Pachytomella, REUTER, 1890

Tatarnic, Nikolai J. & Cassis, Gerasimos, 2012, The Halticini of the world (Insecta: Heteroptera: Miridae: Orthotylinae): generic reclassification, phylogeny, and host plant associations, Zoological Journal of the Linnean Society 164 (3), pp. 558-658 : 626-629

PACHYTOMELLA REUTER, 1890 ( FIGS 4 , 47–48 )

Pachytoma Costa, 1842: 288 [gen. nov.; type species: Pachytoma minor Costa, 1842 , = Phytocoris passerinii Costa, 1842 by monotypy; junior homonym of Pachytoma Svains, 1840 (Mollusca) ].

Pachytomella Reuter, 1890: 253 (new name for Pachytoma Costa, 1842 ); Reuter, 1891: 37, 158 (key, descr.); Hueber, 1906: 3, 27 (key, descr.); Oshanin, 1910: 796 (cat.); Reuter, 1910: 148 (cat.); Stichel, 1933: 235 (key); Hedicke, 1935: 58 (key); China, 1943: 267 (cat.); Wagner, 1952: 96, 101 (key, descr.); Carvalho & Leston, 1952: 245 (key, fig.); Carvalho, 1952: 74 (cat.); Carvalho, 1955: 67 (key); Carvalho, 1958: 27 (cat.); Carvalho, 1958: 27 (cat.); Wagner, 1961: 49 (diag., key); Wagner & Weber, 1964: 265 (syn., descr., key); Wagner, 1973: 32 (descr., key); Schuh, 1995: 67 (world cat.).

Diagnosis: Recognized by the following combination of characters: head transverse, posterior margin wrapping around pronotum; hemelytra parallel-sided; MTG obsolete.

Redescription: Sexually dimorphic, with males macropterous or brachypterous and females brachypterous. Length = 1.5– 4 mm. Coloration ( Fig. 4 ): mostly dark brown to black, sometimes with the hemelytra partly to mostly pale, legs usually dark, sometimes partly to mostly yellow-brown or yellow. Surface and vestiture ( Figs 4 , 47A–H ): impunctate, hemelytra and posterior of pronotum rugulose. Clothed in long, decumbent, simple setae; setae on antennae and legs spinose and semi-erect interspersed with longer spines; setae on pygophore long and directed caudally. Structure: head ( Figs 4 , 47A–C ): transverse, appearing triangular from above in some species; slightly broader than anterior of pronotum, much broader than tall; genae height greater than eye height; posterior margin of vertex carinate; frons steep; eyes large and round, deflected caudally and touching pronotum; buccula thin; labium ( Fig. 47A ): LI short and broad. Antennae ( Figs 4 , 47A–C ): insertion adjacent to lower margin of eye; always shorter than body; AI as long as eye height, somewhat thicker than AII. Thorax ( Figs 4 , 47A, B, D, E ): pronotum trapezoidal, becoming subrectangular in brachypterous morphs, short, collar absent, callosite region weakly defined in macropterous morphs, obsolete in brachypterous females, lateral margins rounded, posterior margin approximately equal to head width, straight to concave; mesoscutum visible in macropterous males; scutellum broad in brachypterous morphs; metathoracic spiracle small and narrow; MTG external efferent system obsolete. Hemelytra ( Fig. 4 ): macropterous males – elongate, parallel-sided; claval commissure elongate; cuneus narrow and short; membrane with two cells, extends beyond abdomen. Brachypterous – with or without distinct clavus; without cuneus or membrane; extending partway over abdominal tergite VI. Legs ( Figs 4 , 47F ): short; metafemora incrassate in females; pretarsi without pulvilli. Abdomen ( Fig. 4 ): elongate-oval in males, broader and pearshaped in females. Male genitalia ( Figs 47G, H , 48A– D ): pygophore broad and conical; posterior margin weakly concave beneath left paramere; parameres long and slender; left paramere narrow, sensory lobe small or absent, apical apophysis sharply curved or angled, apex sometimes broadly hooked; right paramere sometimes projecting from pygophore, apical club elongate, weakly laterally deflected; phallotheca short, basally broad and weakly laterally constricted; ductus seminis attenuate, with flexible ribbing, subapically sclerotized and lacking ribbing until secondary gonopore; secondary gonopore roughly circular, usually dorsoventrally compressed (less so in Pachytomella passerini ) with distinct scalelike texturing; endosoma with or without one or two broad, sclerotized spicules. Female genitalia ( Fig. 48E, F ): sclerotized rings moderately sized, rectangular, widely separated, lateral margins and adjacent portion of DLP distinctly curved upwards; anterolateral margins of VLP sclerotized; posterior wall undivided and plate-like, mostly membranous with weak sclerotization along anterior margin; opening to vestibulum symmetrical, with lateral margins weakly sclerotized and unmodified.

Diversity and distribution: Pachytomella is a European genus of six species, which are almost exclusively found in the Mediterranean region.

Included species: Pachytomella alutacea ( Puton, 1874) Spain

Pachytomella cursitans Reuter, 1905b Spain

Pachytomella doriae (Reuter, 1884) * Spain; Tunisia

Pachytomella parallela ( Meyer-Dür, 1843) * central and north Europe

Pachytomella passerinii ( Costa, 1842) * Mediterranean

Pachytomella phoenicea ( Horváth, 1884) eastern Mediterranean

Biology and host plant associations: Limited host and biological records have been published for this genus. Two species for which host records exist are associated with high altitude: Pa. alutacea is found in high mountains under Thymus spp. and other plants, whereas Pa. parallela is found in mountain meadows on Potentilla spp. , with adults present from June to August ( Wagner, 1973). Pachytomella passerini has been collected on Potentilla sylvestris (Rosaceae) ( Kerzhner, 1964a) and Thapsia garganica (Apiaceae) ( Wagner, 1973). This species is associated with arid areas, with adults present from May to August. Pachytomella passerini overwinter as eggs ( Wagner, 1973). Pachytomella doriae has been collected on Plantago albicans (Plantaginaceae) , with adults present in May ( Wagner, 1973) ( Table 1).

Remarks: Within the Halticini , Pachytomella shares with Chorosomella , Plagiotylus , and Strongylocoris extreme reduction of the MTG, which based on our phylogenetic analysis, has occurred multiple times (character 23-1). As discussed above, Pachytomella is sister taxon to Orthocephalus , a relationship supported both in our analysis and that of Namyatova & Konstantinov (2009).

All three genera are easily distinguished by their coloration, body shape, and male and female genitalia.

Figures

Figure 4. Photographs of Halticini genera: Labops–Strongylocoris. Abbreviations: F, female; M, male.

Figure 47. Scanning electron micrograph images of Pachytomella passerini (male). A, head and thorax, lateral view; B, head and pronotum, dorsal view; C, head, anterior view; D, meso- and metathorax, lateral view; E, detail of metathorax; F, tarsus; G, pygophore, lateral view; H, pygophore, ventral view.

Figure 48. Male and female genitalia of Pachytomella passerini. A-B, aedeagus; C, left paramere; D, right paramere; E, first gonapophyses, ventral view; F, sclerotized rings, dorsal view; G, posterior wall.