Melichergithus gravidus ( Melichar, 1906 ) Constant & Pham, 2024

Constant, Jérôme & Pham, Hong Thai, 2024, Sixteen issid planthopper species in one day in Dong Son-Ky Thuong Nature Reserve in North Vietnam: Eight new species, one new genus and additional new records (Hemiptera: Fulgoromorpha: Issidae), European Journal of Taxonomy 919 (1), pp. 1-87 : 28-37

Melichergithus gravidus ( Melichar, 1906) gen. et comb. nov.

Figs 1 , 13–19

Gergithus gravidus Melichar, 1906: 59 (keyed), 61 (described). Types in NHMW.

Gergithus gravidus – Lallemand 1942: 70 (listed). — Fennah 1978: 267 (recorded from Cuc Phong, Ninh Binh Province). — Che et al. 2007: 612 (recorded from China, Guangxi, described), figs 1–4 (head, thorax, wings). — Meng & Wang 2012: 3 (keyed). — Gnezdilov & Constant 2012: 573 (listed from Vietnam). — Chen et al. 2014: 52 (described, recorded from China, Guangxi), fig. 2-15 (specimen, details, terminalia). — Gnezdilov et al. 2014: 82 (listed from Vietnam). — Gnezdilov 2017b (transferred back from Gnezdilovius Meng, Webb & Wang, 2017 , compared to representatives of Maculergithus Constant & Pham, 2016 ).

Gnezdilovius gravidus – Meng et al. 2017: 18 (transferred to Gnezdilovius ). — Zhang et al. 2020: 204 (keyed in Chinese, transferred back from Gergithus ), 219 (described), 547 (keyed in English), fig. 72 (head, thorax, wings, female terminalia), pl. XVI, a–c (habitus).

Diagnosis

Melichergithus gravidus ( Melichar, 1906) gen. et comb. nov. is the only species in the genus Melichergithus gen. nov.

The characters of the male terminalia ( Figs 17–18 ) must be used for species recognition, for example the elongate, laminate lateroventral processes of the periandrium, the long sinuate shaft-shaped lateral processes of the periandrium, the long lateral spinose processes of the ventral lobe of the periandrium curved cephalad or the more or less round anal tube (in dorsal view).

Material examined

Syntypes

VIETNAM • 2 ♀♀ (examined from photographs – Fig. 13 ); [Lang Son Province], Mount Mau Son ; [21°50′17″ N, 106°54′49″ E]; Apr.–May [1900]; H. Fruhstorfer leg.; “Tonkin, Montes Mauson; April, Mai 2 -3000’, H. Fruhstorfer ”, “ gravidus n. sp. det. Melichar ”; NHMW.

Additional material

VIETNAM • 1 ♂ (dissected, Figs 14 , 17 ), 1 ♀; Quang Ninh Province, Dong Son-Ky Thuong Nature Reserve ; 21°08′29″ N, 107°04′53″ E; 27 Aug. 2022; 550 m a.s.l.; secondary forest; GTI Project; J. Constant, J. Bresseel and L. Semeraro leg.; I.G.: 34.518; RBINS • 1 ♂ (dissected); Tonkin , Hoa Binh; [20°48′48″ N, 105°20′18″ E]; Jul. 1939; A. de Cooman leg.; R.I.Sc.N.B. I.G.18.385; Gergithus gravidus Mel. det. V. Lallemand 1940; RBINS • 1 ♀; Tonkin , Hoa Binh; R.I.Sc.N.B. I.G.23.285; H. Synave det. 195. Gergithus gravidus Mel. ; RBINS • 1 ♂ (dissected), 3 ♀♀; Tonkin , region of Hoa Binh; 1928; A. de Cooman leg.; MNHN ( EH24639 , 24640 , 24643 , 24644 ) • 4 ♂♂ (dissected), 6 ♀♀; Hoa Binh Province, Ngoc Son-Ngo Luong Nature Reserve ; 20°26′16″ N, 105°20′15″ E; 25–30 Jul. 2016; GTI Project; J. Constant and J. Bresseel leg.; I.G.: 33.282; RBINS • 2 ♀♀; Ninh Binh Province, Cuc Phuong National Park ; 20°19′00″ N, 105°36′30″ E; 19–23 Jul. 2011; J. Constant and J. Bresseel leg.; I.G.: 31.933; RBINS • 1 ♂ (dissected); Hoa Binh Province, Mai Chau ; [20°40′47″ N, 105°00′36″ E]; 30 Jun. 2001; 900 m a.s.l.; H.T. Ta leg.; VNMN • 1 ♀; Hanoi Province, Ba Vi National Park ; 21°4′4″ N, 105°21′30″ E; 25–29 Jul. 2015; day collecting; J. Constant and J. Bresseel leg.; I.G.: 33.092; RBINS • 1 ♀; Phu Tho Province, Xuan Son National Park ; 12–18 Aug. 2022; 21°8′23″ N, 104°56′29″ E; J. Constant, J. Bresseel and L. Semeraro leg.; I.G.: 34.518; RBINS • 1 ♀; same locality as for preceding; 12 Jun. 2004; H.T. Pham leg.; VNMN • 1 ♀; Thai Nguyen Province, Vo Nhai, Than Xa ; [21°50′23″ N, 105°54′14″ E]; 16 Oct. 2004; H.T. Pham leg.; VNMN • 5 ♀♀; Vinh Phuc Province, Tam Dao National Park ; 21°31′ N, 105°33″ E; 25–30 Jul. 2011; day time; J. Constant and J. Bresseel leg.; I.G.: 31.933; RBINS • 1 ♂ (dissected), 2 ♀♀; Thanh Hoa Province, Xuan Lien Nature Reserve, near Hón Can station ; 19°51′42″ N, 105°12′50″ E; 10–11 Jul. 2023; J. Constant, J. Bresseel and L. Semeraro leg.; I.G.: 34.661; RBINS • 1 ♂ (dissected); Ha Tinh Province, Vu Quang National Park, near Co station ; 18°17′21″ N, 105°22′30″ E; 16–18 Jul. 2023; J. Constant, J. Bresseel and L. Semeraro leg. I.G.: 34.661; RBINS .

Supplementary description

MEASUREMENTS AND RATIOS. LT: ♂ (n = 1): 5.4 mm, ♀ (n = 1): 5.9 mm; LT/BB = 1.23; LTg/BTg = 1.5; LW/BW = 2.0; BV/LV = 2.3; LF/BF = 0.85.

COLOUR. Variable with 2 main morphs: (1) black and bright yellow, with yellow transverse bands on frons, yellow marking on disc of tegmen and several, alternate black and yellow concentric lines along costal margin of tegmina ( Figs 13 , 15–16 ); (2) black, with one yellow transverse band along frontoclypeal suture ( Fig. 14 ).

LEGS. With pro- and mesofemora ventrally with 3 contrasting black transverse markings and black line along anterior margin; pro- and mesotibiae with black line along outer margin; metafemora black with yellow markings; metatibiae black with more or less developed yellowish white portion in distal ⅓ sometimes extending basad.

MALE TERMINALIA. Pygofer (Py – Figs 17A–C , 18A–D ) short, curved, about 3 times as high as long at mid-height in lateral view, with posterior margin somewhat angularly rounded in middle in lateral view; suboval in caudal view. Gonostyli (G – Figs 17A–B , 18A–C ) convex, with ventral margin nearly straight and posterior margin rounded in lateral view; elongate in ventral view; capitulum (ca) rather short, with a wide neck with basal hump on posterior margin, with apical tooth directed mesad and lateral laminate process at mid-height. Anal tube (An – Figs 17A–C , 18A–D ) dorsoventrally flattened, ventrally slightly depressed medially, 1.2 times as wide as long in midline in dorsal view and with anal opening in basal half. Aedeagus ( Figs 17D–I , 18E–J ) asymmetrical, strongly upcurved in lateral view. Ventral lobe of periandrium (vl) laminate with 2 longitudinal rows of minute teeth hooked cephalad, and with elongate, thin, lateroventral processes (lvp) sinuately curved dorsocephalad, left one before midlength of aedeagus, right one after midlength; lateral margins minutely denticulate; sides roundly projecting dorsad; median portion developed into a lobe obliquely weakly sinuate apically. Lateral lobes of periandrium (ll) laminate, moderately curved posteroventrad, reaching about half length of aedeagus and covering base of lateral elongate processes of periandrium; latter shaft-like, directed caudad in basal half then strongly curved dorsocephalad. Connective (co) well developed, corpus connective long, regularly and rather weakly curved in lateral view, tectiductus (te) well developed, reaching about half length of corpus connective, conical with wide anterior foramen.

Biology

Melichergithus gravidus gen. et comb. nov. was collected in August on lower vegetation and bushes, in moist evergreen tropical forest at about 550 m in altitude in Dong Son-Ky Thuong Nature Reserve ( Fig. 1B ). In other places it was also collected in moist evergreen tropical forest, at altitudes from about 150 m in Cuc Phuong National Park to over 1000 m in Tam Dao National Park in the months from April to August, and in October. The specimens were often observed waving their forelegs ( Fig. 19B ), the conspicuous markings of which might be used for communication.

Distribution

North Vietnam and northern Central Vietnam: provinces of Hanoi, Ha Tinh, Hoa Binh, Lang Son, Ninh Binh, Phu Tho, Quang Ninh, Thai Nguyen, Thanh Hoa and Vinh Phuc ( Fig. 19A ).

Note

The specimens from Guangxi recorded and illustrated in Che et al. (2007), Chen et al. (2014) and Zhang et al. (2020), might represent an undescribed species based on the male terminalia illustration in Chen et al. (2014), so the presence of M. gravidus gen. et comb. nov. in Guangxi (hence in China) is regarded as doubtful.

Figures

Fig. 1. Dong Son-Ky Thuong Nature Reserve. A. Topographic map. B. Sampled habitat.

Fig. 13. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., syntypes, ♀♀ (NHMW – photographs by H. Brückner). A–D. Syntype 1. A. Habitus, dorsal view. B. Habitus, frontal view. C. Habitus, lateral view. D. Labels. E–F. Syntype 2. E. Habitus, dorsal view. F. Labels.

Fig. 14. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., dissected ♂, black morph from Dong Son-Ky Thuong Nature Reserve (RBINS). A. Habitus, dorsal view. B. Habitus, ventral view. C. Habitus, lateral view. D. Habitus, perpendicular view of frons. E. Right hind wing.

Fig. 15. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., dissected ♂, typical morph from Ngoc Son-Ngo Luong Nature Reserve (RBINS). A. Habitus, dorsal view. B. Habitus, ventral view. C. Habitus, lateral view. D. Habitus, perpendicular view of frons. E. Anterolateral view. F. Right hind wing.

Fig. 16. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., dissected ♂, typical morph from Mai Chau (VNMN). A. Habitus, dorsal view. B. Habitus, ventral view. C. Habitus, lateral view. D. Habitus, perpendicular view of frons. E. Anterolateral view. F. Right hind wing.

Fig. 17. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., ♂, black morph from Dong Son- Ky Thuong Nature Reserve (RBINS), terminalia. A–C. Pygofer, anal tube and gonostyli. A. Lateral view. B. Caudal view. C. Dorsal view. D–I. Aedeagus and connective. D. Left lateral view. E. Right lateral view. F. Caudal view. G. Ventral view. H. Dorsal view. I. Anterodorsal view. Abbreviations: see Material and methods.

Fig. 18. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov., ♂, typical morph from Ngoc Son- Ngo Luong Nature Reserve (RBINS), terminalia.A–D. Pygofer, anal tube and gonostyli.A. Lateral view. B. Laterocaudal view. C. Dorsocaudal view. D. Dorsal view. E–J. Aedeagus and connective. E. Dorsal view. F. Left lateral view. G. Right lateral view. H. Left lateroventral view. I. Right laterocaudal view. J. Left laterocaudal view. Abbreviations: see Material and methods.

Fig. 19. Melichergithus gravidus (Melichar, 1906) gen. et comb. nov. A. Distribution map. B. Live specimen on fern, Xuan Lien Nature Reserve, 11 Jul. 2023. C. Live specimen on fern, Cuc Phuong National Park, 20 Jul. 2011. D. Habitat in Cuc Phuong National Park, 20 Jul. 2011.