Diastolinus insularis ( Champion, 1896 )

Hart, Charles J. & Ivie, Michael A., 2016, A Revision of the Genus Diastolinus Mulsant and Rey (Coleoptera: Tenebrionidae), The Coleopterists Bulletin 70 (3), pp. 485-540 : 485-540

Diastolinus insularis ( Champion, 1896)

( Figs. 86–91 , 106 )

Ctesicles insularis Champion 1896: 7 (type locality: St. Vincent); Leng and Mutchler 1914: 461 ( St. Vincent); Gebien 1938: 401 [438] (Lesser Antilles); Blackwelder 1945: 524 ( St. Vincent); Marcuzzi 1977: 25 (in part, St. Vincent records only), 1984: 79 (in part, St. Vincent records only), 2001: 251 (in part, St. Vincent records only); Peck 2010: 46 (in part, St. Vincent records only), 2011b: 29 (in part, St. Vincent records only), 2016: 159 (in part, St. Vincent records only); Soldati and Touroult 2014: 99 (in part, St. Vincent records only).

Type Material. Champion did not designate a type. Among the syntypes, the first of these listed is hereby designated the lectoype, the remainders as paralectotypes, and they are so labeled: Windward side; St. Vincent, W.I.; H.H. Smith.; 254/ W. Indies.; 96-98/ Ctesicles ; insularis Ch. ; ♂ / Syntype / WIBF 035656/ LECTOTYPE; Ctesicles ; insularis ; Champion 1896 (1 BMNH). Windward side; St. Vincent, W.I.; H.H. Smith./ W. Indies.; 96-98/ Ctesicles ; insularis Ch. / near lot 14 May (Windward); this species is found under stones; and dry leaves along the sea-shore. (sandy)/ Syntype /WIBF 035657/ PARALECTOTYPE; Ctesicles ; insularis ; Champion 1896 (1 female, BMNH). St. Vincent, W.I.; H.H. Smith.; 5/ W. Indies.; 96-98/ Ctesicles ; insularis Ch. ; ♂ / Syntype / WIBF 035658/ PARALECTOTYPE; Ctesicles ; insularis ; Champion 1896 (1 BMNH). St. Vincent, W.I.; H.H. Smith.; 5/ W. Indies.; 96-98/ Ctesicles ; insularis Ch. ; ♀ / Syntype / WIBF 0356569/ PARALECTOTYPE; Ctesicles ; insularis ; Champion 1896 (1 BMNH).

Diagnosis. This species can be distinguished by its small size (6.0 mm or less), large punctures covering the entire body surface, upper surface covered with yellow pubescence, deeply impressed strial puncation with punctures commonly interrupting and overflowing onto the interstriae, shiny, narrow elytral intervals, and male aedeagus with parameres that have a nearly straight apical margin.

Redescription. Male. Length 5.3–5.8 mm, width 2.3–2.5 mm. Body ( Fig. 86 ) black, except antennae pitchy red, last 3–4 antennomeres testaceous, sometimes tarsi reddish; upper surface dull, except elytral intervals somewhat shiny, venter shiny; ovate-oblong; moderately convex; scattered, yellow setae covering body.

Head ( Figs. 86, 87 ) with epistoma flattened; punctures greater than diameter of ommatidium, covering dorsal surface, spaced less than 1X puncture diameter; setae 1.5–2.0X length of punctures. Labrum densely punctate, punctation smaller than that on frons. Antenna clavate. Dorsal and ventral portions of eye somwhate oblong-ovate, roughly equal in size and shape. Gular horns short, not prominent.

Pronotum ( Fig. 87 ) widest at anterior 1/3, anterior width equal to basal width; apical margin evenly, broadly emarginate; apical corners rounded, lateral margin widened from apex to anterior 1/3, then sides gradually narrowed to base; basal width narrower than width across humeri; basal margin bisinuate; dorsal surface broadly, evenly convex; all margins narrowly beaded, except obsolete at middle of anterior margin and middle of posterior margin; heavily punctate, puncture diameter equal to that of punctures on head, spaced much less than 1X puncture diameter on pronotal disc, almost confluent; distinct yellow, recumbent setae originating from punctures. Hypomeron covered in deep punctures. Prosternal process short, bluntly rounded, punctate, with scattered, yellowish, semi-erect setae.

Scutellum ( Fig. 87 ) small, rounded, about 3X wider than long. Elytron ( Figs. 87, 88 ) broadening from base to widest point opposite metaventrite, then evenly arcuate to apices; striae deeply impressed; strial punctures deep, often confluent, interrupting interstrial line; intervals narrowly convex, punctation minute. Stria 7 ending in lateral stria at humeral angle.

Mesoventrite punctate. Metaventrite short, punctate on anterior border behind mesocoxae.

Leg ( Fig. 88 ) surfaces setose and heavily punctate. Profemora somewhat expanded and clavate. Protibia narrow, expanding gradually distally; dorsolateral margin nearly straight; posteroventral surface with stout spines on apical 2/3; apex obliquely truncate, ringed by stout spines. Protarsus with tarsomeres 1–3 expanded, ventrally with golden, densely setose pads, tarsomere 2 widest, 1.5X width of tarsomere 4. Mesotarsus with tarsomeres 1–3 weakly expanded, ventrally with densely setose pads. Metatarsus narrow, subequal in length to metatibia, without setose pads; 1 st tarsomere more than 1.5X length of 2 nd.

Abdominal ventrites ( Fig. 89 ) heavily punctate; covered in semi-erect, yellowish setae; ventrites 1–2 flattened medially; anterior border of ventrite 1, just behind hind coxae, with row of heavy confluent punctures; ventrite 5 flattened medially, posterior margin evenly rounded. Aedeagus ( Figs. 90, 91 ) with basal piece and parameres arched, about 1/2 elytral length; parameres parallel in basal 1/2, then slightly widened and gently rounded to apex, apical margin almost straight; parameres with weakly sinuate lateral margin, without upturned tips in lateral view.

Female. Length 5.5–6.0 mm, width 2.4– 2.6 mm. Similar to male except body typically larger, more ovate and robust than male. Pro- and mesotarsi not expanded. Abdominal ventrites 1– 3 slightly convex medially; ventrite 5 slightly convex.

Biology. This species has been found under stones and dry leaves near the seashore.

Distribution. St. Vincent ( Fig. 106 ).

Figures

Figs. 86–91. Diastolinus insularis, lectotype. 86) Dorsal habitus; 87) Pronotum; 88) Lateral habitus; 89) Abdominal ventrites; 90) Aedeagus, dorsal view; 91) Aedeagus, lateral view.

Fig. 106. Map of the distributions of Diastolinus species in the Lesser Antilles.