Mycetomoellerius mesopleuralis Santos, 2025

Mycetomoellerius mesopleuralis Santos , Chaul & Serrão sp.nov.

( Fig. 8 View FIGURE 8 )

Type material. Holotype worker: BRA: SP, Agudos, -20.758332, -42.864533, 1959-04-30, Kempf, W. (1 worker,

MZSPHYM0136545)[ MZUSP]. Paratypes workers:BRA:SP,Agudos, -20.758332, -42.864533, 1959-04-30, Kempf, W. (Twelve workers with the following codes: MZSPHYM0144990, MZSPHYM0144991, MZSPHYM0136543, MZSPHYM0136544, MZSPHYM0144992, MZSPHYM0144993, MZSPHYM0136545, MZSPHYM0144994, MZSPHYM0144995, MZSPHYM0136546, MZSPHYM0144996, and MZSPHYM0144997) [all in MZUSP, except MZSPHYM0144991 which is in DZUP]. GoogleMaps BRA: SP, Luiz Antônio, Estação Ecológica Jataí , -21.573941, -47.734546, Rogerio & Adriana col. (1 worker, MZSPHYM0136547) [ CELC]. GoogleMaps BRA: SP, Mogi Guaçu, Fazenda Caipirinha, -22.226970, -47.091813, Leal, I. R. (Two workers with the following codes: MZSPHYM0136548 and MZSPHYM0144998) [ MZUSP] GoogleMaps .

Worker measurements (holotype): HL 0.93, HW 1.06, HW1 1.09, MdL 0.72, SL 0.85, PeL 0.14, A3L 0.07, MsL 1.41, PH 0.25, PL 0.39, PpH 0.25, PpL 0.33, HfL 1.19, G1L 1.13.

Measurements in mm (10 paratypes measured): HL 0.89–1.01, HW 0.93–1.10, HW1 0.96–1.10, MdL 0.65– 0.73, SL 0.7–0.95, PeL 0.12–0.15, An3L 0.05–0.08, MsL 1.27–1.48, PH 0.20–0.26, PL 0.35–0.46, PPH 0.23–0.32, PPL 0.29–0.33, HFL 1.19–1.36, G1L 0.85–1.2.

Diagnosis. Body pilosity sparse, setae long and curved. Lateral pronotal spines well-developed; median pronotal spines well-developed, slightly basally fused. Mesonotum with two pairs of protuberances, anterior pair larger than posterior; mesopleural surface, apart from microtubercles, with one distinct digitiform protuberance anteroventrally directed. Frontal lobes subcircular, with crenulate margins; frontal carinae reach the vertexal margin. Postocular protuberance well-developed; preocular carinae extending to the vertexal margin. Vertexal corners angled, vertexal margin with distinct median emargination. Mandibles basally with oblique striations. First gastral tergite with linked tubercles, and a pair of lateral ridges.

Worker description. Medium-sized to large species for the genus standards; without strong polymorphism. Setation sparse on body, slightly longer and curved on dorsum of mesosoma and metasoma, shorter on head, suberect on legs and scape, appressed in flagelomeres. Integument matte, mildly farinose; uniformly brown, with head only slightly darker and appendages slightly lighter. Head. Eye mildly convex, slightly surpassing head lateral border. Mandibles shiny, except for oblique striations at base; masticatory margin with a total of ten teeth: apical tooth large followed by nine smaller, subequally-sized teeth. Anterior clypeal margin with a median notch about as wide as the maximum scape width. Frontal lobes subcircular, with crenulate margins; frontal carinae reaching vertexal margin. Frons shallowly concave. Vertexal carinae oblique, well-defined, extending towards the occipital region of head. Preocular carinae surpassing the vertexal margin as a projection in full-face view; postocular carina poorly developed, postocular protuberance well-developed. Vertexal corners angled, vertexal margin with distinct median emargination. In profile view, posterior section of ventral margin of head with a developed carina which has protuberances. Antennal scape slightly exceeding the vertexal margin, its maximum width just posterior to midlength, with many well-developed tubercles; totaling eleven antennomeres. Mesosoma. Pronotal medial pair of spines well-developed, with slightly fused bases; pronotum with a pair of well-developed anterolateral spines, sometimes with truncate tips. Mesonotum with two pairs of protuberances, an anterior larger pair, and a posterior reduced pair; mesopleural surface with several microtubercles and one prolonged digitiform protuberance directed anteroventrally in the inferior region of lower mesopleuron. Metanotal suture shallow and wide. Propodeum dorsum with well-developed tubercles, without well-defined lateral borders; pair of propodeal spines posterolaterally directed, slightly longer than the distance between their internal bases; propodeal spiracle projected from surrounding surface, posteriorly directed. Metasoma. In dorsal view, petiolar node subquadrate; postpetiole wider than long. Subpetiolar process merely a bump, and subpostpetiolar process tiny and digitiform. Petiolar node, postpetiole tergite and first gastral tergite covered by randomly distributed pilligerous tubercles; on first gastral tergite the tubercles are linked laterally and form a pair of longitudinal marginations, forming carinae, and some small tubercles forming interconnected carinae in dorsal region.

Queen and male. Unknown.

Geographic distribution. Brazil (São Paulo).

Comments. The new species is distinguishable from the others in the genus by the lower mesopleuron projection, which, in other species such as M. janildae , is limited to just a small edge of the cuticle, or located on the upper mesopleuron (as in M. holmgreni ). Mycetomoellerius mesopleuralis shows some resemblance to M. relictus and M. janildae for sharing with them the well-developed lateral pronotal spines. Short tubercles, a common feature of the genus, are much more developed and evident in M. mesopleuralis than in most other species, particularly on the antennal scapes and the first gastral tergite. The species is only known from three localities in the Atlantic forest domain.

Etymology. The specific epithet ‘ mesopleuralis ’ refers to the projection on the lower mesopleuron, with the

Latin suffix ‘-alis’ indicating relationship or belonging.