Mesosaimia robusta Breuning, 1938

Yamasako, Junsuke, 2014, Review of the genus Mesosaimia Breuning with description of a new species (Coleoptera: Cerambycidae: Lamiinae: Mesosini), Zootaxa 3852 (4), pp. 461-474 : 463-466

Mesosaimia robusta Breuning, 1938

( Figs 1–4 , 16–17 , 23–29 , Pl. 1)

Mesosaimia robusta Breuning, 1938: 207 ,

type locality: India, Sibsagur, Nambor Range , Assam .

Type material examined. Lectotype ( BMNH, dissected and remounted by J. Yamasako, 2013, Figs 1–2 , 16 , 23–29 ): ♂, “Nambor R. Sib.”/ sagar, Assam / C. F. C. Beeson. / 15. V. 21.”, “ Mesosaimia / robusta mihi / Typ / det. Breuning”, “ Type ”, “Brit. Mus. / 1937-319.”, “173” . Paralectotype: 1♀ ( NHMB, Figs 3–4 , 17 ), “ Assam ”, “ Mesosaimia / robusta / mihi Paratyp / det. Breuning ” .

Differential diagnosis. This species is easily distinguishable from congeners by distinct swellings on pronotum, dominant brown pubescence of elytra and distinct longitudinal swellings behind elytral bases.

Redescription. Male (n = 1, Figs 1–2 , 16 ): Length from vertex to elytral apices 19.0 mm, width across humeri 7.9 mm.

Body black except pedicel to antennomere 11 which are reddish brown; head, pronotum and elytra with mottled brown, light brown and black pubescence of which black ones are forming small spots scattered throughout; ventral surface with mottled light brown and brown pubescence. Head with pair of longitudinal narrow black bands on occiput behind upper eye lobes. Antennae with scape annulate with brown pubescence except for apex, sparsely scattered with small black spots; pedicel with light brown pubescence; antennomeres 3–11 annulate with same pubescence on each basal part and the remainders clothed with brown pubescence. Pronotum with pair of interrupted longitudinal narrow black bands on disk, a transverse narrow indistinct band on each lateral side. Elytra with several patches of black pubescence transversely arranged on basal 1/3 and behind middle. Legs with femora covered with brown pubescence; tibiae with brown pubescence except before middle and apical part; tarsomeres 1–3 and basal half of claw clothed with brown pubescence.

Head with frons having sparse, indistinct and fine punctures; upper and lower eye lobes connected by single row of ommatidia; lower eye lobe 1.0 times as long as width, 0.7 times as long as gena. Antennae 1.7 times as long as body length, surpassing elytral apices near middle of antennomere 6; scape to antennomere 5 sparsely fringed beneath by suberect setae; antennomere 11 with suberect setae in apical 1/3; relative lengths of each segment as follows: 1.2: 0.2: 1.7: 1.3: 1.1: 0.9: 0.8: 0.8: 0.7: 0.7: 0.7. Pronotum widest near middle, 0.8 times as long as width, 0.7 times as wide as elytral base; disk with pair of two humped distinct swellings, with sparse punctures shallow and indistinct in apical half, distinct and umbilicate in basal half. Elytra 0.7 times as long as body length, 1.6 times as long as width at humeri, provided with several distinct granules in basal 1/4, swollen longitudinally near middle behind base, with sparse punctures distinct in basal half, reduced apically and almost disappearing in apical half; sides slightly narrowed straightly toward apical 1/4, arcuately narrowed apically; apices round with sub-quadrate inner angle.

Male genitalia (n = 1, Figs 23–29 ): Tegmen with lateral lobe thick and slightly short, almost 1/4 of the total length of tegmen, widest at base, gently narrowed toward apical half, becoming straight and dilated toward rounded apex, with setae that arise from apical half of latero-ventral side, denser and longer apically, concentrated near apex, with minute setae on basal part of ventral side. Median lobe with apex acuminate in ventral view; median struts dehiscent from just behind middle. Endophallus almost triple length as median lobe; BPH slightly longer than half length of median lobe; MT+CT about twice as long as median lobe; PB about half length of median lobe. MT+CT gently curved dorsally in basal 1/5, becoming reflexed ventrally near base; APH weakly developed, roundly swollen in basal part. MSp sparsely distributed in apical half of MT+CT; LSp evenly arranged from basal half to basal 1/5 of MT+CT; SSp evenly and densely distributed in apical half of PB.

Female (n = 1, Figs 3–4 , 17 ): Length from vertex to elytral apices 16.2 mm, width across humeri 6.5 mm.

Similar to male, but body more rotund. Head with lower eye lobe 1.1 times as long as width, 0.8 times as long as gena. Antennae 1.0 times as long as body length; scape to antennomere 4 sparsely fringed beneath with suberect setae; antennomere 11 short and bullet shaped; relative lengths of segments as follows: 1.9: 0.4: 2.4: 1.5: 0.8: 0.7: 0.5: 0.5: 0.5: 0.4: 0.4.

Distribution (Pl. 1). India (Assam Prov.)

Taxonomical notes. According to Breuning (1938, 1939), this species has transverse lower eye lobe. It is one of the important characteristics that define the genus. However, on examining the type material, the length is subequal to width in the male, and slightly longer vertically in the female.

Breuning (1938) deposited only one syntype in BMNH, but he referred to sexual dimorphism in the original description. Recently, I found a female specimen deposited in MHNB which has a label handwritten as " paratype " by Breuning, and it is quite plausible to be another syntype. Therefore, I designate the lectotype and the paralectotype as above in order to stabilize the taxonomy and facilitate further identifications of this species.

Figures

FIGURES 1 – 8. Habitus of Mesosaimia spp. 1 – 2. Mesosaimia robusta (male, lectotype); 3 – 4. ditto (female, paralectotype); 5 – 6. M. similis (male); 7 – 8. ditto (female); 1, 3, 5, 7. dorsal view; 2, 4, 6, 8. lateral view.

FIGURES 16 – 22. Frontal views of Mesosaimia spp. 16 – 17. Mesosaimia robusta; 18 – 19. M. similis; 20. M. mausoni; 21 – 22. M. wakaharai; 16, 18, 21. male; 17, 19, 20, 22. female; 16. lectotype, 17. paralectotype, 20, 21. holotype; 22. paratype.

FIGURES 23 – 29. Male genitalia of Mesosaimia robusta (lectotype). 23. Tegmen in dorsal view; 24. ditto in lateral view; 25. lateral lobes in ventral view; 26. median lobe with CS in dorsal view; 27. ditto in lateral view; 28. apex of median lobe in ventral view; 29. median lobe with fully inflated endophallus without eversion in lateral view. Scale = 1.0 mm. See text for abbreviations.