Agathomerus Lacordaire, 1845

Rodríguez-Mirón, Geovanni M. & López-Pérez, Sara, 2025, Redescription of the Neotropical genus Agathomerus (Coleoptera, Megalopodidae, Megalopodinae) and description of three new species from Mexico, ZooKeys 1227, pp. 143-158 : 143-158

publication ID	https://doi.org/10.3897/zookeys.1227.118934
publication LSID	lsid:zoobank.org:pub:702BFF6A-320B-419C-9964-A7539685B4A5
DOI	https://doi.org/10.5281/zenodo.14852829
persistent identifier	https://treatment.plazi.org/id/86286066-79A1-5D6C-B23F-CCC872ADEC98
treatment provided by	ZooKeys by Pensoft
scientific name	Agathomerus Lacordaire, 1845
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Genus Agathomerus Lacordaire, 1845 View in CoL

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Type species.

Agathomerus pulcher Lacordaire, 1845 , designated by Jacoby and Clavareau (1905).

Differential diagnosis.

Agathomerus differs from the other genera of Megalopodina by the spatulate shape of the spiculum gastrale; in the other genera it is forked or straight. Moreover, it is also distinguished by the following character states: mesoscutum apex emarginate, metatarsomeres I – III conical, metatarsomeres V longer than I – III and, usually, tergite II with three sclerotized portions. Whereas in Plesioagathomerus Monrós , Mastostethus and Homalopterus Perty the mesoscutum apex is rounded, metatarsomeres I – III are subcylindrical, metatarsomeres V are as long as I – III (except in Homalopterus where they are variable); in Plesioagathomerus and Homalopterus tergite II has two sclerotized portions and in Mastostethus tergite II is uniformly sclerotized.

In addition, Agathomerus differs from Mastostethus by the generally longer antennae and convex metaventrite. In Mastostethus the antennae are short and the metaventrite has a conical tubercle medially. It is distinguished from Homalopterus by the mandible with a lateral groove, last labial palpomeres fusiform, elytra without costae and long parameres. In Homalopterus the mandibles lack a lateral groove, the last labial palpomeres are bullet-shaped, the elytra is costate and the parameres are short. Agathomerus can be separated from Plesioagathomerus by the abdominal process projected between the metacoxae and by the long empodium. In Plesioagathomerus , the abdominal process is short and not projected between metacoxae, and the empodium is short.

Agathomerus differs from Pseudohomalopterus by the meso- and metaventral processes not joined in lateral view and the emarginate ventral apex of tarsomeres V. In Pseudohomalopterus , the meso- and metaventral processes are joined (as in Mastostethus ), and the ventral apex of tarsomeres V is emarginated and notched. Agathomerus is easily distinguished from Barticaria , Bothromegalopus Monrós , and Megalopus by the elongate and robust shape of the body and the subparallel external edges of the elytra. Whereas in Barticaria , the body is compact and subcylindrical; in Megalopus and Bothromegalopus , the elytra are raised behind the scutellum, the elytral suture is depressed, and the body narrows towards the apex (as in Pseudohomalopterus ).

Redescription.

Head. Constricted behind eyes; frontal surface along eye margins with ocellate punctures (Figs 1 F View Figure 1 , 2 I View Figure 2 ); frons variable, impunctate, glabrous. Interocular space usually transverse. Antennae variable in length and shape, usually reaching anterior edge of elytra (Fig. 1 A View Figure 1 ), with 11 antennomeres; scapes subconical; antennomeres II globose; III shorter than scape; V – X articulated laterally; XI usually ovoid; scape and II – IV with scattered setae; setae on V – XI short and dense. Eyes prominent and notched (Figs 1 F View Figure 1 , 2 I View Figure 2 ). Frontoclypeal groove conspicuous. Clypeus trapezoidal, punctate; surface of disc with erect pubescence, posterior region with a transverse, translucent band; labrum oblong, surface of disc sparsely pubescent, edge densely so. Mandibles triangular, not toothed; external side with groove, punctate, and with procumbent setae. Maxillary palps with 4 palpomeres, I subcylindrical, II clavate, III shorter than II and IV, IV subconical or bullet-shaped. Ligula bilobed. Labial palps with 3 palpomeres, I subcylindrical and very short, II clavate and longer than III, III fusiform and longer than I. Mentum bilobed. Gula trapezoidal, punctate.

Thorax. Pronotum trapezoidal (Fig. 1 H View Figure 1 ) or bell-shaped (Figs 3 G View Figure 3 , 4 F View Figure 4 , 5 F View Figure 5 ), wider than long; base wider than the anterior margin, with anterolateral projections; surface convex, with a groove (either continuous or discontinuous) on the anterior part; posterior part wider than anterior, usually with posterolateral punctures and wide posterolateral projections; posterior edge beaded, as wide as base of elytra. Procoxal cavities closed, procoxae contiguous, conical, protruding; mesocoxae ovate, below level of mesothorax; metacoxae subquadrate, metaxoxal space narrow. Mesoscutum (Fig. 1 G View Figure 1 ) with stridulatory files; apical region rounded or slightly emarginate. Scutellum subtriangular (Fig. 1 G View Figure 1 ). Elytra with external edges parallel (Fig. 1 A View Figure 1 ); surface slightly convex dorsally, punctate; humeri rounded, projecting anterolaterally. Mesanepisternum flat; meso- and metaventral processes not joined (Fig. 1 E View Figure 1 ). Metaepisternum with anterior part concave (Fig. 1 D View Figure 1 ). Leg pairs progressively longer posteriorly; pro- and mesofemur elongate; metafemur robust, elongate, male with or without ventral projections; metatrochanters truncate; tibiae with a row of denticles dorsally; apophysis long and rounded, apex with 2 spurs; pro- and mesotarsomeres I – III subconical (Fig. 1 L View Figure 1 ); metatarsomeres I – III subcylindrical (Fig. 1 M View Figure 1 ); on each leg tarsomeres IV reduced in size; tarsomeres V curved, dorsal edge mucronate, ventral edge emarginate, metatarsomere V longer than I – III combined; claws bifid; empodia long, with more than three setae (Fig. 1 K View Figure 1 ).

Abdomen. Last spiracle smaller than others (Fig. 1 J View Figure 1 ); pygidium subtriangular (Fig. 1 J View Figure 1 ), apically sparsely punctate and sparsely pubescent; sternite I with anterior edge beaded, abdominal process projected anteriorly between metacoxae; in females, last abdominal ventrite concave apically and, on internal surface, short projection into abdominal cavity.

Male genitalia. Aedeagus: dorsal portion of median lobe membranous; struts and lateral margins of median lobe sclerotized (Fig. 1 N View Figure 1 ); struts articulated with edge of aedeagus. Parameres long, fused (Fig. 1 O View Figure 1 ); tegmen ring lanceolate; roof short (Fig. 1 O View Figure 1 ).

Female genitalia. Spermatheca complex (Fig. 1 P View Figure 1 ); proximal part of spermathecal capsule boomerang-shaped, apex with velum; terminal portion of spermathecal capsule elongate. Sternite VIII bifurcate, apex and base trilobate. Spiculum gastrale straight.