserved inside the fossilized beetle body: it is strongly shrunken and deformed and therefore, its original shape and structure could not be determined.

Syninclusions: None.

Paratype 1: Male in Baltic amber, deposited in the Oregon State University Collection, with specimen number OSAC_0002900006. Size of the amber piece approx. 21 × 8 × 4 mm, irregularly cut (Fig. 4 View Figures 1–7 ).

Preservation status: The embedded beetle fossil is almost completely surrounded by flowlines. Head and prothorax are additionally covered by milky coating. Therefore, only small parts of the beetle body are visible using light microscopy (Fig. 4 View Figures 1–7 ). The exoskeleton of the fossil and its negative imprint on the inclusion wall are moderately well preserved and could therefore be imaged using micro-CT, but the head capsule is partly shrunken and displaced into the prothorax (Figs 26-28 View Figures 26–28 ). The aedeagus is rather well preserved inside the fossilized beetle body and could therefore be imaged using micro-CT in most details (Figs 27 View Figures 26–28 , 28 View Figures 26–28 , 32 View Figures 32–35 , 33 View Figures 32–35 , 35 View Figures 32–35 ); its external shape particularly near base, including the lateral lobes of the median lobe basal bulb, seem somewhat deformed (Fig. 33 View Figures 32–35 ), probably because the fossil specimen was embedded during an immature stage of its development; the apical apophysis of the right paramere is only partly preserved (Fig. 32d View Figures 32–35 ).

Syninclusions: None.

Paratype 2: Male in Baltic amber, Coll. Carsten Gröhn in the collection of the Geological-Palaeontological Institute of the University of Hamburg ( GPIH), now in the Centrum of Natural History, Hamburg (CeNak), with collection number " GPIH 5044, coll. Gröhn 8234". The amber piece was nearly triangularly cut with an edge length of about 33, 26, and 16 mm, and with width of 5 mm (Fig. 5 View Figures 1–7 ).

Preservation status: The amber is clear; large flowlines are attached to the left lateral side of the embedded beetle. The ventral surface of the beetle body is partly covered by milky coating. Antenna, legs, and dorsal surface of head are clear and thus well visible using light microscopy (Figs 6 View Figures 1–7 , 7 View Figures 1–7 ). The skeleton of the fossil beetle specimen together with its aedeagus is moderately well preserved and could therefore be imaged using micro-CT (Figs 29-31 View Figures 29–31 ); however, the basal portion of the aedeagus is partly decayed so that the parameres are preserved only with the more strongly sclerotized median parts (Fig. 34 a, b View Figures 32–35 ).

Syninclusions: 1 stellate hair, few dust particles.

Paratype 3: Specimen of unknown sex in Baltic amber, deposited in the Oregon State University Collection, with amber piece number OSAC_AMB0000387. According to the dealer (Marius Veta, Palanga) from whom the amber was purchased, this is most likely Baltic amber from the Yantarni mine, but there is a slight chance that it is Rovno amber. Size of the amber piece approx. 14 × 8 × 2 mm, irregularly cut (Fig. 8 View Figures 8–10 ).

Preservation status: The amber is clear but the ventral surface of the embedded beetle is completely covered by milky coating. Flowlines within the amber extend to each lateral side of the fossil. Most parts of the legs and the tip of the abdomen were abraded during polishing process and are thus lacking. Therefore, only the dorsal side of the beetle body is visible using light microscopy (Fig. 8 View Figures 8–10 ). The negative imprint of the fossil on the inclusion wall has low contrast in the X-ray analyses and therefore, certain details of external morphology could not be imaged and the sex of the specimen could not be assessed (Figs 36 View Figures 36–42 , 37 View Figures 36–42 ).

Syninclusions: One spider.

Paratype 4: Specimen of unknown sex in Baltic amber, deposited in the Oregon State University Collection, with amber piece number OSAC_AMB0000600. Size of the amber piece approx. 13 × 8 × 5 mm, cut into an approximately trapezoidal form (Fig. 9 View Figures 8–10 ).

Preservation status: The amber is pervaded by numerous air bubbles on the right side to the embedded beetle fossil; the latter is well visible from dorsal, left lateral and ventral sides using light microscope (Fig. 9 View Figures 8–10 ), but the head and thorax are covered by milky coating ventrally. The stone was very likely altered by autoclaving in order to reduce milky coating; this is evident from the blackened appendages of the beetle which are slightly deformed (particularly tibiae and tarsi), and from one of the synincluded Collembola which has a roasted appearance (for the effect of autoclaving on amber fossils see Hoffeins 2012). Very probably as a consequence of autoclaving, the negative imprint of the fossil on the inclusion wall has low contrast in the X-ray analyses; certain details of external morphology could thus not be imaged, and the genital armatures are not preserved (Figs 38-40 View Figures 36–42 ).

Syninclusions: One rove beetle ( Staphylinidae ), one springtail ( Collembola), remains of a second springtail.

Paratype 5: Specimen of unknown sex in Baltic amber, ex collectio Riccardo Sciaky (Milano), now preserved in the Museum für Naturkunde Berlin, with specimen number MB.I.8614. Size of the amber piece approx. 10 × 5 × 5 mm, polished into a somewhat bean-shaped piece (Fig. 10 View Figures 8–10 ).

Preservation status: Rather poor; head and ventral surface of the beetle fossil are completely covered by milky coating; in addition, flow lines of the amber surrounding the specimen (Fig. 10 View Figures 8–10 ). The negative imprint of the fossil on the inclusion wall has moderate low contrast in the X-ray analyses (Figs 41 View Figures 36–42 , 42 View Figures 36–42 ), and the genital armatures are not preserved.

Syninclusions: None.

Description.

Color: All specimens appear unicolored dark throughout, markedly shiny. No metallic reflection is visible.

Microsculpture: Head, pronotum and elytra with very finely impressed very small transverse meshes (visible at magnifications of > 80 ×).

Measurements and proportions, given as mean (min-max values):

Standardized body length 3.43 (3.01-3.77) mm.

PW/HW = 1.24 (1.21-1.28).

PW/PL = 1.09 (1.02-1.13).

PW/PWb = 1.39 (1.33-1.46).

PWb/PWa = 1.03 (0.97-1.08).

EW/PW = 1.66 (1.60-1.77).

EL/EW = 1.55 (1.50-1.59).

EL/FL = 2.18 (2.13-2.21).

EL/AedL = 2.36, 2.63 (paratypes 1, 2).

For individual measurements and proportions see Tables 2 View Table 2 , 3 View Table 3 .

Derivation of species epithet.

The species epithet is given in honor of Friedrich Kernegger, Hamburg, who found a piece of amber bearing a fossilized specimen of this extraordinarily interesting species more than 25 years ago.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Carabidae

Genus

Balticeler