Mahea sexualis Distant, 1909

Kment, Petr, 2005, Revision of Mahea Distant, 1909, with a review of the Acanthosomatidae (Insecta: Heteroptera) of Madagascar and Seychelles, Acta Entomologica Musei Nationalis Pragae (suppl.) 45, pp. 21-50 : 25-28

Mahea sexualis Distant, 1909

( Figs. 1-7, 31 , 40-41)

Mahea sexualis Distant, 1909: 32-33 , pl. 4 (description, figure of female).

Mahea sexualis: KUMAR (1974) : 44 (taxonomy, invalid lectotype designation).

Type locality. Seychelles, Mahé.

Type material. LECTOTYPE: ♁, ‘ Seychelles / Mahe / H P.T. 1906 [p] // Mahea / sexualis / Dist. [hw] // University Museum of / Zoology, CAMBRIDGE [p] // LECTOTYPUS / MAHEA / SEXUALIS / Distant, 1909 / des. P. KMENT 2005’ [p, red label] ( CUMZ), here designated. The lectotype is glued onto the tip of a pentagonal piece of card, with the pygophore removed and mounted on the same piece of card. The original piece of card is pinned under the new one. Antennomeres 3 and 4 of both antennae, right middle and hind legs, and all tarsi from left legs of the lectotype are missing. PARALECTOTYPES: 1 ♁ and 1 ♀, ‘ Seychelles / Mahe / H P.T. 1906 [p] // Distant Coll. / 1911-383 [p] // SYN- / TYPE [p, white circle with blue margin] // PARALECTOTYPUS / MAHEA / SEXUALIS / Distant, 1909 / des. P. KMENT 2005’ [p, red label] ( BMNH). The male paralectotype is pinned, its antennomeres 2-4 (left) and 3-4 (right), all left legs (except hind femur), right hind leg, apical part of scutellum and pygophore missing, and it has a large pinpoint in the scutellum. The female paralectotype is mounted on the tip of a pentagonal piece of card, with one separate leg glued on the same piece of card. Rest of legs and antennae are missing, right pronotal spine broken, and abdomen ruptured ventrally on the left side.

Redescription. Body slightly shining; basic colour ochraceous, with coarse dark punctures.

Male (lectotype) (Fig. 40). Length 7.5 mm, width of pronotum between humeral angles 4 mm. Head ( Fig. 1 ) pale ochraceous with coarse brown punctures forming more or less apparent rows (two rows on each mandibular plate, posteriorly coalescent, forming a figure resembling an 8 next to each eye; two rows on clypeus, partly coalescent medially, reaching to posterior margin of head, on frons surrounded by two rows forming an incomplete circle). Head shorter than wide (1: 1.35), its width about half that of pronotum between humeral angles (1: 2.08). Mandibular plates basally almost parallel, suddenly curved inwards apically, not meeting; apex of clypeus free ( Fig. 1 ). Eyes large, ochraceous; ocelli ochraceous, situated behind eyes, near anterior pronotal margin. Each antenniferous tubercle with black longitudinal spot laterally; antennae castaneous; antennomere 1 pale, basally ochraceous; antennomere 2 with erect pubescence, hairs slightly shorter than diameter of antennomere; length of antennomeres: 1 – 0.4 mm, 2 – 2.3 mm (ratio 1: 5.75). Head ventrally pale ochraceous, without punctures; apex of rostrum blackened, reaching middle of sternum 4.

Pronotum ochraceous with thick brown punctures; punctures on posterior half more dense than on anterior half; pronotal spines and narrow median line ochraceous; anterior margin concave; antero-lateral margins widening posteriad; humeral angles prominent, each abruptly produced into long, narrow spine directed laterad ( Figs. 2-3 ). Scutellum triangular, ochraceous, anterior part medially brownish, with brown punctures; anterior part arched, sloping posteriad; posterior part flat, apex blackened, triangular. Hemelytra ochraceous with brown punctures; suture between corium and membrane brown; membrane slightly brownish, translucent, slightly surpassing postero-lateral angles of sternum 7.

Thorax ventrally with coarse brown punctures, which are more sparse on metapleura; peritreme ochraceous. Metapleura swollen, its postero-lateral corners visible in dorsal view.

Legs ochraceous, apices of tibiae and tarsomeres 2 slightly blackened; hind femur and tibia with inner margin granulated, femur slightly swollen and curved inwards, tibia straight. Abdomen with only connexival spines visible from above; ventrally ochraceous, sterna 3-6 each with small black spot on each side near middle; median carina on sterna 3-6 well developed; postero-lateral angles of sterna 3-5 with small spines, sternum 6 with long posterolaterally directed spine on each side; sternum 7 parallel-sided, postero-lateral angles strongly produced posteriad; posterior margin of sternum 8 slightly incised medially ( Fig. 4 ).

Pygophore ( Figs. 6-7 ) brownish, dorso-ventrally flattened, postero-lateral angles each with tuft of long setae; parameres apically pointed, ventrally with setigerous punctures.

Female (paralectotype) ( Fig. 41 ). Length 8.2 mm, width of pronotum between humeral angles approximately 4.1 mm (right spine missing); punctures on body reddish; metapleura only slightly swollen, less prominent in dorsal view; abdomen ( Fig. 5 ) less narrowing posteriad, more flattened, unicolorous, without black round spots, median carina developed only on sterna 3-4; connexival spines as in Fig. 5 .

Variability. Male paralectotype differs from the lectotype in having the clypeus completely enclosed by mandibular plates; body length 7.4 mm, length of antennomere 2 equal to 2.4 mm. Differential diagnosis. Mahea sexualis differs from M. andriai , M. distanti sp. nov., and M. parvula by having each humeral angle abruptly produced into a long spine, not conical. From M. durrelli sp. nov. it differs by having the lateral pronotal margins regularly sinuated, the humeral spines not raised ( Figs. 2-3 ), the metapleura distinctly swollen, differently shaped connexival spines ( Figs. 4-5 ), and apex of each paramere pointed ( Figs. 6-7 ) (see also the key).

Bionomy. Unknown.

Distribution. Island of Mahé ( Seychelles). Known only from the type series.

Comments. DISTANT (1909) described M. sexualis based on both sexes, but he did not mention the number or the location of syntypes. The type locality was given unambigously as ‘Locality. Mahé’, but on the next line DISTANT (1909) wrote: ‘Dr. Schouteden has kindly sent me a male specimen of this species from Madagascar.’ The description was accompanied by a figure of a female from Mahé and a male from Madagascar.

KUMAR (1974) examined three specimens of M. sexualis deposited in the BMNH – one male and one female from Mahé, and one male from Madagascar. He wrote: ‘… the Madagascar male is a distinct species, quite different from Mahé specimens. … Distant’s description covers both species and his type label is affixed to the Madagascar specimen. In these circumstances, I have taken the Madagascar specimen to be the type and have placed a label on it indicating this is the holotype. The species represented by the specimens from Mahé is being described elswhere.’ The Madagascar specimen, however, did not originate from the type locality, and thus it cannot be a syntype of M. sexualis either by DISTANT (1909) or KUMAR (1974). The lectotype designation by KUMAR (1974) is therefore unjustified and in valid.

I had the opportunity to study three specimens of M. sexualis – one male and one female from BMNH, and one male from CUMZ – with the same locality labels and determination labels written most probably by the same hand (see Type material). Therefore, I regard all these specimens to be syntypes of M. sexualis . The male from CUMZ was choosen as the lectotype because it is better preserved and has the pygophore, which is lost in the male from BMNH. The Madagascar specimen designated as a lectotype by Kumar (1970) is currently described as M. distanti sp. nov.

Figures

Figs. 1-5. Mahea sexualis Distant, 1909. 1 – head, dorsal view; 2 – pronotum, dorsal view; 3 – pronotum, posterior view; 4 – abdomen of male (lectotype), ventral view; 5 – abdomen of female (paralectotype), ventral view.

Figs. 6-7. Mahea sexualis Distant, 1909. Pygophore (lectotype). 6 – posterior view; 7 – ventral view. Scale bars 0.5 mm.