Miridiba Reitter, 1902

Gao, Chuan-bu & Coca-Abia, María Milagro, 2021, Revision of the genus Miridiba Reitter, 1902 (Coleoptera, Scarabaeidae, Melolonthinae): genital morphotypes and new taxonomic data, European Journal of Taxonomy 749, pp. 1-94 : 5-16

Genus Miridiba Reitter, 1902

Miridiba Reitter, 1902: 170 .

Holotrochus Brenske, 1894a: 75 (non Erichson, 1840).

Holotrichia (Pledina) Reitter, 1902: 173 .

Shangaia Lucas, 1920: 592 .

Neodontocnema Arrow, 1948: 50 .

Hippotrichia Arrow, 1948: 51 .

Miridiba – Dalla Torre 1912: 248 (catalogue). — Lucas 1920: 420. — Smetana & Král 2006: 222 (catalogue). — Coca-Abia 2008: 673 (review). — Li et al. 2015: 522 (redescription; in key). — Bezděk 2016: 271 (catalogue). — Gao et al. 2018: 12 (catalogue); 2019: 461 (species list; in key).

Holotrochus – Dalla Torre 1912: 219 (catalogue). — Lucas 1920: 332 (as nom. nov. for Holotrochus Brenske ; catalogue). — Smetana & Král 2006: 222 (catalogue). — Coca-Abia 2008: 674 (type material). — Bezděk 2016: 271 (catalogue).

Holotrichia (Pledina) – Dalla Torre 1912: 200 (catalogue). — Chang 1964: 145, 148 (species list; in key). — Nomura 1977 (as subgenus of Miridiba ). — Smetana & Král 2006: 219 (catalogue).

Neodontocnema – Chang 1964: 145 (as synonym of Holotrichia ). — Nomura 1977: 88 (as synonym of Miridiba ). — Frey 1971: 223 (in key). — Smetana & Král 2006: 222 (catalogue). — Sabatinelli 1983: 123.

Hippotrichia – Chang 1964: 145 (as synonym of Holotrichia ). — Nomura 1977: 88 (as synonym of Miridiba ). — Smetana & Král 2006: 222. — Bezděk 2016: 271.

Shangaia – Itoh 1990: 5 (as synonym of Miridiba ). — Smetana & Král 2006: 222 (catalogue). — Bezděk 2016: 271.

Type species

Rhizotrogus trichophorus Fairmaire, 1891 , by original designation ( Reitter 1902).

Diagnosis

Species of Miridiba are distinguished from other melolonthines by the following combination of features. Head densely punctate. Antennal club in both sexes shorter than stem. Mentum with dense pubescence between its palpi. Labrum strongly depressed at middle of anterior part. Posterior frontal carina transverse and well developed. Vertex finely punctate with short decumbent pubescence. Pronotal anterior margin widely flanged, lateral margins smooth (not serrated) or serrated. Foretibia with a pubescent longitudinal carina. Apices of first four tarsomeres of fore- and mesotarsi with a tuft of setae ventrally. First ventrite under metacoxa, just its thickened posterior edge visible and not at the same level as next ventrite, with strong and short pubescence. Second ventrite densely punctate, with conspicuous and decumbent pubescence. Third and fourth ventrites with punctures and pubescence irregularly distributed, sparsely at middle and denser at sides. Fifth ventrite more or less depressed at posterior half, densely punctate and with conspicuous pubescence of different lengths. Sixth ventrite more or less concave, densely punctate and with conspicuous pubescence. Parameres with branches of variable shape. Genital chamber with reduced sternites or without them, median oviduct with wrinkled and/or hardened epithelium.

Redescription

External morphology of Miridiba is distinguished by the following combination of features.

COLORATION AND BODY SHAPE. Brown, body strong, oblong; length 11.0–26.0 mm.

HEAD. Antenna 9, or 10 segmented, antennal club with 3 lamellae shorter than stem (funiculus and scape). Mouthparts: mentum with dense pubescence between palpi, with a notch at middle of anterior edge; galea of maxilla with well-developed teeth; mandible with strong wrinkled molar lobe; edge of incisor lobe depressed in dorsal view; labrum strongly depressed at middle ( Coca-Abia 2008: figs 1–5). Clypeus densely punctate, shorter and wider than frons, with anterior edge emarginate to a greater or lesser extent or depressed at middle, arcuate or oblique laterally. Ocular canthus pubescent, flat, short (0.5 mm), start out below the clypeus. Frons densely punctate with frontal carina. Vertex with short conspicuous setae.

PRONOTUM. Widest at posterior half; pronotal surface more or less densely punctate; anterior margin widely flanged, narrowing towards lateral sides; posterior margin not flanged at least at middle; lateral margins smooth (not serrated) or serrated to a greater or lesser extent; anterior angles obtuse or acute, more or less projected; posterior angles obtuse. Prosternal process varying in shapes.

SCUTELLUM. With punctures more or less densely distributed, glabrous.

ELYTRA. Elytral surface without strong striations, at most with weak ones; sutural costa a little more developed than the other ones; punctures less defined than those of pronotum; epipleuron with or without marginal pubescence.

LEGS. Dorsal surface of foretibia with longitudinal carina developed to a greater or lesser extent and with a longitudinal row of pubescent punctures; three outer strong teeth spaced equally; insertion of inner spur between second and third outer tooth. Meso- and metatibia with transverse carina on outer surface complete or interrupted at middle; dorsal surface with or without spines. Metatibial plates with two articulated free spurs, proximal one behind tarsomere 1 and longer than distal one; the distal spur below tarsomere 1. Fore- and mesotarsi with a tuft of setae on apex underside of tarsomeres 1–4. Metafemora thick, surface with a row of coarse punctures near posterior margin with long and thick pubescence. Hind coxal plate rectangular shaped, with external free vertex forming a right angle. Tarsal claws sickleshaped with one tooth developed at medial.

ABDOMEN. Pygidium with surface punctate and pubescent or glabrous. Ventrite 1 almost completely under metacoxa, just its thickened posterior edge visible, not at the same level as next ventrite, with short pubescence more or less dense. Ventrite 2 densely punctate and with conspicuous, short and decumbent pubescence. Ventrites 3 and 4 with punctures and pubescence irregularly distributed, punctures denser and deeper at sides together with short and sparse pubescence. Ventrite 5 moderately depressed at posterior half, densely punctate and with conspicuous pubescence in different lengths. Ventrite 6 (anal plate) moderately concave, densely punctate with conspicuous pubescence, articulating by a complete suture. Ventrites 2–4 with the suture almost obliterated at middle.

MALE GENITALIA. Consisting of five parts: 1) Genital segment, derived from abdominal segment 9, resting on ventral wall of abdominal segments 7 and 8 ( Krell 1996), consisting of a Y-shaped sclerite (spiculum gastrale), a vestigial sternite and a vestigial tergite, which acting as an anchor for aedeagus to abdominal wall through a connective membrane. 2) Tegmen derived from abdominal segment 10 ( Krell 1996) consisting of parameres and phallobase (basal piece), both pieces articulated to each other. Parameres distinctively varying in shapes of dorsal and ventral branches among Miridiba species , apices of branches delimitating apical ostium (caudal); phallobase, a ventrally open structure partly obliterated by connective membrane, without sclerotized plates and with a gently dorsal strangulation as attachment point for connective membrane ( Krell 1996). 3) Endophallus (internal sac of aedeagus) lying within tegmen anchored through connective membrane and temones, evaginated during copulation through apical ostium. Epithelium covered with soft sensillae, occasionally, with areas termed raspulae, with dense sensillae and with spines of different sizes and shapes probably acting as a mechanism to anchor endophallus inside female genital chamber during copulation ( D’Hotman & Scholtz 1990b). 4) Temones, two dorsal elongate apophysis extending into basal piece; distal ends surrounding endophallus partially or completely. 5) Vesicula seminalis or caudal diverticulum, serving as a sperm reservoir.

FEMALE GENITALIA. Tubular type ( Lindroth & Palmén 1970), usually membranous, with parts of structures sclerotized, consisting of five parts: 1) Genital chamber at posterior extension of oviduct behind sternum 8, symmetrical bilaterally, opens through vaginal ostium or vulva ( Snodgrass 1935); dorsal wall with two folds (anal and gonopore folds), allowing its extension and retraction ( Fig. 1 ); anal fold at posterior position with two pairs of vestigial tergites, one pair at each side of rectum; gonopore fold at anterior position above opening of median oviduct (gonopore) and below of anal fold ( Fig. 1 ); ventral wall of gonopore fold with sensory structures (genital palps or styli) or plates located behind gonopore ( Fig. 1 ); ventral anterior end of genital chamber without or with one pair of vestigial sternites weakly developed, sometimes with sensory setae. 2) Accessory glands, on each side of anterior end of genital chamber with a dark area; probably produce pheromone for sexual attraction ( Zamotailov 1988). 3) Oviducts lead gonads from ovaries and opens ventrally to median oviduct, which is a wide chamber with wrinkled and/or hardened epithelium sclerotized to a greater or lesser extent, median oviduct is opened to genital chamber through gonopore ( Fig. 1 ) locating beneath genital chamber when the female genitalia rest. 4) Bursa copulatrix, diverticulum with function of storage and enzymatic digestion of spermatophore to deliver sperm ( Krell 1996), pedunculated, opens dorsally to median oviduct, with a pouch at proximal position with plicate epithelium and small setae of pressosensorial function ( Sanmartín & Martín-Piera 2003), some species with sclerotized structures in peduncle. 5) Spermatheca (receptaculum seminis or seminal receptacle) with function of sperm storage after releasing from bursa copulatrix, pedunculated with a pouch at proximal position, opens to median oviduct ventrally. Spermathecal gland, longer than spermatheca, opens at spermathecal tract just below pouch, its secretion leads sperm chemotactically through a concentration gradient from spermatophore to spermatheca ( Krell 1996). Both spermathecal and its gland have a distal tubular duct and a proximal caecum more or less globular.

Distribution

Species of Miridiba are documented in the eastern Palaearctic Region ( China, Japan, Korean Peninsula, Far East of Russia) and Oriental Region ( India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Thailand, Vietnam).

Genital morphotypes

Based on the examination of type series of twenty-eight species and eight synonymous taxa of Miridiba , nine genital morphotypes were established and described as follows.

Morphotype I “ Trichophora ”

Figs 2–4

Male genitalia

Parameres ( Fig. 2 ) consisting of two dorsal and two ventral thin branches separated in dorsal, ventral and lateral views; dorsal branches longer than ventral ones; branches start from a collar-shaped structure, termed collum at proximal part of parameres close to phallobase; collum short, with a suture dorsally and ventrally sclerotized to a greater or lesser extent. Endophallus ( Fig. 3 ) slim and graceful with spines becoming larger towards distal end and in some species arranged helicoidally around internal walls of the sac, some species with large spines or raspulae in distal end. Temones ( Fig. 3 ) laid at proximal half of endophallus; gently developed, seldom strongly developed, apophysis fused at proximal end.

Female genitalia ( Fig. 4 )

Anal fold with one tergite of each pair distinctly reduced; gonopore fold with a pair of sensory plates in oval-transverse shaped, plates with sensilla at posterior margin; vestigial sternites absent or weakly developed with a few sensillae. Median oviduct with wrinkled and/or hardened epithelium sclerotized to a greater or lesser extent. Bursa copulatrix with striated pouch. Spermatheca with short peduncle.

Morphotype II “ Gressitti ”

Figs 5–7

Male genitalia

Parameres ( Fig. 5 ) with a dorsal complex divided into three parts, upper part continuous and joined to collum by a membrane, intermediate and lower parts each with two branches. Two ventral branches simple and similar to those of morphotype I. Endophallus slim and raspulae conspicuous or gently at distal end, spines absent ( Fig. 6 ). Temones laid at proximal half of endophallus, thin and apophysis separated each other ( Fig. 6 ).

Female genitalia ( Fig. 7 )

Anal fold with all vestigial tergites similar in size; gonopore fold with a pair of elongate plates with sensillae at posterior edge; vestigial sternites weakly developed with a few sensillae. Median oviduct with wrinkled and hardened epithelium and two rectangular plates at distal dorsal wall. Pouch of bursa copulatrix striated with punctate sensillae. Spermatheca with short peduncle.

Morphotype III “ Leucophthalma ”

Fig. 8

Male genitalia ( Fig. 8 )

Parameres ( Coca-Abia 2008: fig. 17) consisting of dorsal and ventral branches separated in ventral and lateral views; dorsal branches only separated in distal end. Two ventral branches longer than dorsal ones, strong and curved downward. Collum absent. Endophallus with an area of soft setae, hair-like, at distal end, in some species spines arranged helicoidally around internal walls of sac. Temones laid at proximal half of endophallus, reduced; apophysis fused at proximal end.

Female genitalia

Anal fold with all vestigial tergites similar in size; gonopore fold with plates varying in shapes with sensillae at posterior margin; vestigial sternites weakly developed with or without sensillae. Median oviduct strongly sclerotized. Peduncle of bursa copulatrix very long. Spermathecal reduced, gland strongly developed with caecum longer than tubular duct.

Morphotype IV “ Bidentata ”

Figs 9–11

Male genitalia

Parameres ( Fig. 9 ) consisting of one dorsal and two ventral branches separated in lateral and ventral views. Presumably, dorsal branch resulted of two branches coalescence, showing a central sutural scar toward apical ostium varying in shapes and designs at distal end. Ventral branches bilaterally symmetrical, outer edge curved and elevated or straight; inner edge straight and converge at distal end. Collum absent. Endophallus ( Fig. 10 ) with a few spines and, in some species, raspulae with dense sensillae. Temones laid at proximal half of endophallus, apophysis joined at proximal end, some species with distal ends surrounding endophallus partially (T-shaped) ( Fig. 10 ).

Female genitalia ( Fig. 11 )

Anal fold with all vestigial tergites similar in size; gonopore fold with a pair of plates, without sensillae, in rectangular-elongate shape extending into median oviduct dorsal wall; vestigial sternites weakly developed with a few sensillae. Median oviduct with wrinkled and/or hardened epithelium sclerotized to a greater or lesser extent. Bursa copulatrix with long peduncle. Spermatheca with short peduncle, gland with marked pouch.

Morphotype V “ Sinensis ”

Figs 12–14

Male genitalia

Parameres ( Fig. 12 ) consisting of two dorsal and two ventral branches separated in dorsal and ventral views and fused laterally. Lateral scars, presumably, formed by the fusion of dorsal and ventral branches, or joined totally or partially by a lateral membranous area. Dorsal branches with symmetrical or asymmetrical design; collum undefined in lateral view, with a membranous area in dorsal view. Ventral branches bilaterally symmetrical, straight and convergent at distal end. Phallobase shorter than paramere. Endophallus ( Fig. 13 ) with a dense area of small spines (raspulae), stronger towards distal end, or raspulae absent, only acicular soft setae. Temones laid at proximal half of endophallus, slender, apophysis separated each other ( Fig. 13 ).

Female genitalia ( Fig. 14 )

Anal fold with all vestigial tergites similar in size; gonopore fold with a pair of short sensory elongate plates, with sensilla at posterior edge; vestigial sternites weakly developed without apparent sensillae. Median oviduct with wrinkled and hardened epithelium sclerotized to a greater or lesser extent. Bursa copulatrix with short peduncle, pouch arranged transversely. Spermatheca with short peduncle, gland very long.

Morphotype VI “ Borneensis ”

Figs 15–17

Male genitalia

Parameres ( Fig. 15 ) consisting of two dorsal and two ventral branches separated in dorsal and lateral views. Dorsal branches varying in shapes, reduced and shorter than ventral ones. Ventral branches joined by a dorsal membrane and fused ventrally forming up a tubular structure through which endophallus passes; apices of ventral branches separate. Collum absent. Parameres and phallobase joined by a wide dorsal membrane varying in shapes. Endophallus ( Fig. 16 ) almost empty, with few spines at middle of sac and inconspicuous sensillae. Temones laid at proximal half of endophallus, apophysis joined, distal ends surrounding endophallus completely ( Fig. 16 ).

Female genitalia ( Fig. 17 )

Anal fold with all vestigial tergites similar in size; gonopore fold with a pair of conspicuous plates varying in shapes without sensillae, extending into median oviduct dorsal wall; vestigial sternites absent; ventral wall of vulva with a gently sclerotized area with punctate sensillae. Median oviduct with wrinkled and/or hardened epithelium sclerotized to a greater or lesser extent. Bursa copulatrix with short peduncle. Spermatheca with long peduncle.

Morphotype VII “ Rugaticollis ”

Figs 18–19

Male genitalia

Parameres ( Fig. 18 ) consisting of one dorsal and two ventral branches. Presumably, dorsal branch resulted of two branches coalescence, showing a central sutural scar opened toward apical ostium. Dorsal branch thick and wide, gently narrowing toward apex in dorsal view; with a notch varying in shapes at distal end in lateral and ventral views. Collum undefined in lateral view and with a triangular-shaped area less sclerotized at proximal half. Ventral branches longer and thinner than dorsal ones, with apices gently

raised. Endophallus ( Fig. 19 ) with a sacculus bearing several short spines at distal half. Temones laid at distal end of endophallus, apophysis slender and separated ( Fig. 19 ).

Female genitalia

Unknown.

Morphotype VIII “ Scutata ”

Figs 20–22

Male genitalia

Parameres ( Fig. 20 ) consisting of one dorsal branch semi-tubular with proximal half obturated ventrally by a strong membrane; sutural scar absent; apex varying in shapes. Collum absent. Ventral branches thin, fused to dorsal one, emerging from edge of ventral obturating membrane toward distal end. Endophallus ( Fig. 21 ) with an area of conspicuous acicular setae (raspulae) and spines at distal end; a few spines isolated at middle of sac. Temones ( Fig. 21 ) laid at distal part of endophallus, slender; apophysis separated.

Female genitalia ( Fig. 22 )

Anal fold with all vestigial tergites similar in size; gonopore fold with a pair of sensory plates in ovaltransverse shaped, plates with sensilla along internal margin; vestigial sternites weakly developed with a few sensillae. Median oviduct slightly developed with membranous epithelium. Bursa copulatrix with part of peduncle striated. Spermatheca with long peduncle.

Morphotype IX “ Ciliatipennis ”

Fig. 23

Male genitalia

Parameres ( Fig. 23 ) consisting of one strong dorsal tubular complex divided into two parts, both parts with two branches at distal end; upper part with branches ( Fig. 23A ) varying in shapes and length; branches of lower part ( Fig. 23B ) shorter than those of dorsal part, convergent at distal end with varying shapes tips. In lateral view, branches of dorsal complex form a concavity ( Fig. 23C ) varying in shapes. Collum absent. Ventral branches reduced, fused laterally to dorsal tubular complex with a weak lateral scar. Endophallus with short spines and pointed sensilla at middle ( Gao et al. 2018: fig. 3j). Temones slender and apophysis separated ( Gao et al. 2018: fig. 3j).

Female genitalia

Not studied.

Species included in Morphotype I “ Trichophora ”

The group is composed of twenty-nine species, which are characterized by antenna 9-segmented, head and pronotal surface densely punctate (distance between punctures smaller than diameter of puncture) and male and female genitalia as specified above.

Figures

Fig. 1. Outline of the female genitalia of Miridiba Reitter, 1902 in lateral section. Abbreviations: see Material and methods throughout the figure captions.

Figs 2–4. Morphotype I “Trichophora”. 2–3. Male genitalia of M. trichophora (Fairmaire, 1891), paralectotype (MNHN). 2. Parameres in dorsal (A), ventral (B) and lateral (C) views. 3. Endophallus in lateral view. 4. Female genitalia of M. abdominalis (Hope, 1831), lectotype (BMNH), in dorsal (A) and ventral (B) views. Scale bars = 1.0 mm.

Figs 5–7. Morphotype II “Gressitti”. 5–6. Male genitalia of Miridiba herteli (Frey, 1971), paratype (NHMB). 5. Parameres in lateral view. 6. Endophallus and temones in dorsal view. 7. Female genitalia of M. gressitti (Frey, 1970), paratype (NHMB) in dorsal (A) and ventral (B) views. Scale bars = 1.0 mm.

Fig. 8. Morphotype III “Leucophthalma”. Male genitalia of M. leucophthalma (Wiedemann, 1819) (non-type, MFNB). Parameres in dorsal (A) and lateral (B) views. Scale bars = 1.0 mm.

Figs 9–11. Morphotype IV “Bidentata”. 9–10. Male genitalia of M. behrensi Brenske, 1892, lectotype (MFNB). 9. Parameres in dorsal (A), ventral (B) and lateral (C) views. 10. Endophallus and temones in ventral view. 11. Female genitalia of M. saigonensis (Moser, 1912),?syntype (MFNB) in dorsal (A) and ventral (B) views. Scale bars = 1.0 mm.

Figs 12–14. Morphotype V “Sinensis”. 12–13. Male genitalia of M. sinensis (Hope, 1842), lectotype (BMNH). 12. Parameres in dorsal (A), ventral (B) and lateral (C) views. 13. Endophallus and temones in ventral view. 14. Female genitalia of M. dalatensis Frey, 1970, holotype (NHMB) in lateral view. Scale bars = 1.0 mm.

Figs 15–17. Morphotype VI “Borneensis”. 15. Parameres of M. borneensis (Moser, 1918), lectotype (BMNH) in dorsal (A) and lateral (B) views. 16. Endophallus and temones of M. coxalis (Arrow, 1944), lectotype (BMNH) in dorsal view. 17. Female genitalia of M. coxalis, paralectotype (BMNH) in dorsal (A) and ventral (B) views. Scale bars = 1.0 mm.

Figs 18–19. Morphotype VII “Rugaticollis”. Male genitalia of M. rugaticollis (Moser, 1913), lectotype (MFNB). 18. Parameres in dorsal (A), ventral (B) and lateral (C) views. 19. Endophallus and temones in lateral view. Scale bars = 1.0 mm.

Figs 20–22. Morphotype VIII “Scutata”. 20. Male genitalia of M. scutata (Reitter, 1902), lectotype (MFNB), parameres in dorsal (A), ventral (B) and lateral (C) views. 21. Endophallus and temones of M. lassallei Keith, 2010, holotype (DKC) in lateral view. 22. Female genitalia of M. scutata, non-type (MFNB) in dorsal view. Scale bars = 1.0 mm.

Fig. 23. Morphotype IX “Ciliatipennis”. Male genitalia of M. ciliatipennis (Moser, 1903), lectotype (MFNB). Parameres in dorsal (A), ventral (B) and lateral (C) views. Scale bars = 1.0 mm.