Careocallus Cherman, 2024

Cherman, Mariana A., Basílio, Daniel S., Clarkson, Bruno, Agostinis, André O., Smith, Andrew B. T., Vaz-De-Mello, Fernando Z. & Almeida, Lúcia M., 2024, New and revised taxa of Neotropical Diplotaxini (Coleoptera: Melolonthidae): do they change the existing relationships? Revisiting systematics with morphological and molecular data, Zoological Journal of the Linnean Society 201 (1), pp. 98-135 : 119-128

Genus Careocallus Cherman , gen. nov. ( Figs 8–11 )

ZooBank: urn:lsid:zoobank.org:act:01587959-22AB-49A9-835D-FF7DAD5DF8A2

Type species: Careocallus tehuelche .

Diagnosis

Careocallus is distinguished from all other Diplotaxini genera by the following combination of features: clypeus trapezoidal, coplanar with frons (2:0); anterior margin subemarginate (6:0) ( Figs 8B , 10B ); apex of mandible perpendicular to the axis, equal in length or slightly shorter than the labrum in frontal view (156:0) ( Fig. 12A, D ); antenna with 10 antennomeres (40:0); constriction between pro- and pterothorax (58:1); elytra coarsely punctate, punctures elongate (61:1); three elytral ridges; first gap of ridges on its distal half as wide as the innermost ridge (66:1); sutural ridge extending from the base of scutellum (65:0), not uniform in width along its length (64:1), and angulate on apex (157:1) ( Fig. 14F ); procoxa without scales on infracarinal surface (69:1); protarsomeres I– III combined as long as or longer than head (79:0); metatibia with apical spurs even in shape (97:0); protarsomere I as long as protarsomere II (80:0); in males all tarsi slender ( Fig. 8C ), protarsomeres I– III inconspicuously wider than the others (133:0); in females elytra strongly convex ( Fig. 9B ), hindwings brachypterous ( Fig. 11C ); subapical callus of elytron inconspicuous ( Fig. 10F ) or even absent in males ( Fig. 8E ), completely absent in females ( Fig. 9C ).

Description

Length: 6.5–14.7 mm; width: 3.5–7.2 mm. Body elongate in males, oval in females; body and elytra plum-coloured to brownish-red. Head: frons swollen; frons and clypeus coplanar; frontoclypeal division weak, outer margin of maxillae straight (14:0), galea with five teeth at the apex; distal palpomere oblong, apex more-or-less acuminate; sensorial surface forming a fovea deep or shallow, varying from not reaching the midline of the palpomere ( Careocallus densicollis Cherman and Smith , sp. nov.) to extending past the midline or reaching the apex ( C. tehuelche ) ( Fig. 8B ); apex of mandible bifid, perpendicular to the mandible axis ( Fig. 12D ), and in frontal view equal in length or slightly shorter than the labrum ( Fig. 12A ); labium quadrate; ligula slightly concave anteriorly; length of ligula shorter than the excavation; labial palpomere I longer and narrower than palpomere II; labrum convex on upper margin and longer than clypeus in frontal view ( Cherman et al. 2017, Fig. 13A ); antenna with 10 antennomeres, club lighter in colour and slightly longer than the funicle. Prothorax: pronotum wider medially, forming a lateral convexity; pronotal posterior corners in obtuse angle or subangulate, sometimes weakly carinate ( Fig. 8B ); hypomeron setose, long bristles throughout and few scales on inner margin. Pterothorax: scutellum ogival variable in width; punctate; metaventrite sparsely bristled. Elytra: glabrous, shiny, coarsely punctate; sutural ridge weak around the scutellum and more marked towards its apex, wider along the medial portion; elevated or not, in general unicolorous with the elytron; three elytral ridges more-or-less noticeable, separated by gaps, the first gap equal to or narrower than the second gap; the first gap distally as wide as the innermost ridge, subapical callus of elytron inconspicuous in males, completely absent in females. Legs: procoxae conical, with scattered bristles; protibial surface with two medial longitudinal carinae ( Figs 9A , 10B ); protibial inner margin concave and the outer one with three teeth, the apical tooth slightly oblique to the tibial axis (see Cherman et al. 2016: fig. 3E), the basal tooth is always the smallest; the two other protibial teeth equal in size, the three teeth equally spaced; basal articular lobe of metacoxae produced beyond the outer margin of trochanter; mesotibiae cylindrical or subquadrate, with two transverse carinae bearing long setae, mesotibial setae longer than the spines of the apical crown ( Cherman et al. 2017: figs 42–45), the apical carina on mesotibia complete, sometimes very strong forming a ring; pair of apical spurs on apex of mesotibia and metatibia; even or slightly uneven in length, the gap between spurs is equal to the base of one spur; protarsi long, slender; protarsomere I as long as protarsomere II or slightly shorter; all claws bifid and symmetrical, protarsal claws slightly longer than the others, up to one-half the length of the protarsomere V, inferior tooth reduced, raising from the midline of the superior tooth ( Fig. 9D, E ) or next to its base ( Fig. 10E ). Abdomen: propygidium slightly visible ( Fig. 10F ) or hidden by the elytra (especially in females) ( Fig. 9C ); sparsely bristled; pygidium flat, disc with bristles throughout or only at apex; varying from coarsely to weakly punctate; subquadrate or subtrapezoidal, pygidium twice the length of ventrite V; maximum width does not exceed the distance between the propygidial spiracles; apex of pygidium varies from quadrate, subquadrate to rounded.

Dimorphism

Female: Length: 9.1–12.3 mm; width: 4.7–7.1 mm. Size and body shape: strongly oval, shorter than males. Pterothorax: distance between mesocoxae and metacoxae very short, equal in length to metacoxae or shorter. Elytra: strongly convex, punctures coarser, elytral ridges wider, subapical callus absent ( Fig. 9C ), hindwings brachypterous ( Fig. 11C ). Legs: protibia shorter and wider, teeth of outer margin wider; mesotibia sometimes noticeably enlarged towards apex; apical transverse carina on mesotibia and metatibia commonly complete and proeminent; metatibia wider and shorter; protarsomeres as wide as in the other legs. Abdomen: the pygidium may differ from the male in shape, being narrower and slightly longer.

Male: Length: 6.5–14.7 mm; width: 3.5–7.2 mm. Head: club of antenna longer. Pterothorax: distance between mesocoxae and metacoxae longer than the metacoxae. Elytra: slightly convex or flattened dorsally, subapical callus unnoticeable, hindwings normal in size ( Fig. 11A, B ). Legs: inner margin of metatibia carinate from the medial portion towards apex, depending on the species uniformly straight ( C. tehuelche ) ( Fig. 8D ) or expanded from subapical portion ( C. densicollis ) ( Fig. 10D ); apex barely setose along the inner surface; two transverse carinae present posteriorly; the basal carina sometimes very weak, the apical carina incomplete or complete (that is crossing the disc of metatibia), pair of apical spurs even or uneven in length; protarsomeres I and II slightly wider than the others, in C. densicollis also the protarsomere III. Abdomen: more concave than in females. Parameres: basal region ( BR) sulcate at its longitudinal midline ( Figs 8F , 10G ), lateral margin, on a plane below expanded ( Fig. 10G ) or not ( Fig. 8F ); parameral split on the basal third ( Fig. 10G ) or in the second third ( Fig. 8F ); inner margins of parameres straight or convergent at the apex; apex spatulate, with margins rounded or subangulate; in lateral view parameres straight, coplanar with BR or not, sloped from subapical region and flattened on apex ( Figs 8G , 10H ).

Remarks on hindwings

Radial sector of the hindwings is more sclerotized in C. densicollis ( Fig. 11A ), while it is reduced in females of C. tehuelche ( Fig. 12A, B ). The radial sector is the most important during the flight activity. Moreover, the fold mechanism that involve the RA1 + 2, the RP loop and the MP veins, which is also responsible for the flight ( Kukalová-Peck and Lawrence 1993, 2004), is also reduced in hindwings of C. tehuelche females. This reduction possibly indicates that females of C. tehuelche do not fly.

Etymology

From Latin ‘ careo ’ (be deprived of); ‘ callus ’, (hard skin). The name refers to the absence of the subapical callus from the elytra. Masculine in gender.

Composition: Careocallus tehuelche and Careocallus densicollis .

Distribution and habitats

Careocallus occurs in southern Argentina, from San Luis province (northernmost record 35°34ʹS 65°19ʹW) up to Chubut (42°46ʹS 64°59ʹW). Its distribution encompasses the southernmost part of Pampas and mainly the Patagonian region, from the eastern Andes with wet winters towards the Atlantic dry region.

Careocallus and the other genera

Among all genera of Neotropical Diplotaxini, Careocallus and Liogenys exclusively share the longitudinal inner margin of male metatibia produced [except the clade ( L. tarsalis + L. forcipata )] (143:0),andcoveredwithsetaeoninnersurface(144:0)(variable among Liogenys species). Among the Neotropical Diplotaxini, Careocallus could be morphologically mistaken with Liogenys or Pachrodema . Compared to Liogenys , Careocallus is similar in size, colour, and number of antennomeres (10, as in most Liogenys ). The anterior margin of clypeus is subemarginate in Careocallus , which is uncommon among Liogenys species, though present in L. niger , L. unicolor Evans , and L. rufocastanea Moser ( Cherman et al., 2019) . Careocallus differs from Liogenys mainly in the clypeus trapezoidal ( Fig. 8B ), without lateral impressions; frons and clypeus coplanar; ocular canthus narrow distally and gradually wider towards the proximal region, at the junction with clypeus (head in shape most similar to Pachrodema ); apex of mandible perpendicular to the axis and almost as long as the labrum (156:0) (in Liogenys and Homalochilus the apex of mandible is in oblique plane to the axis) ( Fig. 13E, F ); anterior margin of labium with emargination wider than in Liogenys ; labial palpomere I narrower and longer than palpomere II (in Liogenys palpomere I slightly wider and shorter than palpomere II); labrum longer than clypeus in frontal view (39:0) ( Fig. 13A ) (in Liogenys it is shorter; Fig. 13C ); pronotum narrower posteriorly than in Liogenys ; and mesotibial setae longer than the spines of the apical crown (as long as or shorter in Liogenys ) (see Cherman et al. 2016:: fig. 3).

In addition to most of the previous features, Careocallus resembles Pachrodema in the head in shape; frons swollen, not forming a concavity with clypeus; and frontoclypeal division present, though weakly marked. According to both implied weighting and equal weighting hypotheses ( Figs 1 , 2 ), Pachrodema and Careocallus are not sister-lineages due to the prothorax– pterothorax insertion, less constrained (58:1), inner margin of mesotibia straight, not concave (82:0), and the protibia with basal tooth more than one half shorter than the middle tooth (131:0) (see Cherman et al. 2016: Figs 2D , 3F to compare with Pachrodema ).

Careocallus differs from both Liogenys and Pachrodema mainly in the subapical callus of elytron not distinguishable in males, absent in females; sutural ridge of elytra weakly marked around scutellum (65:0) (in Homalochilus it is well marked around the scutellum and in the other Neotropical Diplotaxini raises from the apex of scutellum); first gap of ridges on elytra as wide as the innermost ridge (66:1); apex of sutural ridge angulate (157:1); distance of mesocoxae and metacoxae in females short, as long as the metacoxae; apical tooth of protibia oblique (74:0); all tarsi slender; length of protarsomeres I, II, and III combined as long as or longer than head (79:0); and males with protarsomeres I, II, and sometimes III slightly enlarged (excepting Homalochilus with all tarsi slender, the other Neotropical Diplotaxini also with tarsomere IV of the protarsi and mesotarsi enlarged).

IDENTIFICATION KEY TO CAREOCALLUS SPECIES

1. Body oval; pronotum with punctures homogeneously disposed ( Fig. 8B ), elytra convex, apex of sutural ridge in 90º ( Figs 8E , 9C ); protarsal claw with superior tooth four times the length of the inferior tooth ( Fig. 9D ); males with inner margin of metatibia straight ( Fig. 8D )....................................................................................................................................... Careocallus tehuelche

-. Body elongate; pronotum with punctures densely disposed anteriorly ( Fig. 10B ); elytra flat, apex of sutural ridge in obtuse angle ( Fig. 10F ); protalsal claw with superior more than six times the length of the inferior tooth ( Fig. 10E ); males with inner margin of metatibia expanded subbasally ( Fig. 10D )............................................................................... Careocallus densicollis

Figures

Figure 1. Equal weights analysis—strict consensus tree of 92 most-parsimonious trees obtained. The numbers displayed in each node correspond to the value of absolute Bremer and symmetric resampling supports (above and below, respectively).

Figure 2. Implied weighting analysis, one tree obtained with concavity constant value k = 8.750. The numbers displayed in each node correspond to the value of relative Bremer and symmetric resampling supports (above and below, respectively).

Figure 3. Phylogram of the 50% majority-rule consensus of trees for the 29-taxon dataset of Diplotaxini from Bayesian inference (BI) analysis based on the combined gene dataset (ITS2, COI). Values displayed above branches (orange) correspond to BI posterior probabilities (PP). Values displayed below branches (green) correspond to maximum likelihood (ML) ultrafast bootstrap (UB) proportions (>50%) in clades also present in the best ML tree.

Figure 8. Careocallus tehuelche. Male holotype habitus (A), head and pronotum (B), lateral (C), metatibia (D), posterior (E), and parameres in dorsal (F) and lateral (G) views.

Figure 9. Careocallus tehuelche. Female paratype habitus (A); lateral (B) and posterior (C) views; protarsal claw of female (D) and male (E).

Figure 10. Careocallus densicollis. Male holotype habitus (A); head and pronotum (B); lateral (C) and posterior (F) views; metatibia (D); protibial claw (E); parameres in dorsal (G) and lateral (H) views.

Figure 11. Hindwing in Careocallus. Careocallus densicollis male (A); Careocallus tehuelche male (B) and female (C).

Figure 12. Hindwing in Careocallus, detail of radial sector.Careocallus tehuelche male (A) and female (B).

Figure 13. Head in frontoventral view (A–C) and left mandible (D–G) of some Neotropical Diplotaxini. Careocallus tehuelche (A, D); Pachrodema sp. (B–G); Liogenys suturalis (Blanchard) (C, E); Homalochilus punctatostriatus (F).

Figure 14. Posterior margin of elytra, variation in apex of sutural ridge among Diplotaxini.Apex angulate (A, F); apex subangulate (E) or rounded (B–D). Diplotaxis tristis Kirby (A); Pachrodema castanea Blanchard (B); Homalochilus punctatostriatus (C); Pacuvia philippiana Gutiérrez (D); Liogenys suturalis (E); Careocallus tehuelche (F).