Mecyclothorax minutus (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 minutus (Castelnau) Figures 2K, 6B, 15B, 16B, 17B, 18B, 19B

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

Simodontus minutus Chaudoir, 1873: 113.

Mecyclothorax minutus Csiki, 1929: 488.

Cyclothorax fortis Blackburn, 1889: 1390 (NEW SYNONYMY).

Mecyclothorax fortis Sloane, 1903: 486.

Diagnosis

(n = 5). This species shares the rufous to brunneous body color (Fig. 6 A–B) and lack of the parascutellar seta with M. lateralis , however the beetles are smaller–standardized body length 4.9-5.7 mm–and the elytral lateral and apical margins do not markedly contrast with the elytral disc. In teneral individuals the margins may appear somewhat paler, partly due to reflection of the underlying abdominal tergites through the cuticle, and partly due to a smoky infuscation of the median elytral disc. However, the difference in coloration from disc to margin is gradual, never marked. Males exhibit 2 setae each side of the apical ventrite margin, for a total of 4 apical setae, differing from M. lateralis which retains the plesiomorphic single seta per side: i.e. a total of 2 apical abdominal setae. The labrum is distinctly emarginate apically, the 2 sides subangulate medially. 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 elongate, extending twice as far beyond the ligular apical margin as the distance from paraglossal base to ligular margin. The pronotum is transverse, with the depressed median base margined at the disc with strigose punctures (Fig. 2K); MPW/BPW = 1.47-1.56, MPW/PL = 1.42-1.51. The prosternal process is broad and only slightly depressed between the coxae, convex anterad the coxae. The prosternal anteapical groove is deep and narrow, smooth at depth. As in M. lateralis , 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 a broad circular depressed area posterad the sinuosity. Microsculpture of the head is reduced, with frons and vertex glossy, the surface interrupted only by scattered micropunctures. Similarly the pronotal disc and median base are glossy, with indistinct transverse lines visible in places. The elytral surface is glossy with micropunctures covering the surface of the disc, the apex with margins of transverse sculpticells upraised. Ventrally, the thoracic ventrites are glossy; abdominal ventrites glossy medially but with swirling transverse sculpticells visible in lateral depressions. Setal formula ++/++/‒2++.

Male genitalia (n = 1). Aedeagal median lobe moderately broad dorsoventrally, apex narrowly rounded and not projected beyond ostium (Fig. 15B); flagellar plate large and lightly sclerotized; Right paramere narrow, elongate,>20 setae along ventral margin, setae more densely packed in basal half, dorsal margin with ~4 small setae (Fig. 16B); left paramere slightly broadened basally, evenly narrowed to apex.

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

Type information.

For P. minutus , lectotype female (MCG) designated by Straneo (1941): specimen glued onto elongate trapezoidal point // riv. N.H. / Murray [blue label] // minutus / Cast. // N(ova) Hollandia / Riv. Murray / Coll. Castelnau // Forticosomus / minutus / Cast. // LECTOTYPUS / Forticosomus / minutus / Castelnau, 1867 / des. S.L. Straneo, 1941 // Mecyclothorax / minutus Cast / holotypus / Det. B.P. Moore ʽ 68 // MUSEO GENOVA / Coll. Castelnau. Mooreʼs labelling of this specimen as holotype, as done for M. lateralis above, is corrected in Moore et al. (1987) to reflect Castelnauʼs lack of mention of how many specimens from Paroo River were before him at description. For C. fortis Blackburn, lectotype male (BMNH) hereby designated: specimen mounted on white card with "913 T" on obverse, black and red lines at base, the red crossed by two triangles // round, red-margined Type label // Blackburn Coll. / 1910-236 // Cyclothorax fortis , Blackb. // Lectotype / Cyclothorax / fortis / Blackburn / J.K. Liebherr 2006 (black-margined red label). Female paralectotype (SAMA): specimen card-mounted with ventral surface upward, card with black and red line, “913” in red ink // S. Australia / Blackburn // Cyclothorax / fortis , Bl / Co-type // Paralectotype ♀ / Cyclothorax / fortis Blackburn / det. J.K. Liebherr 2004 [black margined, red label]. The lectotype (BMNH) was assigned based on its occupation of the first locality, Port Lincoln, mentioned in Blackburnʼs description ( Blackburn 1889: 1391), with the paralectotype assigned to the second locality mentioned by Blackburn; "Yorkeʼs Peninsula." Thus Port Lincoln becomes the type locality for the Blackburn name.

Distribution and habitat.

This species exhibits a bicentric distribution, occupying the interiors of Western Australia, and New South Wales, South Australia and Victoria (Fig. 19B). Distributional records and institutional repositories for examined non-type specimens include: NSW: Bogan R. (MCZ, 1); Lake Urana Nat. Res. (EMEC, 17); SA: Koongawa, 4 mi. ESE (ANIC, 1); Pt. Augusta (BPBM, 7); Birchip (MVM, 1); Mallee Dist. (MVM, 3); Nyah (MVM, 1); WA: Burracoppin, 129 mi. S (WAM, 1); Coongardie, 85 km W (BPBM, 3); Hineʼs Hill, 10 mi. SW Merredin (CAS, 4); Hughden Rock (WAM, 2); Mullewa (MCM, 1; MCZ, 10); Newman Rock (ANIC, 1); Ravensthorpe, 50 mi. E (CAS, 1); Southern Cross, 14 mi. W (CAS, 1); Yellowdine, 18 km S (UASM, 2). Beetles constituting the sizable series collected by K.W. Will at Lake Urana Nature Reserve were found under rocks near pools of water in forest, by headlamp at night. As with most carabid beetles living in dry habitats, such nighttime entomological activity is a requisite for obtaining more than the odd specimen. Given the close, adelphotaxon relationship between M. minutus and M. lateralis , this type of habitat is suggested as the situation within which to find M. lateralis as well.