Miridiba longiuscula (Moser, 1909) Gao & Bai & Fang & Li, 2021

Gao, Chuan-Bu, Bai, Ming, Fang, Hong & Li, Jun, 2021, Miridiba hani Gao, a new species from Hainan, China (Coleoptera: Scarabaeidae Melolonthinae: Rhizotrogini), with a new combination from Vietnam, Zootaxa 4996 (2), pp. 331-342 : 337-341

Miridiba longiuscula (Moser, 1909) new combination

( Figs. 36–43 )

Holotrichia longiuscula Moser, 1909: 471 (original description); Dalla Torre 1912: 204; Chang 1964: 149 (misidentification); Frey 1970: 294; Nomura 1977: 88.

Type locality. “ Annam ( Phuc-Son )” ( Fig. 43 ) .

Type material examined (2 syntypes). Syntype, ♂, badly damaged (antennae, head, prothorax, prolegs and in- ternal structures of abdomen are missing) ( MNHB): “ Annam / Phuc-Son / Nov. Dez. / H. Fruhstorfer [typeset] // H. longiuscula / Type ♂ Mos. [handwritten]”; syntype , ♂ ( MNHB) : “ Annam / Phuc-Son / Nov. Dez. / H. Fruhstorfer [typeset] // H. longiuscula / Type ♀ Mos. [handwritten; sex incorrectly identified]” .

Additional material examined (6 specimens). 1 ♂ ( MNHB) : “ Annam / Phuc-Son / Nov. Dez. / H. Fruhstorfer [typeset] // longiuscula, Mos [handwritten]”; 4 unsexed specimens, partially damaged (antennae, head, prolegs and prothorax are missing) ( MNHB), same data as previous specimen ; 1 ♂ ( MNHB) , “Tonking / Donckier ” .

Redescription. Male, habitus as in Figs. 36, 37 . Total body length13.7–15.0 mm (from apex of frons to apex of elytra), width across humeri 5.7–6.2 mm, body oval-elongate, strongly convex; dorsal surface glabrous.

Colour: Head, pronotum, scutellum, legs and basal elytral dark reddish brown; antennae, apical elytral and abdomen reddish brown.

Head: Antennae with 10 antennomeres; antennal club with 3 antennomeres. Dorsal surfaces of clypeus and frons dense punctate, punctures rough. Clypeus bilobate, wider and shorter than frons obviously; anterior margin strongly reflexed ( Fig. 38 ). Fronto-clypeal suture defined and wave-shaped ( Fig. 38 ). Frontal carina distinctly raised and curved backward. Interocular width equals 3.5 transverse eye diameters.

Thorax: Pronotum widest at posterior 2/5; anterior pronotum near anterior margin obviously constricted; dorsal surface sparsely punctate; distance between punctures more than 2 puncture diameters; punctures near anterior mar- gin denser than others; anterior margin smooth and flanged; lateral margin strongly expanded outwards, crenulate and reflexed developed near anterior angle; anterior corner obtuse; posterior corner obtuse and rounded; dorsal posterior pronotum with 2 setae ( Figs. 36, 38 ). Scutellum triangular, dorsal surface glabrous and sparsely punctate, 1.5 times wider than long; medial and posterior area without punctures; anterior margin bended backward. Dorsal surface of elytra glabrous; sutural costae developed; each elytron with 4 longitudinal flat stripes. Epipleura covered with few setae at base.

Legs: Metafemora ventrally with a row of robust setae near posterior margin. Protibia tridentate; dorsal surface with punctures sparsely; anterior tooth longest, basal tooth small; apical spur small. Meso- and metatibia with a complete transverse carina on outer surface, and with 2 small pubescent spines on dorsolateral margin, and without spine on dorsointernal margin. Two apical spurs differ in size; upper spur long, curved and blade-shaped. Apices of pro- and mesotarsomeres 1–4 with dense microsetae ventrally. Metatarsomere 1 0.8 times shorter than metatarsomere 2. Pro-, meso- and metatarsal claws, each with a strong tooth medially.

Abdomen: Sternites 1–5 densely punctate and setiferous, setae short; posterior sternite 5 moderately depressed; sternites 5 and 6 with long, soft setae.

Pygidium: 1.5 times wider than long; fan-shaped; dorsal surface glabrous and punctate; centre slightly up- heaved; apex obtuse.

Male genitalia. Phallobase: 1.4 times longer than parameres, arc-shaped in lateral view ( Fig. 39 ); anterior third reduced with a semi-circular membrane dorsally ( Fig. 40 ). Parameres: Basal paramere nearly saddle-shaped in dorsal view ( Fig. 41 ), with a thin longitudinal suture dorsally. Paramere with 2 dorsal and 2 ventral branches, dorsal branches larger and 2 times longer than ventral branches. Two dorsal branches fused at base with a wide groove medially in dorsal view, and separated at anterior 1/4. Ventral branches wide; each upper and lower anterior angle with a short branch; upper short branch prolonged upward, lower short branch curved inward and formed a circular gap medially ( Fig. 42 ). Spiculum gastrale Y-shaped.

Differential diagnosis. Holotrichia longiuscula shares the diagnostic combination of characters with the genus Miridiba representatives (frontal carina distinctly developed; antennal club with 3 antennomeres; apices of pro- and mesotarsomeres 1–4 with dense microsetae ventrally; parameres with branches). Thus, we transfer it into Miridiba and propose Miridiba longiuscula , new combination.

Miridiba longiuscula is distinguished from all other Miridiba species by combining features: Antennae with 10 antennomeres. Dorsal surfaces of clypeus and frons with rough punctures. Clypeus bilobate; anterior margin strong- ly reflexed. Frontal carina developed. Pronotal surface sparsely punctate, area near anterior margin constricted obviously; dorsum with 2 setae; anterior flanged; lateral margin crenulate and reflexed near anterior angle. Scutellum triangular, glabrous and sparsely punctate. Elytra with discal costae weak but visible. Epipleura with few setae at base. Apical protibial spur small. Outer surface of meso- and metatibia with a complete transverse carina. Dorsolateral margin of meso- and metatibia with 2 small pubescent spines. Dorsointernal margin without spine. Sternite 1–5 densely punctate and setiferous. Parameres consist of 2 long dorsal and 2 short ventral branches. Proximal paramere nearly saddle-shaped; two dorsal branches fused at base and separated at anterior 1/4. Each upper and lower anterior angle of ventral branches with a short branch.

Miridiba longiuscula is separated from the similar species Miridiba hani new species and Miridiba scutata (Reitter, 1902) by the constricted area near the anterior margin ( Fig. 38 ; lacking in M. hani as in Fig. 1 and M. scu- tata as in Fig. 27 ), the two setae in the dorsal surface of posterior pronotum medially ( Fig. 36 ; lacking in M. hani as in Fig. 1 and M. scutata as in Fig. 27 ) and the bilateral symmetrical branches of parameres ( Figs. 41, 42 ; asymmetric in M. hani as in Figs.22, 23 and M. scutata ).

Despite the similar external features, M. longiuscula cannot be a member of the morphotype Scutata because of the bilateral symmetrical branches of parameres. Herein we classified M. longiuscula as incertae sedis of the genus Mirdiba.

Chinese name. KDzṘffiĤffl

Distribution. Vietnam

Remarks. Although Moser (1909) identified a syntype mentioned above as a female, it was in fact a male. The habitus and the male genitalia are provided and illustrated ( Figs. 36–42 ).

Several specimens from Zhejiang and Jiangxi provinces of China were misidentified as H. longiuscula by Chang (1964). These specimens ( Figs. 42 , 43 in Chang 1964) differ from the syntype of M. longiuscula ( Figs. 39– 42 ) by the shape of the parameres. Nomura (1977) also suggested H. longiuscula could be a member of Miridiba , but no formal transfer was performed there for this species.

We studied all these specimens from Zhejiang and Jiangxi provinces. There is only one male specimen among them, and its male genitalia is missing. Based on the external morphological characters and the figures of male genitalia in Chang (1964), these specimens should belong to undescribed Miridiba species. Nevertheless, we are waiting for a formal description until more material will be available for study .

Figures

FIGURE 43. Distribution map of four Miridiba species.

FIGURES 36–42. Miridiba longiuscula (Moser, 1909), new combination (syntype). 36, habitus, dorsal view; 37, habitus, lat- eral view. 38, head and pronotum in dorsal view; 39, male genitalia in lateral view; 40, male genitalia in dorsal view; 41, para- meres in dorsal view; 42, parameres in ventral view. Abbreviations: db, dorsal branches; lsb, lower short branch; m, membrane; pb, phallobase; pm, parameres; s, setae; usb, upper short branch; vb, ventral branches. Scale bar: 5.0 mm for Figs. 36, 37; 1.0 mm for Figs. 38–42.

FIGURES 1–2. Holotype of Miridiba hani Gao, new species. 1, habitus, dorsal view; 2, habitus, lateral view. Abbreviations: es, epipleural setae. Scale bar: 5.0 mm.

FIGURES 26–35. Miridiba scutata (Reitter, 1902) (26–30) and Miridiba schoolmeesteri Keith, 2010 (31–35). 26, 31, antennae; 27, 32, head and pronotum; 28, 29, mentum; 29, 34, scutellum; 30a, 35a, metatibia in ventral view, 30b, 35b, metatibia in lateral view. Abbreviations: di, dorsointernal margin; dl, dorsolateral margin; n, notch. Scale bar: 0.5 mm for Figs. 26, 28, 31, 33; 1.0 mm for Figs. 27, 29, 30, 32, 34, 35.

FIGURES 17–25. Holotype (17–24) and allotype (25) of Miridiba hani Gao, new speceis. 17, sternites 5 and 6 in ventral view; 18, pygidium in lateral view; 19, pygidium in dorsal view; 20, male genitalia in lateral view; 21, male genitalia in ventral view; 22, parameres in dorsal view; 23, parameres in ventral view; 24, endophallus in dorsal view; 25a, female genitalia; 25b, genital chamber.Abbreviations: ac, accessory gland; bc, bursa copulatrix; db, dorsal branches; el, epithelium; ep, endophallus; gc, genital chamber; mo, median oviduct; p, peduncle; pb, phallobase; pm, parameres; s, spermatheca; sg, spermatheca gland; sp, spine; t, temones; vb, ventral branches; vt, vestigial tergites. Scale bar: 1.0 mm for Figs. 17–21, 24, 25; 0.5 mm for Figs. 22, 23.