Ganganomala Ratcliffe, Jameson, and Zorn, 2018

Ratcliffe, Brett C., Jameson, Mary Liz & Zorn, Carsten, 2018, Ganganomala Saltini Ratcliffe, Jameson, and Zorn, a New Genus and Species of Anomalini (Coleoptera: Scarabaeidae: Rutelinae) from Bangladesh and Nepal, with a Revised Circumscription of the Tribe, The Coleopterists Bulletin 72 (4), pp. 717-735 : 722-731

Ganganomala Ratcliffe, Jameson, and Zorn , new genus

( Figs. 1–4 , 7–9, 11–12 , 14–21 , 23–27 , 31–32 , 36 ) Zoobank.org/ urn:lsid:zoobank.org:act:13EA55C1-33DD-427C-957C-53BC75E115CE

Description. Form: Elongate oval, robust, apices of elytra broadly rounded, pygidium exposed beyond elytra; dorsum convex, glabrous. Color dark reddish brown. Sexual dimorphism present on clypeus, protibia, and protarsomeres. Length 15.2– 16.2 mm; width 8.1–8.4 mm. Head ( Figs. 1–4 , 24–27 ): Frons flat or weakly concave, lacking tubercles, surface punctate, punctures minute or large. Frontoclypeal suture poorly indicated, obsolete medially, weakly arcuate, reaching each lateral margin near ocular canthus. Clypeus with surface flat or weakly concave, punctate, punctures minute or large; apex of male quadrate, strongly or moderately reflexed with anterolateral angle square; apex of female weakly rounded, moderately reflexed with anterolateral margin rounded; margins of male bowed inward, base slightly wider than apex; margins of female parallel, slightly narrower at apex than at base. Eye canthus planar, not cariniform. Interocular width equals 3.0–5.2 transverse eye diameters. Antenna with 9 antennomeres, club subequal in length to antennomeres 2–6. Labrum quadrate at middle, sides rounded, not visible or weakly visible in dorsal view. Mandible ( Fig. 15 ) rounded externally, dorsal surface flat, inner apex bifid (teeth short, acute), molar region with 12–16 lamellae, scissorial region brush-like (lacking teeth). Maxilla ( Fig. 14 ) with 6 acute teeth, apical tooth and 1 subapical tooth fused with base with 3 equally separated teeth; palpus 4-segmented, terminal segment subequal in length to segments 2–3 combined. Mentum ( Fig. 16 ) with surface flat or weakly convex, apex bisinuate; length subequal to 1.2 times greatest width; terminal segment of palpus subequal in length to segments 1–2 combined. Pronotum ( Figs. 1, 3–4 ): Widest at middle, width at base broad (subequal in width to elytral humeri), apical margin membranous, basal margin weakly protuberant posteriorly at middle. Disc evenly convex. Marginal bead present apically, laterally, and at base. Surface variably punctate, punctures with or without setae laterally. Scutellum: Parabolic, slightly wider than long, base declivous at elytral base. Surface variably punctate. Mesepimeron: Base not exposed beyond elytral base in dorsal view. Basal width broader than base of elytron. Elytra: Surface with longitudinal, punctate striae, punctures variable. Epipleuron from base to metacoxa rounded, beaded from base to near apex, with transparent membrane from metacoxa to apex. Apex subquadrately rounded. Propygidium: Concealed by elytra. Pygidium: Width about twice length at middle. Shape subtriangular in caudal view, weakly convex in lateral view. Surface punctate, some punctures setose; setae moderately long, tawny or reddish. Apex and lateral margins beaded. Venter: Prosternal process obsolete, not produced ventrally, not produced to trochanter, glabrous ( Fig. 2 ). Mesometasternal region lacking projection; mesocoxae nearly contiguous. Abdominal sternites lacking carinate ridge laterally (compare with Fig. 13 of A. dorsalis with carinate ridge). Apex of last abdominal sternite quadrate (male) or weakly rounded (female). Legs ( Figs. 7–9, 11–12 , 31–32 , 36 ): Profemur lacking rounded, dilated apex. Protibia with 3 external teeth, teeth subequally spaced ( Figs. 8–9 ); subapical spur on inner margin lacking (male, Fig. 7–8 ) or present (female, Fig. 9 ); spur subequal in length to protarsomere 2; base without protibial notch. Male protarsomere 5 robust (subequal in length to protarsomeres 1–4, width about 1/2 length) with well-developed internomedial protuberance ( Fig. 7 ); female protarsomere 5 normal (subequal in length to protarsomeres 2–4, width about 1/3 length) with poorly developed internomedial protuberance ( Fig. 9 ). Male inner protarsal claw entire (not split), robust (twice thickness of outer claw), and with inner, minute, apical tooth; female inner protarsal claw split, ventral ramus subequal to dorsal ramus. Unguitractor plate of protarsus produced beyond apex of protarsomere 5, laterally flattened, bisetose. Mesotibia widest at middle, weakly expanded at apex; external margin with 1 weak, oblique carina on basal 1/4 (with 5–7 spines) and 1 moderately developed, oblique carina at middle (with 6–8 spines); apex with 6–8 spines and 2 inner spurs, longer spur produced to near apex of mesotarsomere 2. Meso- and metatarsomeres 5 with moderately developed internomedial protuberance (male) or weakly developed protuberance (female). Male mesotarsus with claws simple, split in female with ventral ramus subequal in width to dorsal ramus. Unguitractor plate of meso- and metatarsi produced beyond apex of tarsomere 5, laterally flattened, bisetose. Metatrochanter with apex not or only weakly produced beyond posterior border of femur. Metatibia ( Fig. 11 ) widest at middle, weakly expanded at apex, external margin carinate with spines, spines on female more elongate than those on male; apex with 15–22 spines and 2 inner spurs, longer spur produced to near apex of metatarsomere 2. Metatarsus ( Fig. 12 ) with claws simple in male and female. Hind wing: Apex of AA 1+2 short, not united with CuA ( Fig. 18 ). AP 3+4 at base bulbous, with short, dense setae. ScA with reduced membrane and single row of poorly developed pegs. Region anterior to RA 3+4 lacking setae (except sparse setae near fold). Parameres: Parallel, simple, free (not fused), slightly overlapping at base ( Figs. 19–21 ). Spiculum gastrale: Weakly Y-shaped and with moderately developed sclerites ( Fig. 17 ). Gonocoxites: Poorly sclerotized, setose at apex.

Type Species. Ganganomala saltini Ratcliffe, Jameson, and Zorn by monotypy.

Higher-Level Classification. We place Ganganomala in the subtribe Anomalina based on the following characters: 1) pronotal base anterior to scutellum evenly rounded, never emarginate anteriad (emarginate anteriad in Popilliina ); 2) labrum more or less hidden beneath anterior margin of clypeus in dorsal view (projecting anteriorly beyond margin of clypeus in Isopliina ); 3) anterior coxae transverse (longitudinal in Isopliina ); 4) clypeus not strongly elongated, constricted, and reflexed (strongly elongated, constricted, and reflexed in Anisopliina ).

Generic Diagnosis. The following characters serve to diagnose the genus:

1. Protibia with three well-developed teeth on the external margin ( Figs. 8–9 ) (in most species of Anomalini , the external margin of the protibia has two teeth, although Anomala species may have 1–3 teeth, according to Arrow [1917]). Several exceptions to this character state illustrate problems with the current classification (or homoplasy of the character state) and include some species of Anomala , a few Asian Callistethus , Hoplopus Laporte , a few species of Mimela Kirby from Sulawesi and Africa, Micranomala Arrow , Microlontha Petrovitz , Tribopertha Reitter , Rhinyptia Burmeister (except Rhinyptia laeviceps Arrow ), and Pentanomala Ohaus.

2. Autapomorphic clypeal form in the male. The male clypeal apex is strongly reflexed, quadrate, with square anterolateral angles and the margins bowed inward (broader at apex than base) ( Figs. 24–25 ). The female clypeal apex is broadly rounded, moderately reflexed, with the margins subequal or lightly narrower at the apex than at base ( Figs. 26–27 ) (shared with many Anomalini ).

3. Male protarsus 5 greatly enlarged ( Figs. 7 , 36 ) (subequal in length to tarsomeres 1–4, widest width half length) and with well-developed internomedial protuberance (autapomorphic for the genus). This compares with male A. dorsalis (which is similar to Ganganomala ) in which the internomedial protuberance is less strongly developed ( Fig. 37 ).

4. All claws entire (simple or not split) in the male (shared with some species of Anomala , Mimela , and Cyriopertha Reitter and all species of Microlontha and Hoplopus ) with the protarsal inner claw thickened (twice thickness of outer claw), strongly curved, and with inner, minute, apical tooth ( Fig. 7 ); inner claws of pro- and mesotarsus split in female, metatarsal inner claw simple ( Fig. 12 ) (shared with many Anomalini ). Old World Anomalina in which all claws are entire (not split) include Hoplopus (both sexes), Anomala calcarata Arrow (both sexes), Anomala vittata Gebler (male), Anomala errans (Fabricius) (male), Anomala oxiana Semenov (male), Anomala semenovi (Medvedev) (male), A. pallens (Semenov and Medvedev) (male), Anomala euops Arrow (male), Anomala praenitens Arrow (male), Anomala vetula species-group (male), Anomala emortualis species-group (male), Mimela aurata (Fabricius) (both sexes), Mimela junii Duftschmid (both sexes), Mimela rugatipennis Graëlls (both sexes), Mimela lusitanica (Ohaus) (probably both sexes, although Branco (2005) noted a slightly cleft protarsal claw on the left side in the only known male), Mimela holosericea Matchatschke (both sexes), Cyriopertha (Pleopertha) arcuata Gebler (both sexes), Megapertha Reitter (males), and Microlontha (males; females unknown).

5. Protibial spur lacking in male ( Figs. 7–8 ). In Anomalina , this character state is shared with species of Cyriopertha , Microlontha , and some species of Singhala Blanchard and Proagopertha Reitter. The spur is minute but usually present in Hoplopus ; present and subapical in female Ganganomala ( Fig. 9 ) (shared with many Anomalini ).

6. Meso- and metatarsomeres 5 with moderately developed, internomedial protuberance (male) ( Fig. 12 ) or weakly developed protuberance (female) (weakly developed protuberance shared with many Anomalini ). In male A. dorsalis , the internomedial protuberance is less strongly developed.

7. Sexual dimorphism present ( Figs. 1–3 , 8–9 , 24–27 ) (shared with some Anomalini ).

Remarks. With approximately 1,125 species of Anomala in the Old World (P. Limbourg, personal communication, March 2018), very few regional Old World treatises for genera or species, and the lack of a useful dichotomous key to Old World genera (Machatschke’ s 1957 work is badly out of date), the starting point for an understanding of Anomalina biodiversity is a list of taxa. Löbl and Löbl (2016) listed 19 genera of Anomalina and 294 species and subspecies of Anomala that occur in the Asian portion of the Palearctic region (including Nepal but not including Bangladesh). For the Indian subcontinent, the only work that synthesized ruteline biodiversity was Arrow’ s (1917) Fauna of British India. Even at the time of publication, this work was incomplete because so much of the area had not been adequately explored for scarab beetles, and our knowledge of the fauna there was still rudimentary. More recently, scarab research in the Ganges River basin did not discover Ganganomala . A survey of Anomala from Buxa Tiger Reserve (West Bengal, India) (Sarkar et al. 2017), use of pheromone and light traps in Saharanpur for detection of white grubs associated with sugarcane (Sushil et al. 2017), and agricultural pest management reports (Sharma et al. 2002) did not, of course, reveal Ganganomala .

Ascertaining the classification status of this new taxon was at first perplexing. The taxon strongly resembles some Dynastinae based on male characters (the protarsal claws are unequal in size and entire, and the meso- and metatarsal claws are subequal in size), but it is indicative of Anomalini based on male and female characters (all tarsal claws are independently moveable, and the elytral margins possess a slender membrane) ( Machatschke 1957; Jameson et al. 2003). Employing the subtribal classification of Anomalini , we place the new taxon in the subtribe Anomalina (see “Classification of World Anomalini ” above). Genera in Anomalina share the following character states: the pro- and mesosternal processes are lacking; the base of the pronotum is as broad as the elytra; the mesepimera are hidden at the base of the elytra; and the elytra are longer than broad. Sufficient differences clearly separate the new genus from other genera of Anomalina (see “Diagnosis”): the absence of a protibial spur in the male; the unsplit claws in the male, with the protarsal inner claw strongly thickened and curved (autapomorphic in Anomalini ); the greatly enlarged male protarsus 5 with a welldeveloped internomedial protuberance; and the autapomorphic form of the male clypeus (apex strongly reflexed with square anterolateral angles, margins bowed inward).

We considered that Ganganomala might represent a currently named taxon within the Anomalina . All Anomala species have a protibial spur present in both sexes, tarsal claws of mostly unequal size on at least the front and middle legs (subequal claws on the middle legs present in several species of the otherwise very different former subgenus Psammoscapheus Motschulsky ), and at least one claw on the pro- and/or mesotarsus is split at its apex (exceptions are listed in “Generic Diagnosis”). Contrastingly, all the meso- and metatarsal claws on the male of Ganganomala are of equal size, and all claws are entire at their apices. We carefully considered similarities of the new taxon with A. dorsalis ( Figs. 5–6 , 10, 13 , 22 , 29–30 , 33–34 , 37 ), formerly in the subgenus Rhinoplia . This subgenus was proposed by Burmeister (1844) and included East Indian species with a strongly reflexed clypeal apex and “sharp” lateral corners as well as tridentate protibia. Anomala dorsalis is the type of the subgenus, which includes three names that are synonyms of A. dorsalis ( Anomala centralis Nonfried , Anomala imitatrix Nonfried , Anomala fraterna Burmeister ). Anomala dorsalis is similar in overall appearance, size, and reflexed clypeal apex in the male. Females of G. saltini and A. dorsalis share split pro- and mesotarsal claws ( Figs. 9–10 ) and a protibial spur (spur absent in the male of G. saltini ). However, the male of G. saltini has an entire, strongly thickened and curved protarsal claw ( Fig. 7 ), whereas it is split in A. dorsalis ( Fig. 37 ). Additional characters that separate these taxa are: the lateral margins of the abdominal sternites (simple in G. saltini but strongly carinate in both sexes of A. dorsalis ( Fig. 13 )); the lateral margins of the male clypeus (concave in G. saltini ( Fig. 25 ) but slightly convex in A. dorsalis ( Fig. 30 )); the dorsal coloration ( G. saltini is a bright, chestnut reddish brown ( Figs. 1–3 ) but usually testaceous to bright reddish brown and with or without black dorsal markings in A. dorsalis ( Figs. 5–6 )); and the body shape (compact and suboval in G. saltini ( Figs. 1–3 ) but elongate in A. dorsalis ( Figs. 5–6 )). The peculiar shape of the male protarsus in G. saltini ( Fig. 7 ), the form of the claws on all legs ( Fig. 12 ), the absence of a protibial spur in the male ( Fig. 7 ), the simple lateral margins of abdominal sternites (not carinate, compare with Fig. 13 ), and the form of the parameres (ventrally setose in G. saltini ( Figs. 20–21 ) versus glabrous ventrally in A. dorsalis ) demonstrate that this similarity is only superficial and not the result of close taxonomic affinity.

The overall resemblance of Ganganomala ( Figs. 1–3 ) and A. dorsalis ( Figs. 5–6 ) has resulted in taxonomic confusion. Chandra (1991) attempted to separate A. dorsalis from a similar anomaline species, both of which are distributed in Dehradun, India ( Chandra 1991). Chandra’ s diagnosis of these sympatric species was based on male genitalia, eye size, punctation of the head and pronotum, and color. Description of the form of the claws, protibial teeth, and clypeal form were lacking, and the diagnosis was not based on comparison of type specimens. Chandra proposed that one morphotype was conspecific with A. dorsalis and the other morphotype was conspecific with “ A. fraterna ” ( Chandra 1991) . Chandra proposed renewed species status for “ A. fraterna ”, which was then considered a synonym of A. dorsalis . However, examination (by CZ) of Burmeister’ s syntypes of A. fraterna revealed that the pro- and mesotarsi have split claws (also concurring with Burmeister’ s description of A. fraterna ). Based on the images in Chandra (1991), we suspect that Chandra’ s “ A. fraterna ” morphotype may be conspecific with Ganganomala .

Distribution. Ganganomala is known from Nepal and Bangladesh in the greater Ganges River drainage and the Indo-Gangetic Plain (floodplain of the Indus and Ganga-Brahmaputra River systems) ( Fig. 23 ). Chandra (1991) recorded putative Ganganomala (as “ A. fraterna ”) from Dehradun, India, also in the Indo-Gangetic Plain, but examination of Chandra’ s specimens would be needed to corroborate an Indian record.

Biology. Adults are attracted to lights at night, but otherwise we know nothing of this seemingly rare scarab beetle.

Etymology. Ganganomala is named for the Ganga River (Ganges River) that flows from the Himalayan Mountains, through the Gangetic Plains in India, through Bangladesh, and empties into the Bay of Bengal.

Figures

Figs. 1–6. Habitus of Ganganomala saltini in comparison with Anomala dorsalis. 1) G. saltini, male holotype, dorsal view; 2) G. saltini, male holotype, ventral view; 3) G. saltini, female allotype, dorsal view; 4) G. saltini, male paratype, lateral view; 5) A. dorsalis, male, dorsal view (syntype of Anomala fraterna, MLUH); 6) A. dorsalis, female, dorsal view.

Figs. 7–13. Comparative characters of Ganganomala saltini and Anomala dorsalis. 7) G. saltini, male, greatly enlarged protarsus 5, well-developed internomedial protuberance, simple claws, and protibial spur lacking; 8) G. saltini, male, external margin of protibia with three well-developed teeth; 9) G. saltini, female, protibial spur, claw split, and tibia with three external teeth; 10) A. dorsalis, female, protarsus similar to that of female G. saltini; 11) G. saltini, male, metatibial apex and metatarsomere 1; 12) G. saltini, male, moderately developed, internomedial protuberance on metatarsomere 5 and simple claws; 13) A. dorsalis, lateral ventrites with well-defined carina.

Figs. 14–22. Morphological characters for Ganganomala saltini and Anomala dorsalis. G. saltini: 14) Left maxilla, ventral view; 15) Left mandible, dorsal view; 16) Mentum, ventral view; 17) Spiculum gastrale and associated sclerites; 18) Hind wing, ventral view; 19) Parameres, dorsal view; 20) Parameres, lateral view; 21) Parameres, ventral view. 22) A. dorsalis (syntype of A. fraterna, MLUH), parameres, dorsal view.

Fig. 23. Distribution of Ganganomala saltini in relation to the Ganges River Basin and locations in Nepal and Bangladesh. Map courtesy of A. Smith.

Figs. 24–30. Head comparisons of male and female Ganganomala saltini and similar Anomalina, dorsal and dorso-oblique views. G. saltini: 24–25) Male, clypeus with apex strongly reflexed and quadrate, anterolateral angles square, margins bowed inward with apex broader than base; 26–27) Female, clypeus with apex broadly rounded and moderately reflexed, margins subequal or slightly narrower at apex than at base. 28) Singhala hindu, male, clypeal apex strongly reflexed, emarginate at middle; 29–30) A. dorsalis, male, clypeus with apex strongly reflexed and subquadrate, anterolateral angles acute, margins converging from base to apex.

Figs. 31–35. Protibiae of male and female of Ganganomala saltini, Anomala dorsalis, and Hoplopus marcens Peyerimhoff, dorsal views. 31) G. saltini, male, subapical spur lacking, three external teeth; 32) G. saltini, female, subapical spur present, three external teeth; 33) A. dorsalis (syntype of A. fraterna, MLUH), male, subapical spur present, three external teeth; 34) A. dorsalis, female, subapical spur present, three external teeth; 35) H. marcens, male, subapical spur lacking, two external teeth, third tooth nearly obsolete.

Figs. 36–46. Comparison of male Anomalina protarsomeres showing form of claws, protarsomere 5, apex of protarsomere 4, and relative lengths of protarsomeres 1–5 (see Table 2). Figs. 37–41 show taxa with split claws; Figs. 42–46 show taxa with entire (not split, simple) claws. 36) Ganganomala saltini; 37) Anomala dorsalis; 38) Anomala keithi Zorn; 39) Anomala n. sp.; 40) Anomala zornella Prokofiev; 41) Singhala tenella Blanchard; 42) Mimela rugatipennis; 43) Anomala vittata; 44) Megapertha massageta Kirsch; 45) Cyriopertha arcuata; 46) Hoplopus marcens.