Isocolus Förster, 1869
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publication ID |
https://doi.org/ 10.5252/z2014n1a3 |
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persistent identifier |
https://treatment.plazi.org/id/039087C1-F20F-FFB7-FCB7-FD9CFDAC28E1 |
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treatment provided by |
Felipe |
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scientific name |
Isocolus Förster, 1869 |
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Genus Isocolus Förster, 1869 View in CoL
TYPE SPECIES. — Diastrophus scabiosae Giraud, 1859: 368 , original designation.
DIAGNOSIS. — Morphologically the Isocolus genus is characterized by the combination of the following features: female antennae 13-15 segmented (male 14- 15 segmented), first flagellar segment (F1) shorter than second (F2), placodeal sensilla from F 2 in female (F 1 in male); radiating striae on face usually not reaching the base of the compound eyes; rough-coriaceous scutum (alutaceous on I. leuzeae ) usually with more or less conspicuous transversal carinae; rough scutellum with deep and well-defined scutellar foveae; longitudinally striated mesopleuron; forewing with glabrous or slightly pubescent margin, radial cell opened on wing margin (except in Isocolus volgensis Dyakonchuk, 1982 which it is partially open); third metasomal tergum and the following terga (as well as the hypopygium) densely punctuated (sometimes punctures also present on T2): ventral spine very short.
Isocolus melikai Pujade-Villar n. sp. ( Figs 1-3 View FIG View FIG View FIG )
HOLOTYPE. — Morata de Tajuña (Madrid, Spain), (22.VI.2011) 14.VII.2011: 1 ♀, A. Cobo, rec. ex floral capitulum of Centaurea ornata . JP-V col. (Juli Pujade- Villar’s collection deposited provisionally in UB).
PARATYPES. — Same data as holotype, 5 ♂♂, 2 ♀♀ ; Becerril de la Sierra (Madrid, Spain), (22.VII.2012) 23.VII.2012: 3 ♂♂, 5 ♀♀, A. Cobo rec., ex floral capitula of Centaurea ornata ; Valdaracete (Madrid, Spain), (06. VII.2011) 28.VII.2011: 3 ♂♂, 7 ♀♀ A. Cobo rec., ex floral capitula of Centaurea ornata . Paratypes deposited in: 4 ♂♂, 7 ♀♀ ( UB) ; 3 ♂♂, 3 ♀♀ ( INIA) ; 1 ♂, 1 ♀ ( PDL) ; 1 ♂, 1 ♀ ( USNM) ; 2 ♂, 2 ♀ ( MNHN) .
TYPE LOCALITY. — Morata de Tajuña (Madrid, Spain) situated at UTM coordinates X: 460624; Y: 4452619.
ETYMOLOGY. — This species is dedicated to our friend and colleague:George Melika (Pest Diagnostic Laboratory, Budapest, Hungary).
DIAGNOSIS. — Isocolus melikai Pujade-Villar n. sp. belongs to the Isocolus group whose females have 13-segmented antennae; the second metasomal tergum without dense white setae on the latero-basal plate, which is densely punctuated on posterior margin; mesoscutum with strong transverse carinae; mesoscutal medial line absent or slightly differentiated, sometimes forming a very short triangle. This species is similar to I. freidbergi but both species can be differentiated by: coloration (completely black in I. melikai Pujade-Villar n. sp., dark brownish with black areas in I. freidbergi ); piliferous points above the toruli and on the laterals of the scutum (present in I. melikai Pujade-Villar n. sp., absent in I. freidbergi ); distance between pronotal foveae (as long as foveae width in I. melikai Pujade-Villar n. sp., shorter in I. freidbergi ); morphology of scutellar foveae (triangular in I. melikai Pujade-Villar n. sp., rounded in I. freidbergi ); scutum sculpture (carinae more or less complete in I. melikai Pujade-Villar n. sp., interrupted carinae in I. freidbergi ); shape of propodeal carinae (very thick in I. melikai Pujade-Villar n. sp., thin in I. freidbergi ), and space between them (small in I. melikai Pujade-Villar n. sp., wide in I. freidbergi ).
DESCRIPTION
Lenght
Female: 3.8-4.5 mm (n=11).
Male: 2.7-3.5 mm (n=10).
Colour
Head, mesosoma and metasoma completely black; dark antennae, scape and pedicel black, flagellomeres brown; mandibles and clypeus from brown to black; dark legs, coxae, trochanters and basal half of femora black; apical half of femora, tibiae and tarsi yellowish brown, distal tarsi darker.
Head ( Fig. 1A, B View FIG )
In frontal view, around 1.4 times wider than high. In dorsal view, 2.1 times longer than wide, slightly narrower than mesosoma; gena slightly broadened behind compound eyes; POL 1.1 times longer than OOL and 2.2 than LOL; LOL 2.0 times longer than wide lateral ocellus; a small triangular concavity pointing in front of ocellus; frons, vertex, inter-ocelar area and occiput coriaceous, with some piliferous points; post-occiput and post-gena slightly coriaceous, with white setae, more abundant than in frons; centre of face more pubescent than frons and vertex; area between toruli and compound eye with fine coriaceous sculpture; transfacial distance 2.2 times as long as the compound eye height, 1.3 times longer than lower face height (from toruli to clypeus margin) and, 4.0 times longer than distance between antennal toruli and margin of eye; toruli diameter 2.75 times larger than inter-toruli distance. Lower part of head, in frontal view, strongly coriaceous, raised medially, with fine striae radiating to base of eye and toruli. Malar space coriaceous, 0.7 times longer than the height of the compound eye. Clypeus shiny, alutaceous, slightly higher than wide, slightly impressed, incised ventrally; tentorial foveae small but well-defined; epistomal sulcus well differentiated, widened; clypeo-pleurostomal line well differentiated.
Antenna
Female( Fig.1C, D View FIG ), 13-segmented, pedicel 1.6 times shorter than F1, F1 slightly shorter than F2; the smallest flagellomere is F10; F11 almost as long as F8+F9; placodeal sensilla from F2, although they are superficial andsparse. Antennal formula: 8: 4.5: 7.5: 7.5: 8: 8: 8: 7.5: 7: 6.5: 6.5: 6: 12.
Male antenna ( Fig. 1E, F View FIG ) similar to that of female, 14-segmented; F1 slightly curved and excavated; placodeal sensilla from F1.
Mesosoma ( Figs 1B View FIG , 2 View FIG A-C)
On lateral view, 1.1 times as long as high. Pronotum dorso-medial length 2.1-2.2 times shorter than its greater lateral margin width; pronotal sub-medial pits well differentiated, transversal, narrow and deep, separated by a space a slightly shorter than foveae width; pronotal plate carinae visible but incomplete; pronotum with white abundant setae along anterior edge, scarcer on lateral margin, fewer and shorter dorsal-medially; dorso-medial area coriaceous with some weak rugae close to the margin. Propleuron coriaceous, with some transversal rugae mainly at base. Mesoscutum around 1.3 times wider than long on dorsal view, with few, short and sparse setae. Notauli percurrent, uniformly impressed, not wider at base, alutaceous and dull; anterior parallel lines well differentiated, coriaceous and shiny, impressed on the anterior third of mesoscutum; parapsidal lines well differentiated, convergent, extending on the posterior 2/3 of the mesoscutum; medial mesoscutal line absent; area between notauli as well as between parapsidal line and notauli strongly transversally interrupted wrinkles, especially on the posterior 2/3 of the mesoscutum, more delicate to the 1/3 anterior, at the level of anterior parallel lines; inter-spaces weakly coriaceous and dull; distance separating to transversally wrinkles at least 2 times longer than their width; area between parapsidal lines and lateral edge of mesoscutum coriaceous, with some piliferous points in the anterior area; lateral edge of the mesoscutum emarginated. Mesoscutellum in dorsal view as long as wide, slightly emarginated posteriorly, uniformly rugose in arches more or less complete, interspaces coriaceous; scutellar foveae triangular, slightly longer than wide, alutaceous and shiny, anteriorly separated by a fine carina on the 1/3 anterior, its length is a bit less than the half length of the metascutellum.Dorso-axilar area shiny, rugose longitudinally. Mesopleuron transversally striated, striae weak ventrally, with short black setae in ventral part; specular area impressed; triangle of the mesopleuron dull, alutaceous and densely pubescent. Metapleuron furrow reaching the half length of the mesopleuron; upper area of the metapleuron (between metapleural furrow and propodeal spiracle) dull and rugous; axillula alutaceous, with abundant white short setae. Metascutellum weakly rugous; ventral area of metascutellum shiny, weakly rugous, triangular, occupying 2/3 of the dorsomedial area of the metascutellum; metanotal foveae alutaceous, dull, with scarce white setae. Propodeum laterally alutaceous, dull, with few long and white setae, not hiding propodeal sculpture, with some rugae basally; propodeal lateral carinae well differentiated, thick, slightly divergent anteriorly, slightly arched and wider basally; central area of propodeum shiny, alutaceous and with some rugae, glabrous; transversal propodeal spiracle with a strong carena on anterior margin; nucha with strong parallel longitudinal ridges.
Forewing ( Fig. 3F View FIG )
Shorter than the body and ciliated on margin. Radial cell opened, 2.5 times as long as wide; vein R1 uniformly pigmented, not reaching the wing margin; vein Rs not reaching the margin; triangular areola differentiated; vein Cu1b straight, with a nebulous curvature outward wing.
Legs
Tarsal claws dark, simple, without basal lobe. Metasoma ( Fig. 2D View FIG )
Second metasomal tergum exceeding in dorsal view 1/3 of the metasoma length, with few setae in the baso-lateral area, its posterior half punctuated; the following terga and hypopygium uniformly punctuate; prominent part of the hypopygial spine very short, longer than wide, with few scattered white setae.
Host
The only known host plant is Centaurea ornata Willd. (Asteraceae) .
Galls ( Fig. 3 View FIG C-E)
The galls are fused at their base (rarely scattered) and situated at the base of the floral capitula of C. ornata ; the galls are separated laterally by abundant pubescence formed by flat white setae. Each floral capitula may contain several galls (between one and five in the studied material). The galls are formed by the modification of the ovary; first, they forming a whitish cylindrical gall, with a thick wall which at the same time as the floral capitula does, turns to yellow as it is growing. The galls are elongated and elliptical (5.0-6.0 mm × 3.4-4.1 mm), green when are young and with a very rigid and smooth yellow wall in mature galls. In three capitula, galls of Urophora cuspidata (Meigen, 1826) were found coexisting with I. melikai Pujade-Villar n. sp. galls. U. cuspidata galls were usually present in high number, between one and eighteen per capitulum. These galls form a callus at the base of the receptacle and are fused. They are elongated and have a pointed upper end (4.2-7.1 mm × 3.0- 4.9 mm)( Fig. 4C, D View FIG ).
Parasitoids
An Ormyrus gratiosus (Förster, 1860) female emerged from one capitulum where I. melikai Pujade-Villar n. sp. and U. cuspidata have coexisted.
Biology
Isocolus melikai Pujade-Villar n. sp. causes galls on the capitula of C. ornata , a perennial and rhizomatous plant, endemic from the Iberian Peninsula. Capitula formation of C. ornata starts at the end of May and bloom continues until August-September.
First generation. At the time of the first collections in Morata de Tajuña and Valdaracete (late June – early July 2011) inflorescences were beginning to open and galls of I. melikai Pujade-Villar n. sp. were already formed ( Fig. 3A View FIG ). In the laboratory adults emerged from these capitula after 22 days incubation period during the mid-end of July of the same year.Althought the collected capitula were kept incubated for a whole year, no more adults emerged, and after this period of incubation, no larvae or pupae of I. melikai Pujade-Villar n. sp. were found after capitula dissection.
At a later collection in Becerril de la Sierra (late July 2012), we also observed an adult emerging only after one day incubation. A female emerged from this material was observed ovipositing on the same capitulum from which it had emerged in laboratory conditions ( Fig. 3B View FIG ). Males comprise 42 % of the total emerged adults.
Second generation. In posterior field observations at Robledo de Chavela (late July – early August 2013) females of I. melikai Pujade-Villar n. sp. were also seen ovipositing in the same plant species. Galls and larvae of I. melikai . Pujade-Villar n. sp. were found in newly formed capitula collected at the end of August in this location ( Fig. 4B View FIG ).
The number of galls, larvae and adults of I. melikai Pujade-Villar n. sp. obtained and the number and percentage of capitula infested in every location are provided in Table 1.
Distribution
So far, I. melikai Pujade-Villar n. sp. has only been found in four municipalities of the Community of Madrid where samples were taken for this study. However, surveys are needed in other areas where its host is present. The host plant, C. ornata , is an Iberian endemic species widely distributed in the
north, east and centre of the Iberian Peninsula, where it is usually found on sandy, stony and barren soils in sunny and arid areas of montane and lower altitude levels ( Willkomm & Lange 1870). A distribution map of C. ornata is available in the Spanish plants information system “Anthos” (Anthos 2012).
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