Miridiba saigonensis ( Moser, 1912 )

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 : 58-60

Miridiba saigonensis ( Moser, 1912)

Figs 11 , 74–76

Holotrichia saigonensis Moser, 1912: 440 (type loc.: Ho Chi Minh City, Vietnam).

Holotrichia saigonensis – Frey 1970: 249 (in key).

Miridiba saigonensis – Keith 2006: 45 (combination). — Coca-Abia 2008: 682.

Diagnosis

External morphology of adult ( Fig. 74 ). Body size 22–25 mm. Dorsal surface glabrous. Clypeus with conspicuous punctures, concave, shorter than frons, arcuate laterally, anterior edge strongly emarginate at middle. Frons with punctures similar to those of clypeus; surface depressed laterally, depressions without punctures; frontal carina sharp. Anterior pronotal margin glabrous, strongly flanged, narrowed at middle and at lateral ends; posterior margin glabrous, moderately flanged except at middle; lateral margins glabrous, moderately elevated, sinuate and smooth at anterior half, posterior half moderately serrated; anterior angles sharp, not projected forward, posterior angles obtuse and rounded. Pronotal surface with strong and deep punctures, each one with a tiny bulge hardly visible. Prosternal process pentagonshaped. Scutellum without punctures at middle line. Elytral surface with punctures regularly distributed, each one with a tiny bulge hardly visible; apical callus well definite; epipleuron with sparse setae at basal part and membrane. Foretibia with moderate dorsal carina. Meso- and metatibia with transverse carina interrupted and complete respectively; inner margin of dorsal surface with few spines. Prepygidium with pubescence short but conspicuous; punctures irregularly distributed, posterior area with strong punctures bearing short setae, anterior area with punctures thinner than those on posterior one. Pygidium irregularly punctate; punctures thinner at anterior and posterior margins than at middle; surface without conspicuous pubescence, at most with short setae in each puncture, apical margin with long pubescence. Ventrites 1 and 2 with conspicuous short pubescence reclined and regularly distributed. Ventrites 3 and 4 with inconspicuous pubescence. Ventrite 5 moderately depressed at posterior half where shows punctures irregularly distributed and sparse long pubescence; anterior half with thin and dense punctures uniformly distributed and without conspicuous pubescence. Ventrite 6 moderately bulging anteriorly; strong and deep punctures; wrinkled appearance; conspicuous pubescence irregularly distributed. Male genitalia: dorsal branch ( Fig. 75 ) of parameres symmetrical, narrowing towards distal end, with a rounded tip curving downward; sutural scar completely fused. Ventral branches with elevations as waves at outer margin, apices expanded. Phallobase shorter than parameres. Endophallus ( Fig. 76 ) strongly armed with long spines at distal end; proximal end with smaller spines. Temones short, T-shaped, with distal ends of apophysis extended laterally surrounding endophallus partially, ( Fig. 76 ). Female genitalia as described for morphotype IV “ Bidentata ” ( Fig. 11 ).

Material examined

Lectotype (here designated) VIETNAM • ♂; “ Saigon ” [Ho Chi Minh City]; “ Donckier leg.”; “Coll. Brenske”; “ Holotrichia saigonensis Type ♀ Mos”; “ H. saigonensis Mos. ”; “Syntype Holotrichia saigonensis Moser 1912 labelled by MFNB 2017 ”; “♂”; “Lectotype Miridiba saigonensis ( Moser, 1912) Chuan-bu Gao & Coca- Abia det. 2017”; MFNB.

Paralectotype (here indicated) VIETNAM • ♂; “ Cochinchina ” [southern of current Vietnam ]; “ Holotrichia saigonensis Type ♂ Mos”; “ H. saigonensis Mos. ”; “SYNTYPE Holotrichia saigonensis Moser 1912 labelled by MFNB 2017 ”; “Paralectotype Miridiba saigonensis ( Moser, 1912) Chuan-bu Gao & Coca-Abia det. 2017. Miridiba behrensi Chuan-bu Gao & Coca-Abia det. 2017”; MFNB.

Other material

VIETNAM • 2 ♂♂, 6 ♀♀ (identified as M. behrensi herein); Cochinchina ; MFNB • 3 ♂♂ (identified as M. behrensi herein); Saigon; Donckier leg.; MFNB • 3 ♂♂ (identified as H. saigonensis herein); Saigon; Donckier leg; Gao and Coca-Abia det.; MFNB • 1 ♂ (identified as H. saigonensis herein); Cochinchina ; Gao and Coca-Abia det.; MFNB .

Remarks

Moser (1912) described Holotrichia saigonensis with a series of specimens from Cochinchina. Keith (2006) transferred this species without studying the types nor giving any justification. After studying seventeen specimens (MFNB) including two types, we agree with the transfer of H. saigonensis to Miridiba . Features of external morphology and genitalia prove that this species belongs to this genus. Moreover, the parameres with one dorsal and two ventral branches allowing us include this species in genital morphotype IV “ Bidentata ”. On the other hand, we have designated two syntypes as lectotype and paralectotype. After comparing these two types of M. saigonensis , we have noted that they differ from each other. The differences between them lie in the clypeus (more concave and deeply emarginate in lectotype than in paralectotype), frons (surface depressed laterally in lectotype and without depressions in paralectotype), and parameres (dorsal branch flat and wider in the lectotype, in the paralectotype narrower and with a dorsal depression). In addition to that, we have compared the paralectotype of M. saigonensis with types of M. behrensi and they are very similar to each other. Currently, M. behrensi is a synonym of M. bidentata ( Matsumoto 2016) , but it is not possible to compare the paralectotype of M. saigonensis with M. bidentata until types are studied. Then, we only can assert that the paralectotype of M. saigonensis is very similar to M. behrensi . Moreover, four other specimens, of seventeen studied, differ from the lectotype of H. saigonensis , and are also identified as M. behrensi in this study. Male and female genitalia of M. saigonensis shows features that characterize morphotype IV “ Bidentata ”. Hence, this species is included in this genital morphotype.

Distribution

Vietnam (Ho Chi Minh City).

Figures

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 73–76. 73. Miridiba behrensi Brenske, 1892, lectotype, ♂ (MFNB), habitus in dorsal view. 74– 76. M. saigonensis (Moser, 1912), lectotype, ♂ (MFNB). 74. Habitus in dorsal view. 75. Parameres in dorsal (A), ventral (B) and lateral (C) views. 76. Endophallus and temones in ventral view. Scale bars: 73–74 = 5.0 mm; 75–76 = 1.0 mm.