Xenogaster kymopoleia Pires-Silva, 2023

Pires-Silva, Carlos M., 2023, Two new species of the termitophilous rove beetle genus Xenogaster Wasmann from Brazil (Staphylinidae, Aleocharinae, Corotocini), Zootaxa 5239 (2), pp. 247-264 : 254-262

Xenogaster kymopoleia Pires-Silva , sp. nov.

( Figs. 47–91, 93, 95 , 99 )

Type material. HOLOTYPE, male. BRAZIL: “Itanhaém–S„o Paulo ; 23.II.1979; L. R. Fontes, S. A. Marques, col”. Dissected on slides ( MZUSP 21151 ). PARATYPES, 1 male, “Itanhaém–S„o Paulo; 24.XII.1978; L. R. Fontes” col. Dissected on slides ( MZUSP 21152 ); 1 female. BRAZIL: “Icapara—S„o Paulo; 15.VI.1990; L. R. Fontes, col”. Dissected on slides ( MZUSP 21362 ).

Male: ~3.1 mm ( Figs. 47–49 )

Female: ~2.8mm ( Figs. 50–52 )

Diagnosis. Body dark ferruginous, outer margins of elytra and pronotum dark reddish-brown. X. kymopoleia sp. nov. is characterized especially by the chaetotaxy of sternite VIII, which has a transversal row of four bristles, and by the antennomeres III–IV distinctively transverse and shorter than II and V.

Head ( Fig. 53 ). Rounded, slightly longer than wide. Sides behind eyes parallel in short area, narrowed apicad, forming rounded angles at base. Finely punctures on the dorsal area of the head, contrasting with the ventral, which has fine impressions, giving a rough appearance. Clypeus membranous, deflexed in front of antennal fossae, producing a transversal carina between posterior margins of antennal insertions. Gula elongated, triangular widest at base, elongate with about ⅔ of the total length of head. Gular sutures diverging gradually towards base. Antennae ( Fig. 54 ) partially cylindrical with 11 antennomeres; scape elongate, with about the same length of antennomeres II–V combined, slightly narrowed at base, almost straight internally. Antenommere I elongate, narrowed at base; III–V almost as long as wide; antennomere II elongated than antennomere III; VI–X transverse; V–VI subquadrate slightly decreasing apicad; VII–X subequal in length, wider than long, with anterior and posterior margins slightly arcuate. Antennomere XI ( Fig. 55 ) with one pair of coeloconic sensilla. Labrum membranous and slightly wider than long, membranous, with two long bristles on posterior margin. Mandibles ( Fig. 56 ). Symmetrical and widest at base; with an apical and subapical tooth; subapical tooth near apical and fronswardly directed. Sensitive pores at basal region of each mandible. Prostheca inconspicuous, occupying almost the entire mesal length (in fig. 56 indicated by red arrows). Maxilla ( Fig. 58 ) with cardo rounded laterally (not showed in the photo), stipes short, rectangular, slightly longer than wide; galea and lacinia narrow, arcuate and elongated, widest at base; galea and lacinia subequal in length, a thick bristle comb on the apex of internal edge of galea; Maxillary palpi 4-articulated, arcuate and longer than stipes; palpomere I reduced, almost indistinct, ring-like; II elongated, rounded at apical margin and strongly narrow at base, subcylindrical, with small bristles; III oval, globose, slightly shorter than previous, with a pair of long bristles at apex; IV with half of the length of previous segment, narrowed apicad. Labial palpi ( Fig. 57 ) 3-articulated; palpomere I elongated, cylindrical; II almost as long as wide, about ½ of the length of palpomere I; III elongated, narrow, longer than previous; Ligula prominent and bilobed, slightly emarginate; each lobe with surface somewhat scale-like; with a digitiform projection between lobes, bearing two apical spiniform sensilla. Prementum membranous, short. Mentum fused to submentum, with anterior margin straight, anterior and posterior angles divergent; one apical bristle on each edge of anterior margin and two small bristles sparsely distributed on medial region of anterior margin; sensitive pores sparsely distributed across the surface ( Figs. 59 , 98 ). Postmentum fused to gula.

Prothorax ( Figs. 62–65 , 83–86 ): Pronotum slightly wider than long, ferruginous with outer margins dark reddish-brown; posterior margin almost straight; lateral margins parallel, forming weak rounded angles; pronotum longitudinally and irregularly impressed, with a deep impression at the central region of pronotal disc; two longitudinal impressions each one near lateral margins forming a weak wave-like carina on each side; surface with irregular geometric shapes, bearing sparse and thick short bristles entirely, giving a crenulated and spiny appearance ( Fig. 83 ). Three bristles longitudinally distributed on each lateral margin. Meso- metathorax ( Fig. 67 ) weakly sclerotized, finely punctuated at posterior margin. Metendesternite ( Fig. 61 ) U-shaped internally, basal stalk bilobed at base; fucal arms wide and parallel, not reaching mesocoxal margins. Scutellum transverse and oblong. Metanotum ( Fig. 66 ) membranous, fused to metasternum; longer than metanotum. Wings reduced to stubs. Elytra ( Fig. 60 , 87–90 ) elongated, sides almost parallel; outer margin dark yellowish-brown, straight and densely punctuated, with a grainy appearance. Anterior margin declivous; inner margin almost straight, widely rounded from distal third to outer margin; apices convergent at suture; posterior margin forming a broad and rounded angle. Bearing a single long bristle on anterior margin. Elytra with irregular and geometrical shapes, each with a short stout bristle. Legs ( Figs. 68–70 ). Procoxae longer and subtrapezoidal, mesocoxae oval, and metacoxae triangular. Femora elongated and cylindrical; metafemur with inner margin narrow; tibia with almost the same length as the femur; covered with short bristles along the whole surface; protrochanter the shorter; meso- and metatrochanter about the same length; metatrochanter bearing a single long bristle. Tarsi ( Figs. 71–73 , 91, 93, 95 ); tarsal formula 5-5-5, with 4 th and 5 th tarsomeres almost fused, presenting a clear line of division between them–(In figs. 91, 93, 95, division line indicated by arrows). First tarsomere of pro- and mesotarsus almost of the same length as tarsomeres 4–5 combined; first tarsomere of metatarsus with almost the same length as metatarsomeres 2–4 combined. Last tarsomere each with two unciform claws and an angular dentiform projection between claws.

Abdomen physogastric with membranous areas among sclerites. Tergites and sternites separated by two pairs of paratergites in abdominal segments III–VI; bristles of tergites always on sclerites; inner paratergites sclerotized, subquadrate, outer paratergites narrow. Segment I membranous, reduced, fused to metanotum; segment II with a reduced tergite, shorther than tergite III, with anterior margin emarginate at middle; second sternite transverse, plate-shaped; tergites III–V rectangular; tergite III with posterior margin emarginate. Tergite VII ( Fig. 71 ) band-like and subtrapezoideal, with posterior margin slightly curved, anterior margin with a pair of glandular reservoirs, each widely separated; one row of 4 large bristles in the medial region, finely punctuated in the whole surface; posterior margin marginated by fringe of fine bristles. Tergite VIII subquadrate, wider than long, anterior margin slightly emarginate; lateral margins rounded; covered with fine short bristles on medial to posterior region. One transverse row of four bristles symmetrically distributed. Sternite VIII ( Fig. 75 ) subquadrate, wider than long, continuous laterally by sclerotized extension on females; and forming short angles in anterior margin of males; lateral margins slightly curved and posterior margin with rounded angles. One transversal row of four bristles on posterior region symmetrically distributed; small bristles and sensitive pores distributed across the whole surface; posterior margin marginated by fringe of fine bristles; sternite IX represented by a pair of hemisternites laterally attached to tergite IX in female ( Fig. 77 ), on males represented by three long extensions (apodemes) ( Fig. 80 ). Tergite IX subtriangular, covered with short bristles; two long bristles in a longitudinal row parallel to lateral margin. Tergite X ( Figs. 78, 80 ) band-like, fore angles rounded, covered with short bristles and with two transversal rows of bristles symmetrically distributed parallel to anterior margin. Aedeagus rounded, basal capsule broadly rounded, apical lobe narrowing apicad and bilobed ( Fig. 82 ). Lateral lobes with distal segment short, with short bristles on apex; medial segment broader and proximal segment elongate. Spermatheca ( Fig. 79 ) sclerotized. Stem elongated, with almost the same length as the capsule, which is cylindrical and elongated.

Type-locality. Brazil. S„o Paulo–Intanhém.

Remarks. Xenogaster kymopoleia differs from X. pseudonuda in the shape of mentum and pronotum, which has distinctive longitudinal impressions on each lateral margin. The shape of elytra, with the inner margins widely rounded from distal to outer margin and apices convergent, while X. pseudonuda have the anterior and posterior margins declivous and convergent. Finally, the species are also differentiated by the antennal segments: while X. kymopoleia has distinctive transverse segments VI–X, but X. pseudonuda has these segments subquadrate, to slightly wider than long.

Host. The holotype was collected together with Araujotermes caissara Fontes (MZSP 7716). The male paratype, with Nasutitermes sp. (MZSP 7739). The female paratype was collected with Nasutitermes jaraguae (Holmgren, 1910) collected on a thin, rotten, fallen branch (L. R. Fontes pers. comm.).

Data on the label of the termite cataloged as “MZSP 7716” (29.VII.–3.VIII.1978; L.R. Fontes & S.A. Marques col.) does not correspond to the information on the label of the holotype of X. kymopoleia ([presumably collected with termites MZSP 7716] MZUSP 21151— 23.II.1979; L.R. Fontes col.). Curiously, the corresponding data is found only on the labels of termites cataloged as “MZSP 7816” (Dr. M. M. Rocha (MZUSP), pers. comm). Probably a mistake occurred when the collector was writing the data (‘7716’ should have been written as ‘7816’). This is reinforced by the fact that the termite MZSP 7716 is identified as Araujotermes caissara , while MZSP 7816 as Nasutitermes sp. Due to the historical association of Xenogaster being found only with termites of the genus Nasutitermes , the association with A. caissara can be considered improbable.

Etymology. The specific epithet is an allusion to the wave-like impressions on the pronotum. The name is transcribed from the ancient Greek Κυμο- (Kymo-) + πόλεια (póleia), referring to the Greek goddess of violent sea and storms, daughter of the sea god Poseidon. Noun in apposition.

Figures

FIGURES 47–49. Xenogaster kymopoleia sp. nov., holotype male. Habitus. 47, lateral; 48, ventral; 49, dorsal. Scale bars = 0,72 mm.

FIGURES 50–52. Xenogaster kymopoleia sp. nov., paratype female. Habitus. 50, lateral; 51, ventral; 52, dorsal. Scale bars = 0,77 mm.

FIGURES 53–67. Xenogaster kymopoleia sp. nov. 53, head, ventral view; 54, antenna; 55, detail of coeloconic sensilla on antennomere XI; 56, mandibles, dorsal view; 57, labium, dorsal view; 58, maxilla; 59, prementum, ventral view; 60, elytra, dorsal view; 61, endosternite; 62, 63, 65, pronotum (dorsal, lateral); 64, prosternum; 66, scutellum, meso- and metanotum, and abdominal tergite I, dorsal view; 67, meso- and metaventrite, ventral view. Scale bars = 0,2 mm (54); 0,025 mm (57, 59); 0,04 mm (56); 0,05 mm (55, 58, 60, 63, 64, 65); 0,075 mm (61, 66, 67); 0,1 mm (53, 62).

FIGURES 68–82. Xenogaster kymopoleia sp. nov. 68, front leg; 69, middle leg; 70, hind leg; 71, front tarsus; 72, middle tarsus; 73, hind tarsus; 74, tergite VII; 75, sternite VIII (female); 76, tergite VIII (male); 77, tergite IX and sternite IX (female); 78, tergite X–IX (female); 79, spermatheca; 80, tergites IX–X and sternite IX (male); 81, lateral lobe; 82, aedeagus, dorsal view. Scale bars = 0,025 mm (79); 0,03 mm (72); 0,05 mm (71, 73, 74, 76, 78, 80, 81); 0,06 mm (69, 75); 0,075 mm (82, 77); 0,1 mm (68, 70).

FIGURES 83–86. Xenogaster kymopoleia sp. nov. 83, pronotum, dorsal view; 84, detail of bristles on anterior margin; 85, detail of lateral margin; 86, microsetae present across lateral margin. Abbreviations = pm: posterior margin; am = anterior margin. Scale bars = 1 µm (86); 2 µm (84); 10 µm (85); 30 µm (83).

FIGURES 87–90. Xenogaster kymopoleia sp. nov. 87, elytra (dorsal); 88, detail of apex of anterior margin; 89, detail of lateral margin; 90, small bristles distributed across the elytra. Scale bars = 1 µm (90); 3 µm (88); 10 µm (89); 20 µm (87).

FIGURES 91–96. Metathoracic legs. 91, 93, Xenogaster kypomoleia sp. nov.; 92, 94, X. pseudonuda sp. nov; 95, detail of last tarsomeres of X. kymopoleia and 96, X. pseudonuda. Division line of 4th and 5th tarsal segment indicated by arrow. Scale bars = 100 µm (91, 92); 20 µm (93, 94); 10 µm (95, 96).

FIGURES 98–99. 98, postmentum of Xenogaster pseudonuda sp. nov; 99, postmentum of Xenogaster kymopoleia, sp. nov. Abbreviations = ap: apical bristles.