Tychobythinus villasmundi Sabella, Amore and Nicolosi, 2019

Sabella, Giorgio, Amore, Elena & Nicolosi, Giuseppe, 2019, A new troglobitic Tychobythinus from Sicily (Coleoptera, Staphylinidae, Pselaphinae), Zootaxa 4567 (2), pp. 379-386 : 382-385

Tychobythinus villasmundi Sabella, Amore and Nicolosi sp. nov.

( Figs. 5–13 )

Type material. Holotype: ITALY: Sicily Region: Melilli (SR), Villasmundo Cave , 16.IX.2017, 1 ♂, G. Nicolosi leg. ( DBUC) . Paratypes: ITALY: Sicily Region : 2 ♀♀, same data of holotype ( DBUC) ; 1 ♀, same locality, 31.V.2018, G. Nicolosi leg. ( DBUC) ; 2 ♀♀, same locality, 05.VII.2018, G. Nicolosi leg. ( DBUC) ; 3 ♀♀, same locality, 29.VII.2018, G. Nicolosi leg. ( DBUC) ; 2 ♀♀, same locality, 11.X.2018, trap 7, G. Nicolosi leg. ( DBUC) ; 1 ♂ and 2 ♀♀, same locality, 26.X.2018, trap 7, G. Nicolosi leg. ( DBUC) ; 1 ♀, same locality, 27.XI.2018, trap 7, G. Nicolosi leg. ( DBUC) .

Description. Male: Length 1.25–1.30 mm, apterous and anophthalmous. Entirely pale brown with lighter antennae, palpi, and legs. Pubescence consists of long and flattened setae (length: 0.07–0.08 mm) on head, pronotum, elytra and abdomen, other suberect shorter setae (length: 0.03–0.04 mm) on antennae, and legs, and thin fluff on apical segment of maxillary palpi.

Head ( Figs. 6–7 ) wider (0.30 mm) than long (0.235–0.240 mm) slightly narrower than pronotum. Frontal lobe wider (0.15 mm) than long (0.075 mm) with subparallel, protruding and sharp sides; antennal tubercle protruding. Frons between antennal tubercles with large median sulcus reaching the anterior edge of vertexal foveae. Sides of frontal region with some punctures. Clypeal carina well-defined, equally visible in dorsal as well in lateral view, extends to ocular region. Tempora rounded, convex occipital region traversed by median longitudinal sulcus reaching over posterior edge of vertexal foveae, late wide and well-impressed. Gular region ( Figs 8–9 ) behind labium with deep and broad impression margined posteriorly by transverse ridge projecting on each side of head. This ridge with long and acute median process, projecting ventrally, and bearing tuft of setae on the tip. Base of the gular region with two long and sturdy medians bristles. Antennae ( Fig. 10 ) 0.635–0.640 mm long, scape more than 3.5 times longer (0.175–0.185 mm) than wide (0.05 mm), narrowed and flattened with protruding and sharp medial margin in basal third, wider in middle. Pedicel ovoid, slightly asymmetric, about one and a half times longer than wide, slightly tighter than scape, and distinctly wider than funicular segments. Antennomere III longer than wide and slightly narrowed at base; antennomere IV as long as wide, antennomere V longer than wide, antennomeres VI–VII subequal and as long as wide, antennomere VIII wider than long. Antennal club consisting of last three antennomeres which are broaden progressively from IX to XI. Antennomere IX slightly wider than long, antennomere X distinctly wider than long, antennomere XI distinctly longer than wide and twice as long as combined length of antennomeres IX and X. Maxillary palpi with palpomere II elongated and gradually expanded from base to apex, its surface covered by 4–6 tubercles concentrated in the distal portion. Palpomere III slightly longer than wide, its surface with 2–3 tubercles; last palpomere about 4 times as long (0.24 mm) as wide (0.06 mm), widest in basal third, lateral margin slightly curved and sinuate in middle.

Pronotum slightly wider (0.31 mm) than long (0.30 mm), widest near basal third, anteriorly slightly tapered with sinuates sides, posteriorly more tapered with straight sides. Its dorsal surface shiny with some rare and fain punctures. Pleural carina oblique, well-defined. Two well impressed antebasal lateral fovea linked by the antebasal sulcus. Tegument between pronotal posterior margin and antebasal sulcus rough, it makes difficult to recognize median antebasal fovea. Metaventrite with median egg-shaped impression beginning from its posterior margin and extending just before mesocoxal cavities, and bearing for its entire length a median longitudinal carina. Base of mesocoxal cavities with pubescent pit on each side.

Elytra distinctly wider (0.55 mm) than long (0.49 mm), convex, sides slightly rounded from base to the apex, widest near middle. Humeral calli strongly reduced. Dorsal surface shiny with only some superficial punctures. Each elytron with two basal foveae, subhumeral fovea well-defined. Both, marginal and sutural striae reaching elytral apex, discal striae lacking.

Abdomen normally shaped without particular characters.

Legs relatively long and thin. Protrochanters with 1–2 tubercles on ventral surface, protibiae slightly flattened and sinuate in distal third, tarsomere II of protarsi slightly dilated. Meso and metatrochanters simple; femora simple, mesotibiae simple, length of metatibiae: 0.45–0.46 mm, slightly enlarged and sinuate in the distal third.

Aedeagus ( Fig. 12 ) 0.24–0.25 mm long, ovoid with relatively short parameres, that are convergent and with narrow apex, each bearing two subapical setae. Internal sac with 2 big and long teeth and 3 smaller spines.

Female: Similar to male ( Fig. 5 ), length 1.25–1.45 mm, head slightly wider (0.25–0.26 mm) than long (0.23– 0.24 mm), gular region unmodified, slightly convex. Maxillary palpi with surface of palpomere II covered by 12– 16 tubercles ( Fig. 11 ). Metaventrite lacking median impression; legs with protibiae, tarsomere II of protarsi, and metatibiae unmodified. Telisternite as in Fig. 13 .

Discussion. T. villasmundi sp. nov. differs from all other Tychobythinus species by its aedeagal and exoskeleton features. However, it shows affinities with Tychobythinus species from North Africa which belong to two distinct groups ( Sabella et al. 2014). Since their external morphology is closely related to their biology, it is not necessary they really represent two homogeneous phyletic lineages.

The aedeagus of T. villasmundi sp. nov. is comparable with the species belonging to the Tychobythinus algiricus group ( Sabella et al. 2014; Chiasmatobythus sensu Jeannel 1956 ), especially to T. algiricus ( Raffray 1871) , which is widespread in the Maghreb ( Tunisia, northern Algeria and Morocco). However, all the species in this group are macro or microphthalmous, whereas T. villasmundi is anophthalmous.

Because of troglobitic adaptations, T. villasmundi can be also compared with the species belonging to the Tychobythinus theryi group ( Sabella et al. 2013; Anopsibythus sensu Jeannel 1956 ) and, especially with the wingless and eyeless T. theryi ( Guillebeau 1894) , known only from three females from Saint Charles (northern Algeria), and T. normandi ( Jeannel 1956) , which is known only from a single male from Philippeville (old name of Skikda) in northern Algeria.

Tychobythinus villasmundi sp. nov. can be easily distinguished from T. theryi by its shiny tegument of dorsal surface (slightly but distinctly punctuate in T. theryi ), the wider frontal lobe (0.15 mm in T. villasmundi sp. nov. versus 0.125–0.13 mm in T. theryi ), longer antennae (0.63–0.64 mm in T. villasmundi sp. nov., versus 0.55–0.56 mm in T. theryi ), and by the presence of less tubercles on the palpomere II (12–16 in T. villasmundi sp. nov. against 24–30 in T. theryi ).

Tychobythinus villasmundi sp. nov. differs from T. normandi mainly by the features on the tempora (rounded in Tychobythinus villasmundi , angulated and dug in T. normandi ). From both species the new species differs by the structure of aedeagus.

Figures

FIGURE 5. Tychobythinus villasmundi sp. nov. Paratype female, habitus, dorsal view (Ph. A. Marletta).

FIGURES 6–9. Tychobythinus villasmundi sp. nov. 6. Head in dorsal view, schematic drawning. 7. Holotype male, head, dorsal view (Ph. A. Marletta). 8. Holotype male, head, lateral view (Ph. A. Marletta). 9. Holotype male, head, ventral view (Ph. A. Marletta). Scale: 0.1 mm.

FIGURES 10–13. Tychobythinus villasmundi sp. nov. 10. Holotype male, left antenna. 11. Paratype female, rigth maxillary palpus. 12. Holotype male, aedeagus, dorsal view. 13. Paratype female, telisternite, dorsal view. Scale: 0.1 mm.