Platypelochares electricus, Hernando & Szawaryn & Ribera, 2018

Hernando, Carles, Szawaryn, Karol & Ribera, Ignacio, 2018, A new species of Platypelochares from Baltic amber (Coleoptera: Limnichidae), Acta Entomologica Musei Nationalis Pragae 58 (1), pp. 17-20 : 18

Platypelochares electricus sp. nov.

( Figs 2–7 )

Type horizon. Middle Eocene (Lutetian).

Type locality. Baltic amber (secondary deposit, Gulf of Gdańsk area).The obtained FT-IR spectra are typical of Baltic amber,with the so called “Baltic shoulder” situated between 1190–1280 cm-1, and flanked by a strong absorbance peak at 1170 cm-1 (KOSMOWSKA- CERANOWICZ 2015) ( Fig. 1 ).

Type material. HOLOTYPE (unknown sex): Museum of Amber Inclusions, University of Gdańsk , ref. MAIG 5948 . Reference IR curves No. MAIG 5948 IR ( Fig. 2 ) and deposited in MAIG. Rectangular piece of clear amber, 12.0 × 6.4 × 3.0 mm, including the specimen of Platypelochares electricus sp. nov. plus one female specimen of Diptera : Ceratopogonidae : Brachypogon ( Brachypogon) sp. ( R. Szadziewski , personal communication, 2018) and one larva of Hemiptera ( Coccoidea ) ( Fig. 2 ). Venter clearly visible, of the dorsum only the impression in the amber is clearly visible. All legs are in their resting position (folded and inserted in the excavations of thorax and abdomen, see below) except the left middle leg, which is partially extended.

Description. Length 2.0 mm (measured along the ventral side), maximum width 1.4 mm. General shape roughly hemispherical, with posterior half slightly elongated ( Figs 2, 3 ).

Head retracted in prothorax, only frons visible ( Fig. 3 ). With a sharp carina bordering upper margin of eyes and clypeus, which is not visible. Antennae folded, not clearly visible.

Pronotum with a regular row of small tubercles in anterior part, extending laterally over the flattened lateral areas ( Fig. 4 ). Hypomera with a fossa covered with a white undifferentiated substance ( Figs 3, 5 ).

Elytral surface smooth and shiny, with a fine microreticulation, difficult to observe ( Fig. 6 ). Elytral pubescence perfectly preserved, all pores with setae ( Fig. 6 ). Margins explanate, visible from below ( Fig. 3 ). Apex of elytra with a small apical semicircular excavation, apparently not protruding in middle. Epipleura with punctation coarser and denser than on rest of ventral surface ( Fig. 3 ).

Ventral surface with double punctation: sparse large setiferous punctures, especially on metaventrite, and finer, equally sparse punctures ( Fig. 3 ). Surface of abdominal ventrites with rough punctation ( Fig. 7 ). Lateral margins of 2nd visible sternite glabrous and smooth, with a fine microreticulation, with excavations for reception of metatarsi ( Fig. 7 ). Last abdominal ventrite with an apical tuff of longer setae ( Fig. 3 ).

Ventral surface of trochanters and femora with strong, sparse punctation. Ventral surface of tibiae with a denser, coarser punctation, with setae. Articulation of meso- and metatarsi with tibia lateral, not terminal. Underside of tarsi with long, stiff setae ( Figs 5, 7 ).

Comparative notes. The presence of a row of tubercles on the pronotum places the new species within the P. trifidus group sensu RIBERA & HERNANDO (1999). Within this group, it can be separated from other species by the length of the row of tubercles, being longer than in P. latimargo Champion, 1923 and P. periculosissimus Ribera & Hernando, 1999 , but of similar extension to P. chinensis Yoshitomi, 2011. The body outline in dorsal view is also more similar to P. chinensis ( YOSHITOMI 2011), with the elytra slightly acuminate, not almost perfectly circular as in P. latimargo or P. periculossisimus. The elytral reticulation of P. electricus sp. nov. is, however, less marked than in P. chinensis, and the elytral pubescence is more sparse. The ventral punctation of P. electricus sp. nov. is also stronger and less dense than in all other species of the group.

Etymology. From the Latin electrum (= amber), adjective in nominative singular.

Figures

Figs 2–7.Amber inclusion of Platypelochares electricus sp. nov. 2 – amber piece with the studied specimen.3–7 – morphological details of P.electricus: 3 – ventral view; 4 – detail of the tubercle row on the pronotum (indicated by an arrow); 5 – detail of the ventral side of prosternum and right hypomeron, with the excavation (indicated by an arrow); 6 – lateral view; 7 – metacoxa and first four abdominal ventrites (arrow – lateral articulation of the tarsi).

Fig. 1. Fourier transformed infrared spectra (FT-IR) of the amber piece. Note the “Baltic shoulder” between 1190–1280 cm-1 (arrow).