Synapsis horaki Zídek & Pokorný, 2010

Bui, Van Bac & Bonkowski, Michael, 2018, Synapsis puluongensis sp. nov. and redescription of S. horaki (Coleoptera: Scarabaeidae), with a key to Vietnamese species, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 58 (2), pp. 407-418 : 413-416

Synapsis horaki Zídek & Pokorný, 2010

( Figs 2B,H,I , 4 A–G)

Synapsis horaki Zídek & Pokorný, 2010: 18 , figs 12–15 (original description).

Type locality. Vietnam, Vinh Phuc Province, Tam Dao, 900 m a.s.l.

Type material examined. HOLOTYPE: ♁, ‘ 6–10.v.1990 | Tam Dao | Vinh Phu Distr. | Vietnam | 900 m | Jan Horák leg.’ ( NMPC).

Additional material examined. VIETNAM: CAO BANG PROVINCE: Pia Oac Nature Reserve, primary forest, baited pitfall trap, 5.–20.v.2016, 22°34′3.6″N, 105°53′3.3″E, 1223 m, 1 ♁, 22°34′1.4″N, 105°53′3.3″E, 1220 m, 1 ♁, 22°34′3.1″N, 105°53′4.7″E, 1220 m, 1 ♁, 22°34′3.1″N 105°53′4.4″E, 1213 m, 1 ♀, Bùi Văn Bắc leg. (all in VNUF).

Diagnosis. Hypomeral cavities present; surface sparsely punctate, and not covered by macrosetae. Mesepisternal surface flat and rugose. Genae unexpanded. Frons unarmed. Pronotal anterolateral angles not protruding. Elytral striae weak and indistinctly punctate; elytral interval 2 swollen near base. Ventral surface of femora densely punctate.

Description. Body length 17.5–20.1 mm, body width 10.8–12.6 mm. Colour: Dorsal surface black and glabrous. Ventral surface black on head and shiny black on thorax, abdomen and femora. Reddish brown macrosetae upon legs and pronotal margins. Mouthparts, maxillary palpi and tarsi reddish brown. Antennae brown; antennomeres IV–VI darker than other antennomeres.

Head nearly semicircular, 4.4–5.3 mm long, and 7.5–8.5 mm wide. Clypeal surface extremely rugose; apex strongly and deeply emarginated, V-shaped; distance between apices of clypeal denticles (DDC) 1.4–1.6 mm; anterior margin flexed upwards with few reddish setae. Genae rectangular, quite distinctly separated from clypeus and frons by well-defined suture; surface strongly rugose and weakly punctate; margins of anterolateral angles with dense reddish macrosetae. Frons unarmed, only slightly swollen; surface weakly rugose and punctate. Antennae with 9 antennomeres; length of antennomere I approx. 1.4 mm, equal in length to antennomeres II–VI combined; antennal club approx. 1.4 mm.

Prothorax. Pronotum transverse, 4.8–5.1 mm long, and 9.3–10.6 mm wide, widest at anterior quarter; pronotal disc almost indistinctly punctate, except for small weakly punctured areas near base and sides (at 30× magnification); anterolateral angles sharp and not protruding. Two lateral carinae on each side of pronotum clearly distinct; margin of outer carina with dense reddish brown macrosetae; area between carinae smooth. Hypomeral cavities present; surface of cavities weakly and sparsely punctate, and without macrosetae. Meso-metaventrum plate almost smooth, with posterior median weak groove, and with distinct excavation near metacoxae; surface of sides and anterior part sparsely and weakly punctate.

Pterothorax. Elytra 10.4–12.1 mm long, 10.8–12.6 mm wide, with weak and indistinctly punctured striae. Elytral intervals convex, smooth and impunctate (at 30× magnification); interval 2 swollen near base. Mesepimeron and metepisternum flat, granulose and without macrosetae.

Legs. Ventral surface of profemora strongly, coarsely and quite equally punctate; macrosetae upon profemoral margin reddish brown and long, denser in anterior margin. Protibia (ProTiL 3.2–3.6 mm, ProTiW 2.3–2.9 mm) with three broad and flat lateral teeth; protibial spurs (ProTiSL 1.4–1.6 mm) sharp, strongly curved outwards near apex, and equal in length to protibial tarsus. Ventral surface of mesofemora strongly and unequally punctate; punctures becoming denser on third posteior part. Mesotibia (MesoTiL 3.5–4 mm, MesoTiW 1.3–1.5 mm) with two sharp spurs (1 stMesoTiSL 2.0– 2.4 mm, 2 ndMesoTiSL 1.1–1.3 mm). Ventral surface of metafemora strongly and unequally punctate; punctures denser on posterior half of metafemora. Metatibia (MetaTiL 4.7–5.1 mm, MetaTiW 1.3–1.5 mm) elongate and slightly curved. Metatarsus length 3.9–4.1 mm, with 5 metatarsomeres nearly similar in size.

Abdomen and pygidium. Abdominal ventrites opaque, indistinctly punctate, and narrower at midline. Pygidium 2.2–2.5 mm long, 4.0– 4.8 mm wide; surface slightly convex, scabrous, and with mixture of punctures and rugosities.

Aedeagus. Phallobase length 3.4–3.6 mm (in lateral view); basal suture with strong swelling at middle. Parameres length 2.0– 2.2 mm (in lateral view). Phallobase and parameres forming angle> 130 o.

Sexual dimorphism. Based on an examination of the four specimens (3 males and 1 female), we did not find significant differences in morphological characters between both sexes, except for the colour of compound eyes, being black in the female but yellow in males ( Figs 2H, I ). This finding is consistent with the observed sexes of S. puluongensis sp. nov., raising the possibility of using this character to distinguish both sexes of these two species.

Biology. All four specimens were collected in the Pia Oac Nature Reserve. The habitat is primary forests at an elevation of 1220 m a.s.l. characterized by a forest canopy cover ranging from 76 to 95%. The percentage of exposed soil was 0–5%, with 6–25% herbaceous plant layer and leaf litter cover of 96–100%. The forests has a complex structure with various storeys. Dominant trees range from 20 to 30 m tall and belong mainly to two dominant families: Fagaceae ( Castanopsis spp., Lithocarpus spp., Castanea spp.) and Lauraceae ( Litsea spp., Cinnamomum spp., Machilus spp.), the herbaceous and parasitic plants comprised Poaceae , Asteraceae , Orchidaceae and Loranthaceae .

Remarks. So far, Synapsis horaki was known only from the holotype specimen collected in the Tam Dao National Park, Vinh Phuc Province, northern Vietnam. The herein presented specimens constitute a new record for the Cao Bang Province and the first known female. Morphometric measurements are summarized in the Table 1 .

Figures

Fig. 2. Morphological details of Synapsis species.A–B – elytral surface:A – S. puluongensis sp. nov. with elytral striae strongly and densely punctate and interval 2 not swollen; B – S. horaki Zídek & Pokorný, 2010, with elytral striae impunctate and interval 2 swollen. C–D – metafemora: C – S. puluongensis sp. nov.; D – S. yama Gillet, 1911. E–F – setation of hypomeral cavities: E – S. puluongensis sp. nov.; F – S. birmanica Gillet, 1907. G – elytron of S. naxiorum Král & Rejsek, 2000 with weakly and sparsely punctate elytral striae and intervals weakly punctate. H–I – eye coloration in specimens of S. horaki Zídek & Pokorný, 2010: H – female; I – male.

Fig. 4. Synapsis horaki Zídek & Pokorný, 2010: A – dorsal habitus, male. B – ventral habitus, male. C – dorsal habitus, female. D – ventral habitus, female. E – aedeagus, dorsal view. F – internal sac of aedeagus. G – aedeagus, lateral view.