Mecyclothorax lateralis (Castelnau)

Liebherr, James K., 2018, Taxonomic review of Australian Mecyclothorax Sharp (Coleoptera, Carabidae, Moriomorphini) with special emphasis on the M. lophoides (Chaudoir) species complex, Deutsche Entomologische Zeitschrift 65 (2), pp. 177-224 : 177

Mecyclothorax lateralis (Castelnau) Figures 2J, 6A, 15A, 16A, 17A, 18A, 19A

Phorticosomus lateralis Castelnau, 1867: 92 (as Forticosomus ); Castelnau, 1868: 178.

Simodontus lateralis Chaudoir, 1873: 114 (see Nomenclatural note).

Cyclothorax lateralis Sloane, 1895: 448.

Mecyclothorax lateralis Sloane, 1903: 586.

Cyclothorax cinctipennis Blackburn, 1889: 1391 (synonymy Sloane 1895: 448).

Diagnosis

(n = 5). This large-bodied species–standardized body length 5.2-6.4 mm–is further distinguished by the rufous to brunneous body with contrasting, flavous elytral margins (Fig. 6A). The labrum is broadly and distinctly emarginate apically. The ligula is truncate apically, with the 2 apical setae separated by 4 setal diameters, the ligular surface longitudinally depressed between the setal articulations. The paraglossae are elongate, apically extended beyond the ligular apical margin twice the distance from ligular margin to their base. The pronotum is robust, transverse, with a convex disc, and depressed and circularly punctate median base (Fig. 2J); MPW/BPW = 1.45-1.56, MPW/PL = 1.35-1.40. The prosternal process is broad, only slightly depressed between the coxae, and convex anterad the coxae. The prosternal anteapical groove is deep and narrow, with only slight irregularities along its length at its deepest part. As in its sister species M. minutus , the parascutellar seta is absent. The metepisternum is abbreviated, with lateral length about 2 × maximum width, and the metathoracic wings are vestigial in examined material. The suture between visible ventrites 1 and 2 is sinuous, with the area behind markedly depressed. Microsculpture of the head is reduced, with frons glossy, vertex with indistinct transverse sculpticells; pronotal disc and median base glossy, indistinct transverse lines visible in places; elytral surface glossy with well-defined isodiametric sculpticells visible over entire surface, the apex with sculpticells more upraised; thoracic ventrites glossy, abdominal ventrites glossy medially but with isodiametric sculpticells visible in lateral depressions. Setal formula ++/++/‒2++.

Male genitalia (n = 1). Aedeagal median lobe moderately broad dorsoventrally, apex narrowly rounded and slightly projected beyond ostium (Fig. 15A); flagellar plate large and lightly sclerotized; right paramere narrow and elongate (Fig. 16A), ventral margin setose, with>20 setae along margin, setae more densely distributed in basal half; left paramere broadly subquadrate basally, apically attenuated into a whip-like apex.

Female reproductive tract (n = 1). Bursa copulatrix broadest at midlength, its surface membranous and covered with pleat-like wrinkles, apex narrowed (Fig. 17A); spermathecal duct narrow, elongate, about twice length of spermathecal reservoir; basal gonocoxite broad, 2-4 setae along apical margin (Fig. 18A), several setae along median margin; apical gonocoxite broadly rounded apically, mesal and lateral margins subparallel; a single broad lateral ensiform seta, its length about 1/3 length of apical gonocoxite; apical nematiform setae in large, apical positioned sensory furrow.

Type information.

Lectotype female (MCG) designated by Straneo (1941): specimen glued to platen // Lateralis / Cast. / Paroo riv. // Australia / Paroo River / Coll. Castelnau // LECTOTYPUS / Forticosomus / lateralis / Castelnau, 1867 / des. S.L. Straneo, 1941 [orange label] // Forticosomus / lateralis // Mecyclothorax / lateralis Cast / holotypus / Det. B.P. Moore ʽ 68 // MUSEO GENOVA / Coll. Castelnau. A female paralectotype accompanies the lectotype. It bears only the newer "Australia / Paroo River / Coll. Castelnau" label and Straneoʼs orange PARALECTOTYPUS label. As noted by Straneo (1941: 89), the paralectotype is teneral. For C. cinctipennis Blackburn, holotype (BMNH; label data not recorded): Torrens River, S.A. ( Moore et al. 1987).

Nomenclatural note. In the paragraph within which Chaudoir (1873) combined Phorticosomus minutus Castelnau with Simodontus Chaudoir (pp. 113-114), Chaudoir writes "Je crois que son Ph. lateralis est encore une espèce de Simodontus , qui mʼa semblé différente du curtulus (p. 114)." Such a statement falls short of a nomenclatural act proposing a valid new combination. Csiki (1929) interpreted Chaudoir (1873) to have officially combined Ph. lateralis with Simodontus , however his listing the page of that action as Chaudoir (1873: 113) suggests that he did not see the work personally, thus leading him to give Chaudoir credit for a nomenclatural act that Chaudoir did not commit. Sloane agreed that Chaudoir did not combine Ph. lateralis with Simodontus , writing: " Ph. lateralis is a species of Mecyclothorax . Ph. minutus , from the Paroo River, has been examined by Chaudoir, who referred it to Simodontus ... (Sloane, 1915, 462)." Mooreʼs labelling of the lectotype as holotype was corrected in Moore et al. (1987), where the presence of a paralectotype was also noted.

Distribution and habitat.

This species is distributed in interior Victoria, western New South Wales and southeastern South Australia (Fig. 19A). Localities and repositories for non-type specimens I have examined include: SA: Lucindale (MCZ, 1); Pt. Lincoln (MVM, 1); VIC: Bendigo (MVM, 1); Birchip (MVM, 1); Evansford (BMNH, 15); Lake Hattah (MVM, 1); Maldon (MVM, 1); Wedderburn (MVM, 1). These records represent beetles collected between 1911 and 1950, none with any ecological data, and so nothing can be reported with confidence concerning the ecological preference of this species: but see M. minutus below. This species is polymorphic for flight-wing configuration, with 3 brachypterous individuals observed among the 27 beetles examined; 2 of the individuals from Evansford exhibit wings that are broad, slightly more than half as long as the elytra, and without a reflexed apex. Other examined individuals have vestigialized wings, with the wing stubs shorter than the metanotum.