Mitosynum vockerothi Campbell, 1982

Makranczy, Gyoergy & Webster, Reginald P., 2016, Description of the larva of Mitosynumvockerothi Campbell, 1982, with remarks on the adult male genital morphology (Coleoptera, Staphylinidae, Oxytelinae), ZooKeys 573, pp. 257-264 : 259-260

Taxon classification Animalia Coleoptera Staphylinidae

Mitosynum vockerothi Campbell, 1982 Figs 1-7, 8-14, 15-20

Mitosynum vockerothi Campbell, 1982: 690.

Material examined.

CANADA, New Brunswick, Charlotte Co., near New River, 45.21176°N, 66.61790°W, 7.V.2007, R. P. Webster, small pond & marsh, sifting sphagnum and Polytrichum commune on hummock near margin of pond (1 ♂, HNHM; 1 ♂, 1 ♀, 2 sex undetermined, RWC), same data but 7.VII.2006 (1 ♀, HNHM; 1 sex undetermined, RWC; 1 larva L2?, CNC), same data but 16.VII.2010 (1 sex undetermined, RWC).

Partial redescription of adult morphology.

Measurements in mm (n = 8; 2 ♂, 2 ♀, 4 sex undetermined) showing size range with mean in parentheses: head width at eyes = 0.77-0.84 (0.80); head width at temples = 0.78-0.88 (0.82); maximum width of pronotum = 0.87-0.96 (0.92); approximate width of humeri = 0.84-0.92 (0.88); maximum width of abdomen = 1.09-1.21 (1.14); head length at the midline from front margin of clypeus to the beginning of neck = 0.55-0.60 (0.58); eye length = 0.25-0.29 (0.27); length of temple = 0.14-0.17 (0.16); length of pronotum at the midline = 0.67-0.74 (0.70); length of elytra from shoulder = 0.64-0.73 (0.69); length of elytra from hind apex of scutellum = 0.58-0.67 (0.61); forebody length = 1.92-2.12 (2.02); approximate body length = 3.76-4.35 (4.06). All measured from dorsal view.

Male terminalia and genitalia.

Sternite VIII apex in males almost truncate but with rounded corners. Tergite IX with strongly developed but short ventral strut. Tergite X strongly attached (Fig. 1). Aedeagus (Figs 2-5) very strongly sclerotized, dark. Apical opening processes of median lobe strong and elongate. Parameres elongate and rounded at apices. Apical part of paramere (Fig. 3) with a couple of very short peg-like setae. Internal sac with a sclerotized, symmetrical sclerite (Figs 4, 5).

Comments.

The sample size was inadequate for a statistical comparison of the size between males and females. However, there was little variation in size among individu als in any of the characters that were measured, indicating sexual dimorphism in size in this species is minimal. Sternite VIII apex in female broadly rounded but medially a little more narrowly than in males, otherwise there are no differences in external morphology between males and females.

The apical opening processes of the aedeagus and parameres very strongly resemble those in Deleaster Erichson, 1939. The presence of a few very short peg-like setae (Fig. 3) on the apical part of paramere was not previously known in Oxytelinae. The distinct, symmetrical inner sclerite is the first observation of this character within the six genera of Deleasterini sensu Makranczy (2006).

The larva of Mitosynum vockerothi

(instar unknown but presumed L2). Length (in mm): 3.00 [epicranium width (ew) = 0.61]. Body (Fig. 6) at places (e.g. dorsum of head) covered with isodiametric microsculpture, but appearing shiny with metallic luster. Head. Head capsule (Fig. 8) dorso-ventrally flattened, rounded but slightly transverse, supraantennal prominences elongate. Three stemmata in a strongly curved line (Fig. 18) appearing as lighter bumps on the sideline (Fig. 7). Ecdysial lines end in antennal foramen and a 'glandular area’ ( Newton 1982) is observed posterior to the latter. Dorsum of head with frontal setae (frontal dorsal = fd, frontal lateral = fl, frontal marginal = fm), epicranial setae (epicranial dorsal = ed, epicranial lateral = el, epicranial marginal = em), temporal (t), lateral (l) and posterior setae (p). Antenna (Fig. 17) three segmented, three sensory appendages (sa) on penultimate article, four solenidia (so) on apical. Labrum (Fig. 11) medially trapeziform, laterally transversely elongate, frontal margin with two pairs of stout setae. (Note: The labrum in the examined larva appears to be teratological; only the healthy part is considered and is mostly mirrored for the drawing.) Mandible (Fig. 16) triangular shaped but thick at base, gradually narrowing toward quadrifurcate apex; apical teeth in close proximity. Maxilla (Fig. 15) with cardo (cdo) subtriangular, stipes (stp) apically slightly broadening, with mala (ma) forming an almost uniform plate, palpifer (pf) distinct, maxillary palp three segmented, third palpomere (pm) with digitiform sensory appendage at base. Labium (Fig. 12) with mentum (mnt) subrectangular, slightly transverse, posterior corners rounded, ligula (lg) fused with prementum (pmnt), submentum (smnt) quite elongate, parallel sided, labial palp (lp) two segmented. Thorax. Tergites with short and long setae arranged more or less along transversal lines; pronotum as in Fig. 9, mesonotum as in Fig. 10, metanotum with setation identical to that of mesonotum. Pronotal discal setae in rows (a-d). Legs with five articles, coxa (cx) rhomboid, trochanter (tr) with a few campaniform sensilla on both sides, femur (fm) with a few scattered pores, tibia (tb) with one pore, apically one tiny spine, tarsungulus (tu) with two small setae in basal position, one on each side. Anterior leg as in Fig. 13. Abdomen. Segments I-VIII composed of tergites and sternites. First tergum with spiracles at its sides (Fig. 14) in the intersegmental membrane, segments II–VIII with spiracles in tergites (Fig. 19). Abdominal segments IX and X (Fig. 19) with dorsal and ventral sclerites fused. Urogomphi (Figs 19-20) one articled, very short, almost vestigial. Anal lobes not everted in examined specimen but without conspicuous structures.