Malthodes (s. str.) vallombrosa Parisi & Fanti, 2024

Parisi, Francesco & Fanti, Fabrizio, 2024, A new fossil Malthodes (Coleoptera: Cantharidae) from the Baltic amber Lagerstätte, Ecologica Montenegrina 73, pp. 100-105 : 101-105

Malthodes (s. str.) vallombrosa Parisi & Fanti sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:657B6725-30B0-41E2-9159-FCF2E6DA14B4

( Figs. 1–2 )

Holotype. Male , inclusion in Baltic amber, deposited in the University of Molise - Unimol ( Pesche , Isernia, Italy), with catalog number Unimol AAA008FP.

Etymology. The specific epithet refers to the Vallombrosa Forest (Tuscany, Italy), in reference to the fact that the first Author has studied in detail and for a long time the biological-forestry aspects of this protected area. Noun in apposition.

Locality and horizon. Baltic Sea Coasts. Baltic amber: Middle Eocene (Lutetian) (47.8–41.2 Ma) to late Eocene (Priabonian) (37.8–33.9 Ma).

Differential diagnosis. The new species is morphologically extremely similar to Malthodes (s. str.) giannii Parisi & Fanti, 2020 from Baltic amber, with the latter having the last tergite (tg10) broader, with folded sides (the sides of the last tergite are not folded in M. vallombrosa sp. nov.) and extremely less globose ( Parisi & Fanti, 2020). As regards Bitterfeld amber, Malthodes andreasiabelei Fanti, 2019 differs from the new species due to last sternite (st9) noticeably curved ( Fanti, 2019a, 2019b).

Syninclusions. Detritus particles.

Systematic placement. The short elytra, the head rounded behind the eyes, small body size, the last maxillary palpomere globular and distally pointed, and the last abdominal segments strongly modified clearly place this species in the genus Malthodes Kiesenwetter, 1852 ( Kiesenwetter, 1852; Wittmer, 1970; Brancucci, 1980; Liberti, 2011, 2015, 2017).

Description. Adult, winged (brachelytrous), slender, male defined on the basis of the last abdominal segments strongly modified. Total body length: 2.8–2.9 mm. Antenna length: about 2.1 mm. Entirely blackish without yellow spots on elytra.

Head exposed, slightly elongated, rounded behind eyes, with dense and shallow punctuation. Eyes large, rounded, prominent, inserted in lateral-upper part of the head. Maxillary palpi 4-segmented, with last palpomere globular and distally pointed. Labial palpi 3-segmented, last palpomere globular and distally pointed. Antennae filiform, 11-segmented, densely setose, very short, almost reaching elytral apex and middle of abdomen; antennomere I elongate, robust, club-shaped; antennomere II robust, enlarged medially, about 1.4 times shorter than antennomere I; antennomere III slightly shorter and slightly less sturdier than antennomere II; antennomere IV longer than antennomere III; antennomeres V–X sub-equal, slightly shorter than antennomere IV; antennomere XI elongated, with rounded apex. Pronotum transverse, wider than head, surface finely punctate and covered with very short setae, anterior margin straight, posterior margin straight and bordered, sides rather rounded. Elytra short, approximately reaching the half of abdomen, wider than pronotum, covered with short setae, parallel-sided, rounded at apices. Metathoracic wings transparent, noticeably surpassing elytra and last abdominal segments. Legs short and robust, densely pubescent; coxae elongate; trochanters robust with rounded apex; femora enlarged and rather straight; pro- and mesotibiae approximately as long as pro- and mesofemora, metatibiae slightly longer than metafemora, thin, cylindrical, with spur apically; tarsi 5-segmented, pubescent; tarsomeres I robust, slightly elongate; tarsomeres II shorter than tarsomeres I; tarsomeres III short, triangular-shaped; tarsomeres IV feebly bilobed and robust; tarsomeres V elongate and slender; claws simple. Metasternum elongate. Sternites transverse, wide and pubescent. Last tergite (tg10) with broad and not particularly long lobe, not folded at sides, slightly folded towards sternites, flat at base and almost globular apically, with apical margin straight and extremely slightly concave medially; last sternite (st9) elongate, very slightly curved, flat and apically forked (with lobes short, robust, not particularly deeply forked). Aedeagus not visible.

Remarks. The yellow amber piece is rectangular in shape, with approximately dimensions of 19 × 11 × 3 mm and weights 0.6 grams. The inclusion is complete and well visible. The surface has some very superficial fractures. The female of this species is currently unknown.

Discussion

Baltic area, where this amber is preserved was very rich in species of Malthodes in the Eocene. The evolution of the genus apparently began after or near the mass extinction that occurred 66 Ma, but most likely before Eocene ( Fanti, 2021; Fanti & Pankowski, 2024). In the present-day Baltic region, only few species of Malthodes are known ( Kazantsev & Brancucci, 2007), probably due to the cold temperatures ( Erwin, 2009; Pankowski & Fanti, 2023). The fossil records of Cantharidae and Malthodes have suggested or helped us understand various biological aspects. For example, orography is not always responsible for the specific diversification that we observe today in Malthodes ( Wittmer, 1970; Liberti, 2011, 2015, 2017), as in the Eocene forests, mountains were absent or poorly present (Sadowski, 2017; Sadowski et al., 2017). A fossil representative of Malthodes have extruded cuticular abdominal vesicles ( Fanti & Pankowski, 2018) and therefore have likely evolved alkaloids as defense strategies, like the other subfamilies of Cantharidae (e.g., Moore & Brown, 1978; Eisner et al., 1981). This would suggest that the yellow and rounded spots at the apex of the elytra of these insects, could be implicated in some way in aposematic mimicry, however the fossils Malthodes rarely present these colored spots, and it is not well known whether this is due to mere taphonomic fact or because they were originally missing ( Fanti, 2021). The “defense strategies” of the vesicles could, however, be hypothesized together with other functions, for example in pheromones. This appears unlikely because in others Cantharidae , such as in the subfamily Silinae Mulsant, 1862 , it is well known that some depressions and pronotal modifications are implicated in the release of pheromones and secretions (e.g., Ramsdale, 2002; Eberhard, 2006). Each new small and apparently unimportant species can actually allow us to discover many aspects of today's life, of the environment and of the relationships between various organisms, helping us in environmental conservation and therefore in the development of better economic, health strategies, etc.,.

Acknowledgments

We are very grateful to Marius Veta (Palanga, Lithuania) for providing us with this interesting specimen for science. We also are indebted to Giovanni Parisi (Alife, Caserta, Italy) for the excellent drawing of the new species’ abdominal segments. Two anonymous reviewers were extremely helpful in improving our document.

References

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Figures

Figure 1. Malthodes (s. str.) vallombrosa sp. nov. in Baltic amber, holotype: (A) habitus, lateral view; (B) details of forebody, lateral view. Scale bars = 0.5 mm.

Figure 2. Malthodes (s. str.) vallombrosa sp. nov. in Baltic amber, holotype: (A) detail of last tergite; (B) detail of last sternite; (C) reconstruction of last abdominal segments, lateral view. Scale bars = 0.2 mm (for A and B), 0.1 mm (for C).