Mesodiplatys falcifer Kamimura

Kamimura, Yoshitaka & Ferreira, Rodrigo L., 2018, Description of a second South American species in the Malagasy earwig genus Mesodiplatys from a cave habitat, with notes on the definition of Haplodiplatyidae (Insecta, Dermaptera), ZooKeys 790, pp. 87-100 : 89-94

Mesodiplatys falcifer Kamimura sp. n. Figs 1-6, 7-14

Material examined.

Holotype ♂, 'Lapa dos Peixes II | (UTM 612750, 8971635) | Carinhanha municipality,| Bahia, Brasil’, 'ISLA 46682', '15.x.2017 | Coleta Geral (general sampling), Ferreira R.L. leg.', 'HOLOTYPE (male) | Mesodiplatys falcifer | sp. nov. | Det. Y. Kamimura 2018'.

Diagnosis.

Mesodiplatys falcifer sp. n. is a small-sized species with a slender abdomen and simple forceps. This species differs all other species of Mesodiplatys with the combination of the following characters: the sickle-shaped sclerite in the penis lobe; notably short parameres lacking dentiform curvature near base on inner margin and its articulation with main body of genitalia perpendicular to its anterior-posterior axis; notably large eyes; and uniformly pale pronotum and darker tegmina.

Description.

Male (holotype, Figure 7). Measurements are shown in Table 1. Body color generally amber except for 3rd antennal segment and beyond, distal third of femur, basal half of tibia, tegmina (except for region around scutellum), fustis of wings, dorsal side of 7th abdominal segments and beyond, and lateral sides of 6th abdominal segment dark brown. Head and 1st and 2nd antennal segments black. Forceps reddish brown. Abdomen and forceps densely pubescent.

Head (Figs 1, 8) slightly longer than width, widest in eye region; frons tumid but weakly depressed at apex; occiput strongly and widely depressed; transverse and median sutures visible but not conspicuous; posterior margin strongly emarginated in middle with a pair of semi-oval tubercles lateral to median suture, of which outer-anterior angle protrudes dorsally as small papilla; post-ocular carina conspicuous as oblong swelling; lateral margins of post-ocular region bordered by strong bristles. Eyes conspicuously prominent, eye length 2.5 times the post-ocular length (EL/POL, measured along anterior-posterior axis as shown in Figure 1; Table 2). Antennae (Figs 2, 8) comprise 19 segments: segment I stout, expanded apically, length almost half of distance between antennal bases; segment II shorter than width; segment III twice as long as width; segment IV 1.5 times longer than width; segment V almost as long as III; remaining segments gradually lengthening. Pronotum (Figs 1, 8) slightly longer than broad; anterior margin almost straight; humeral angles strong; sides weakly narrow posteriorly; posterior margin broadly rounded; median sulcus visible but not distinct; prozona weakly raised. Tegmina (Figs 1, 8) well developed, approx. twice as wide as pronotum, 2.5 times as long as pronotum, broad triangular scutellum visible. Mesonotum with well-developed spiny ridge (a component of tegmina locking device sensu Haas 1995). Wings (Figure 1) well developed. Legs slender, notably long (Table 1); hind tarsi with segments I and II 3-3.5 times as long as III, claw with small arolium. Prosternum elongated, semi-rectangular, not constricted at middle; mesosternum hexagonal; metasternum semi-oval, narrowing posteriorly, posterior margin emarginated (Figure 3). Abdomen long, cylindrical, segments VIII and IX slightly expanded. Penul timate sternite (= sternite IX) elongated (Figs 4, 11), posterior margin almost truncate with rounded angles, regions at base of forceps weakly raised. Ultimate tergite (= tergite X) moderately inflated (Figs 5, 10), semi-oval, narrowing and sloping posteriorly. Forceps (cerci; Figs 5, 10, 11) slender, almost straight, densely pubescent especially on inner margins, tapering and weakly curving inward apically, inner margin with small tooth. Genitalia (Figs 6, 12-14), virga consists of bifurcated thin tubes, approx. three times as long as penis lobe, and 1.2 times as long as main part of genitalia (from base to distal end of paramere), spherical vesicle at base followed by short common duct; penis lobe also encloses sickle-shaped sclerite in characteristic swelling; parameres short, simple, triangular, distal part curving dorsally with many short spines near apex.

Female. Unknown.

Remarks.

Mesodiplatys falcifer sp. n. is apparently allied to M. venado Anisyutkin, 2014 recorded from Peru. However, in addition to the characteristic sickle-shaped sclerite in the penis lobe, the former species is distinguished from the latter by possession of triangular parameres, penultimate sternite with truncated posterior margin, and pale coloration of the pronotum. This new species is also differentiated from all Malagasy members of the genus with the combination of the following characters: sickle-shaped, distinct sclerite in penis lobe; notably short parameres lacking dentiform curvature near base on inner margin and its articulation with main body of genitalia perpendicular to its anterior-posterior axis; eyes notably longer than POL (Table 2); and uniformly pale pronotum with darker tegmina.

Previous authors have noted that the male of the Malagasy species M. insularis (Borelli, 1932) has conspicuously large eyes, twice the POL in length ( Hincks 1955; Brindle 1966, 1969). However, our reexamination of the holotype (male: Figure 15) at ZMH revealed that its eye length is only 1.6 times the POL (Figure 16), shorter than those of the two South American species (2.07-2.50) and some Malagasy species including M. nanus (Burr, 1914) and M. raharizoninai (Brindle, 1966) (Table 2). The genitalia of this species have not been illustrated. Although Borelli (1932) briefly described their characteristics including simple parameres and very long virga branches, the holotype does not include genitalia, which were likely removed from the main body. We were unable to locate any other slide-mounted materials derived from this specimen within the ZMH collection.

Thoracic traits, other than the shapes of the pronotum and tegmen, have not been described in detail for any Malagasy members of Mesodiplatys ( Burr 1904, 1911, 1914; Borelli 1932a, b; Hincks 1953, 1955, 1957; Brindle 1966, 1967, 1969; Steinmann 1974, 1986a, b). In the single paratype female of this species (Figs 17, 19), which has been preserved in ethanol, well-developed spiny ridges are visible through the tegmina (Figure 18). The morphologies of the thoracic sternites of this paratype are essentially similar to those of M. falcifer sp. n., including conspicuous emargination at the middle of the posterior margin of the metasternum (Figure 20). As another candidate member of Mesodiplatys , Diplatys viator Burr, 1904 has been reported from Madagascar. However, this species was described based only on a broken and discolored female specimen. Hincks (1955) treated Diplatys hova Burr, 1914, which was also described from a single male collected in Madagascar, as a junior synonym of D. viator . Although Hincks found a possible female specimen of this species in Burr’s collection, he failed to trace the male holotype, leaving the position of this species doubtful.

Key to known Mesodiplatys species (males only)

Etymology.

The species epithet refers to the sickle- or falx-shaped sclerite in the penis lobe, which is characteristic to this new species among the species of the genus Mesodiplatys known to date.

Distribution.

Bahia, Brazil.