Onthophagus moroni Zunino and Halffter, 1988

Rivera-Gasperín, Sara Lariza, Escobar-Hernández, Fernando & Favila, Mario E., 2021, An Update on the Feeding Preferences of the Dung Beetle Onthophagus moroni Zunino and Halffter (Coleoptera: Scarabaeidae) from the Cuetzalan Caves, Puebla, Mexico, The Coleopterists Bulletin 75 (1), pp. 247-255 : 249-251

Onthophagus moroni Zunino and Halffter, 1988

Onthophagus moroni Zunino and Halffter 1988b: 19 ; Delgado 1999: 33; Zunino 2003: 68; Krajcik 2006: 119; Halffter and Deloya 2007: 139; Pulido-Herrera and Zunino 2007: 110; Zunino and Halffter 2007: 29; Slay et al. 2012: 92; Halffter et al. 2019: 8.

Redescription. Dorsal habitus ( Figs. 1A–C ):

Major male. Length 7.7–9.5 mm. Dorsal surface of

the body almost glabrous, with only short dark brown setae on the clypeus, antero-lateral parts of pronotum and elytral striae. Color shining black, elytra slightly sericeous with a violet-blue sheen. Head and pronotum with a slight greenish sheen. Head: Clypeus transverse, concave, subsinuate at the apex. Central and posterior parts of clypeus with wide, scattered and confluent punctures. Genae wide, with the basal third weakly concave. Genal sutures fine. Clypeal carina feebly indicated in the center, smooth and evanescent on the sides; in dorsal view with a trapezoid shape, open posteriorly. Central part of the head distinctly convex. Frontal carina quite evenly elevated, with double anterior convexity, lying at the level of the eyes and completely effaced laterally. Surface of frons with fine punctures. Pronotum: With fine basal margin that is clearly visible medially. Lateral margin sub-linear between the anterior and the intermediate angle. Pronotal prominence pronounced and apically rounded, intermediate tubercles obsolete, posterior tubercles located near the middle of the pronotum. Pronotal disc with well-defined and irregular main punctures, with non-uniform distribution, and with more abundant, irregular, smaller intervening punctures, non-uniformly distributed. Finer microsculpturing not evident. Elytra: Striae wide, well impressed, with irregular and fine punctures. Elytral interstriae weakly convex, surface sculpturing composed of irregularly aligned small granules, and very fine setae-bearing punctures. Microsculpture quite conspicuous, uniformly reticulate. Legs: Protibia very feebly arched, slightly dilated towards the apex. External margin of protibia denticulate; the basal tooth prolonged toward the base as a smooth lamina. Apical spur curved medially. Pygidium: Punctation quite dense and confluent, forming irregular transversely arranged wrinkles.

Female. Major female ( Figs. 1D, E ). Length 7.2–9.1 mm. Similar to the male except for the clypeus being sub-trapezoidal, sinuate apically; clypeal carina distinctly developed; frontal carina strongly developed, protruded laterally as two vertical tubercles, flattened antero-posteriorly; pronotum with the posterior tubercles located more anteriorly than those of the male.

Genitalia. Endophallite copulatrix (EC) ( Fig. 2A ): Left lobe (LL) rounded, slightly widened. Inner lobe of the free margin of the left lobe (InL) short and rounded. Medial keel (MK) (or keel of basal margin of endophallite copulatrix) elongate and slightly curved. Right lobe (RL) much longer than the left lobe. Median keel of right lobe absent. Internal keel of right lobe (InK) forming a rounded and sinuate tooth. Apex of the right lobe (RLA) oval. Additional inferior endophallite (AIE) ( Fig. 2B ): Subrectangular, relatively simple in appearance, without intricate folds, without development of the part closest to the margin where the lamellar spiny belt is inserted. Vagina ( Fig. 2C ): Expanded portion of the vagina (VEP) developed, membranous, with semicircular apical margin. Ventral sclerotization of the vagina (VVS) with the centralsuperior region sinuate and the lateral-inferior regions wide and outwardly directed. Tubular tract of the infundibulum (ITT) elongate, narrow, straight or nearly so. Median tract of the infundibulum (IMT) weakly developed. Caudal tract of the infundibulum (ICT) well developed. Spermatheca (Sp) ( Fig. 2D ): U-shaped, with the flex-de-sclerotized area elongated and narrowed, with a spermathecal gland inserted in the basal portion of the flex-de-sclerotized area. Spermathecal gland (SpG) well developed, smaller than spermatheca, with apex rounded and globose.

Type Locality. MEXICO: State of Puebla, Cuetzalan del Progreso: interior of the Tasalolpan cave .

Material Examined. 21♂♂, 12♀♀: Verbatim label data: MEXICO: Estado de Puebla, Cuetzalan, Cueva de Tasalolpan , 18-XI- 2018, 907 m ., Fer. Escobar-Hdez and Rivera-Gasper´ın. leg., 20°01 ′ 11.6 ′′ N 97°32 ′ 31.1 ′′ W. Cloud forest . Collected directly under droppings of rodents, 70 m . inside the cave ( Fig. 3A ). 6♂♂: Verbatim label data: MEXICO: Estado de Puebla, Cuetzalan, Gruta de Atepolihui, Cueva El Nido del Murciélago. 21- XII-2014, 1,030 m., Fer. Escobar-Hdez. leg., 20°00 ′ 41.42 ′′ N 97°32 ′ 32.44 ′′ W. Cloud forest . Collected directly in bat guano, 60 m . inside the cave. Paratype. 1♂ ( Fig. 3B ): Verbatim label data: MEXICO: Edo. de Puebla, Cuetzalan. 11-VIII- 1987, 1,520 m., G. Halffter, M. Zunino, C. Deloya, leg., Cueva de Tasalolpan. NOTE: This material, not yet registered in the collection of Dr. G. Halffter, was also examined ; 1♂, 1♀: MEXICO: Puebla, Cuetzalan, C. Tasalolpan, North entrance, “Zone D”. 21-XI-1986 on rock, L. Arellano leg. 1♂: MEXICO: Puebla, Cuetzalan, C. Tasalolpan , “Zone D”. 19-III-1987, in guano, J. Monterrubio leg. 1♀: MEXICO: Puebla, Cuetzalan, C. Tasalolpan, North entrance, “tunnel C”. 21-XI- 1992 in murcielaguina with soil, Montes de Oca leg.

Affinities. There are five species within the Onthophagus brevifrons species complex: O. cavernicollis , O. subtropicus , O. brevifrons , O. cuevensis and O. moroni ( Halffter et al. 2019) . Taking into account the study of genital morphology within the O. brevifrons species complex, Zunino and Halffter (1988b), consider O moroni as the sister species to O. cuevensis .

Feeding. Onthophagus moroni is closely associated with the latrines of Peters’ climbing rat, Tylomys nudicaudus (Peters, 1866) ( Rodentia : Cricetidae ). A large number of live adults were observed interacting above and below the rat latrine; apparently, they feed and nest on accumulated rodent droppings of the rats ( Ceballos 2014; Espinoza-Medinilla 2014; Morales and Vázquez 1987; Ram´ırez-Pulido et al. 2005) ( Figs. 3C–E ).

Figures

Fig. 1. Onthophagus moroni, male and female. A) Paratype male in dorsal view, B) Major male in anterolateral view, C) Minor male in anterolateral view, D) Female in dorsal view, E) Female in anterolateral view. Scale lines = 2 mm.

Fig. 2. Genitalia of Onthophagus moroni. A) Endophallite copulatrix, B) Additional inferior endophallite, C) Vagina, D) Spermatheca. AIE = additional inferior endophallite [this structure is referred to as “secondary lamella” by Zunino and Halffter (1988a), and “additional inferior sclerite” by Tarasov and Solodovnikov (2011)]; AM = articulation margin of endophallite copulatrix; EC = endophallite copulatrix [this structure is referred to as “principal lamella copulatrix” by Zunino and Halffter (1988a), and “lamella copulatrix” by Tarasov and Solodovnikov (2011)]; ICT = caudal tract of infundibulum; IMT = median tract of the infundibulum; InK = internal keel of right lobe; InL = inner lobe of the free margin of the left lobe; ITT = tubular tract of infundibulum; LL = left lobe [this structure is referred to as “superior left lobe of lamella copulatrix” by Tarasov and Solodovnikov (2011)]; LSBI = insertion of lamellar spiny belt; MK = medial keel (or keel of basal margin of endophallite copulatrix); RL = right lobe [this structure is referred to as “superior right lobe of lamella copulatrix” by Tarasov and Solodovnikov (2011)]; RLA = apex of right lobe; Sp = spermatheca; SpG = spermathecal gland; VEP = expanded portion of the vagina; VVS = ventral sclerotization of the vagina [this structure is referred to as “supporting sclerotization of the ventral part of the vagina” by Zunino and Halffter (1988a)]. Scale lines = 0.2 mm.

Fig. 3. A) Tasalolpan Cave, vertical profile showing the sampling site (modified from Sprouse 1979), B) Original dry preservation of Onthophagus moroni (paratype ♂) with its respective collection labels, C) Latrine with accumulated droppings of the Peters’ climbing rat, Tylomys nudicaudus, D) Detritus excavation, E) Individuals of O. moroni collected alive for the first time.