Isthmiade planifrons Zajciw, 1972

Clarke 1, Robin O. S., 2009, Bolivian Rhinotragini II: ISTHMIADE Thomson, 1864 (Coleoptera, Cerambycidae), with two new species Robin O. S. Clarke, Papéis Avulsos de Zoologia 49 (44), pp. 577-591 : 587-589

Isthmiade planifrons Zajciw, 1972

( Figs. 5A, 5B )

Isthmiade planifrons Zajciw, 1972a: 137 ; 1972b: 581; 1974 a: 57 (distr.); Julio et al., 2000: 17 (holotype); Monné, 2006: 483 (cat.).

Diagnosis: Because of its small size Isthmiade planifrons cannot be confused with any other Bolivian species. The strongly outlined, shorter, cuneiform elytra and dark legs are also characteristic.

Redescription: Male g eneral colour: opaque, chestnut to black. Head, entire mandible and scutellum black; sterna black, except sides and disc of pronotum broadly, and mesepisterna orange-red. Scape, pedicel, antennomere III, IV and basal half of V black, the rest brown. Elytra translucent ochraceous except area around scutellum and apical 1/4 rufous, sutural and lateral borders and epipleuron (except adjacent to humeri) black. Abdomen orange, apical half of urosternite V blackish, apex of abdominal process cream. Legs chestnut, darkest on coxae, femoral clubs and dorsad of protibia; protibia orange, dorsad black; apex of profemoral club slightly orange; peduncles of meso- and metafemora orange; protarsus brown, basal mesotarsomeres paler, III chestnut, onychium black, metatarsus entirely black. Wings uniformly dusky for apical half.

General pubescence: body hirsute, becoming dense in front of prosternal process, and all of metasternum and metepisternum. Short, recumbent pubescence on rostrum. Submentum and gula almost glabrous, sparsely hirsute at sides, without specialised group of large setae. Patches of dense, longer, recumbent, glistening white pubescence on sides of pronotum (adjacent to coxal cavities, and associated with sexual puncturation), mesosternum, mesepimeron, basal half and line down middle of metasternum, base and apex of metepisternum, and metacoxae. Abdomen sparsely hirsute, denser at sides and apex.

Surface ornamentation: labrum with arc of six moderately large punctures on basal half, clypeus and frons between inferior lobes impunctate; frontal suture distinct to hind margin of antennal tubercles; vertex with smooth, impunctate line at middle, otherwise closely and irregularly punctured with large and small punctures between, and adjacent to, hind margin of superior lobes; submentum with indistinct carinas and mixture of scattered small and large punctures, gula impunctate. Prothorax anterior to prosternal process transversely striate and micro-punctate with scattered large punctures, apex of prosternal process densely micro-punctate; pronotal disc sparsely punctured with mixture of 32 larger and smaller punctures, median line narrow and impunctate; sides with scattered small and large punctures, sexual puncturation represented by patch where the surface is densely micropunctate and overlain by pubescence (as mentioned above). Mesosternum rugose, with very dense, fine punctures; elytra with confused band of moderately large, isolated punctures running from shoulders and spreading on to disc after basal half, rest of disc with sparse, shallow punctures; sides with single line of large close punctures from basal third to apex. Metasternum with rows of dense, small, reticulate punctures radiating from midline, these rows covering basal half and midline to apex. Abdomen almost impunctate and very shiny; urosternite V with uniform, moderately dense, small punctures.

Structure: Head. Rostrum distinctly short, lengths of gena/inferior lobe 0.25/ 0.70 mm; frons separated from clypeus by shallow declivity; frontal suture lying in V-shaped depression, distinct to back of antennal tubercles; inferior lobes almost contiguous, interocular distance/width of lobe 0.1/ 0.6 mm; superior lobes proximate, interocular distance/width of lobe 0.30/ 0.15 mm. Antenna long and slender, reaching middle of urosternite III; scape pyriform (0.5 mm) almost three times longer than pedicel (0.2 mm); antennomere III (0.9 mm) the longest; antennomere IV (0.5 mm), V (0.8 mm) nearly as long as three, subequal to VI and VII (both 0.75 mm), remaining antennomeres gradually shortening to X (0.5 mm), X1 (0.6 mm).

Thorax. Prothorax distinctly longer (1.6 mm) than width of front/hind margins (1.2/ 1.3 mm), deeply constricted at base and apex, the sides strongly rounded and widest (1.4 mm) at middle; disc of pronotum not strongly raised, with two prominent calli just in front of middle and two less prominent calli just behind middle, these separated by elongate callus at midline; prosternal process flat, base narrow (1/9 width of coxal cavity) and elongate, apex large and triangular, not declivous across middle, the margins narrow and elevated, but not explanate.

Mesothorax abruptly declivous before mesosternal process, the latter moderately broad at base (1/4 width of coxal cavity), apex slightly wider, outer angles prominent.

Scutellum subtriangular, apex bifid. Elytra strongly outlined by thickening of elevated margin between upper surface and epipleuron; relatively short and broad (2.1 times width of humeri), reaching apex of urosternite I, narrowing regularly to apex, apical third strongly dehiscent; humero-apical costa only traceable from middle to apex, giving elytron a distinctive flat appearance; apices not lobed, truncate, very slightly oblique, both inner and outer angles minutely toothed.

Metasternum tumid and convex (slightly flattened on disc and planar with pro- and mesocoxae); longitudinal suture strongly impressed from base to apex.

Legs moderately robust, profemora with short peduncle and tumid clave; mesofemoral peduncle and clave longer; hind leg long (3.3 mm), gradually thickening from base to near apex. Tarsi not robust, but relatively long, metatarsus 1.9 mm; metatarsomeres I (0.7 mm) longer than II (0.3 mm) and III (0.25 mm) together.

Abdomen. Long and narrow, with transverse, beadlike segments. Urosternite I longest (1.2 mm), narrow with subparallel sides, urosternites II (0.9 mm) and III (1.0 mm) strongly rounded at sides, IV (0.9 mm) subparallel, V (0.7 mm) trapezoidal with sides slightly “winged” and deep depression on apical half; abdominal process short, triangular, whitish at apex.

Variation: Colour generally may become paler and less contrasting, especially that of elytra and legs, the latter sometimes entirely brownish-orange; distribution of red and black is variable (sterna, including pronotum, may be entirely black but not entirely red; abdomen may be entirely black). Punctures on labrum may be reduced to four large ones, or as many as 12 smaller ones; punctures on disc of pronotum may be reduced, or become very large (0.1 mm diameter) to form a compact group. Antennae may be shorter, reaching base of urosternite III, and elytra longer reaching middle of II. Apical triangle of prosternal process may be declivous across middle; pronotum varies from 1.13-1.23 longer than wide. Elytral dehiscence stronger or weaker, apices may reach basal third of urosternite II, and may be more acuminate and truncate, outer angles rounded or with distinct small teeth.

Female: Colour distribution of the females show no significant difference from the male except for: black fascia at base of pronotum may be trident-shaped; abdomen tends to be darker, even blackish, and abdominal process same colour as rest of abdomen.

Pubescence in general reduced, hirsute patch in front of prosternal process absent; patches of dense white pubescence reduced especially on prothorax and metasternum, but still entire on mesepimeron, and dense patch of recumbent pubescence adjacent to procoxal cavities small. Punctures on disc of pronotum very variable, from 10-34 larger punctures; and calli more distinct in larger females.

Sexual dimorphism: rostrum longer, length gena/length inferior lobe 0.4/ 0.5 mm; distance between inferior lobes/width of lobe 0.35/ 0.55 mm, interocular space somewhat elevated, flat, lacking carinas, with one or two irregular rows of smaller and larger punctures to either side of midline; frontal suture relatively broad, well marked from clypeus to behind antennal tubercles, from where it continues to back of occiput as a narrow, impunctate carina. Antennae shorter, in most females reaching apical 1/3 of urosternite II. Elytra more strongly dehiscent, diverging from middle, length rather variable, reaching from apex of urosternite I to middle of II; apical teeth generally larger. Metasternum less tumid than male, planar with procoxae, more salient than mesocoxae; smooth, with sparse punctures, not at all reticulate, metasternal suture may be less impressed and not entire. Metasternum. Abdomen fusiform, urosternites with slightly different proportions: I long (1.5 mm), II (1.2 mm) longer than III (1.1 mm), IV (0.9 mm), V (0.8 mm) black, moderately conical, regularly convex, apex rounded.

Measurements (mm): 25 males / 8 females respectively: total length 7.2-10.7/8.9-10.9; length of pronotum 1.2-1.7/1.5-2.0; width of pronotum 1.1-1.5/1.3-1.8; length of elytra 2.6-3.6/3.4-4.6; width at humeri 1.2-1.7/1.6-2.2.

Material examined (in the RCSZ collection): The following with the same data and collectors, different flower hosts: BOLIVIA,SantaCruz,17°29’96”S/ 63°39’13”W, 420 m, Hotel Flora & Fauna, 5 km SSE Buena Vista, R. Clarke/S. Zamalloa col. The following on/flying to flowers of “Barbasquillo” vine: 1 male 2.VIII.2005, 1 female 22.VIII.2005, 1 female 23.VIII.2005, 1 female 27.VIII.2005, 1 male 30.VIII.2005, 1 male 9.X.2004, 1 male (ex.1a) and 1 female (ex.1b) in coitus 8.X.2005, 4 males 3. IX.2005, 1 male 4.IX.2005,1 male 9.IX.2005, 1 male 27.IX.2005, 1 male 2.VIII.2007. The following on/flying to flowers of “ Piton amarillo” : 1 female 11.X.2005, 1 male 20.X.2005, 1 male 25.X.2005. The following on/flying to flowers of “ Sama blanca chica” : 1 male 7.X.2005, 1 male (ex. 2a) and 1 female (ex. 2b) in coitus 8.X.2005, 1 male 21.X.2005, 1 female 18.IX.2007. The following on/flying to different flowers: 1 male 3.IX.2005 on “Mango”; 1 male 9.X.2004 on “Turere”; 1 male 2.X.2005 on “Laguno”; 1 male 26.X.2005 on “Sama blanca”; 2 males 15.VIII.2007 and 9.VIII.2008 on Gomphrena vaga ; 1 male, 13.VIII.2008 on “Ramoneo”; 1 male, 27.VIII.2008 on “Sapaimosi”. The following flying to white light: 1 male 23.IX.2005. The following collected at different localities: Rancho El Cairo, 5 km W Buena Vista , 1 female 30.VIII.2005, R. Clarke / S. Zamalloa col., on/flying to flowers of “Barbasquillo” vine. Road to Potrerito village, 4 km W of Buena Vista, 440 m, 9.VIII.2008 , R. Clarke & S. Zamalloa col., on/flying to flowers of Gomphrena vaga Mart.

Discussion: Monné & Hovore (2006) record this species from Espírito Santa, Brazil. Since Wappes et al. (2006) did not list I. planifrons for Bolivia, these records represent a new record for this country and a considerable range extension for the species.

Figures

FIGURAS 1‑5: Bolivian species of Isthmiade Thomson, 1864. 1. Isthmiade laevicollis Tippmann, 1953, 1A female 1B male; 2. Isthmiade zamalloae sp. nov., 2A male holotype, 2B female; 3. Isthmiade ichneumoniformis Bates, 1870, 3A male, 3B female; 4. Isthmiade martinsi sp. nov., 4A male holotype; 5. Isthmiade planifrons Zajciw, 1972, 5A male, 5B female.