Agnosthaetus minutus Clarke, 2011

Clarke, Dave J., 2011, A Revision of the New Zealand Endemic Rove Beetle Genus Agnosthaetus Bernhauer (Coleoptera: Staphylinidae), The Coleopterists Bulletin (mo 10) 2011, pp. 1-118 : 55-56

(23) Agnosthaetus minutus Clarke , new species

( Figs. 156 , 159 , Map 5 )

Type Material. Holotype. ♂, with four labels: “ New Zealand RI| Wharite , nr smt [summit; 40°15′S 175°51′E]| 23 Oct 1993 / JT Nunn| collection/ FMNH- INS 0000 019 681 / HOLOTYPE Agnosthaetus minutus Clarke , ♂, design. D. Clarke 2011”, in JTNC . Paratype. 1 specimen (1♂). Same data as holotype, FMNH-INS 48487, in JTNC. Both the holotype and paratype were originally mounted on separate cards on the same pin; both have been remounted on points on separate pins .

Diagnosis. Agnosthaetus minutus can be distinguished from all other Agnosthaetus species by the combination of short temples (less than 50% EYL), presence of microsculpture only on the dorsum of the head anterior to the dorsal tentorial sulci, elongate and straight pronotal medial sulcus continuous with the basal fovea ( Fig. 23 , ms, bf), two lateral elytral ridges ( Fig. 24 , ek, mr), and fully developed metathoracic pleural ridge ( Fig. 24 , mp).

Description. Color: More or less uniformly reddish brown. Head: Frontal ridge absent. Dorsum moderately densely punctate; with punctures distributed anteriorly, laterally, and posteriorly on disc, middle part impunctate. Punctures deep, but indistinctly defined; diameter greater than diameter of eye facet; interpuncture distance anteriorly less than half puncture diameter, posterolaterally subequal to or greater than puncture diameter. Dorsal microsculpture present only anterior to dorsal tentorial sulci; faintly reticulate. Dorsal tentorial sulcus (cf. Figs. 10–11 , dt) narrowly ovate; width subequal to or slightly greater than puncture diameter. Sublongitudinal ridge (cf. Fig. 10 , sr) distinct; not confused by smaller carinae or punctures; crest at antennal tubercle with distinct microsculpture. Area above and behind antenno-ocular carina ( Figs. 10–11 , arrow) with distinct subsidiary carina formed by confluent punctures. Antennoocular carina joining eye at about middle. Temple ( Fig. 11 , tm) short, less than 50% EYL. Subocular surface more or less evenly microsculptured (cf. Fig. 65 ). Apical labral margin in males moderately broadly and shallowly emarginate medially, evenly dentate, with 19–23 teeth (n =2), with medial row of dorsally projecting teeth, occasionally fused into single broad tooth. Adoral labral surface in males with subapical, transverse ridge. Mandible sexually dimorphic; males with single, dorsally directed tooth, without preapical spur (cf. Fig. 189 ) or with weakly developed preapical spur (cf. Fig. 190 , arrow); females with single, mesially projecting tooth, without spur. Mentum smooth, unmodified (cf. Fig. 67 ). Prothorax: Pronotum without microsculpture. Medial pronotal sulci anteriorly separate from and terminating posterior to anterior punctures or continuous with anterior punctures (cf. Fig. 76 ). Distance between medial sulci subequal along entire length, or slightly greater posteriorly. Pronotal basolateral carina present, but only weakly developed (cf. Fig. 76 , bp). Anterior pronotal puncture (cf. Fig. 70 , ap) indistinct; medial puncture (cf. Fig. 70 , mu) distinct; basal puncture ( Fig. 70 , bu) indistinct. Medial pronotal seta subequidistant from medial and lateral sulci (cf. Fig. 76 ). Pronotal hypomeron ( Fig. 24 , hy) shiny, without microsculpture. Prosternum with faintly reticulate microsculpture. Pterothorax: Elytron ( Fig. 23 , e) without microsculpture; with 2 macrosetae, not set in punctures; laterally with 2 ridges (cf. Fig. 24 , ek). Mesothoracic epimeral region ( Fig. 24 , mer) shiny, without microsculpture. Metathoracic pleural region ( Fig. 24 , m) shiny, without microsculpture. Metathoracic pleural ridge present ( Fig. 24 , mp), fully developed; metathoracic pleural groove ( Fig. 24 , gr) incomplete posteriorly, forming elongate oval punctiform impression. Abdomen: Abdominal vestiture short, somewhat appressed, dorsally more or less evenly projecting posteriorly. Aedeagus ( Fig. 156 ): “ Type B” (see description on p. 8). Median lobe with apical part delimited ventrally from basal part ( Fig. 156 , arrow). Apical part of median lobe with sides distinctly narrowed at middle, forming rounded lateral lobes, produced into elongate, narrow point. Both apicolateral and apicomedial setae long ( Fig. 159 ). Shaft setae absent ( Fig. 159 , cf. Fig. 153 ). Paramere not exceeding apex of median lobe; slender in both dorsal and lateral view; in dorsal view with outer side more or less straight ( Fig. 159 ); with 4 setae at apex.

Etymology. The name minutus (-a, -um) is an adjective from Latin meaning small or minute, and refers to the small size of this species compared to congeners.

Distribution. ( Map 5 ). North Island: RI.

Remarks. Agnosthaetus minutus is most similar externally to A. akatarawa ( brouni species-group), from which it may be distinguished by the distinct microsculpturing of the head (anterior to the dorsal sulci), evenly semicircular eye (similar to Figs. 57–60 ), double elytral margin ( Fig. 24 , el, mr), and complete metathoracic pleural ridge ( Fig. 24 , mp). Despite their overall similarity, the aedeagal characters of A. minutus clearly ally it with the other species of the imitator species-group, within which it seems morphologically closest to A. stilbus in lacking shaft setae of the median lobe (otherwise uniformly present in Agnosthaetus ; Figs. 155 , 159 , cf. Fig. 153 , shs). The outwardly curving shape of the aedeagal parameres shown in Fig. 156 is an artifact of clearing in KOH; the illustration in Fig. 159 (of the second known specimen) accurately portrays the paramere structure.

Figures

Map 5. Geographic distribution of all georeferenced specimens of North Island species in the Agnosthaetus imitator species-group. Triangles = A. imitator; stars = A. aorangi; circles = A. lanceolatus; squares = A. stilbus; X = A. minutus.

Figs. 156–158. Aedeagi of species in the Agnosthaetus imitator species-group, dorsal (left) and right lateral (right) views. 156) A. minutus; 157) A. lanceolatus; 158) A. kaikoura. Scale bar = 100 mm.

Figs. 159–161. Apex of median lobe of species in the Agnosthaetus imitator species-group, ventral view.

Figs. 23–24. Agnosthaetus cariniceps, thorax. 23) Dorsal view; 24) Left lateral view. Scale bars = 100 mm.

Figs. 10–13. Head capsules of Agnosthaetus spp. 10) A. stilbus; 11) A. rodmani; 12) A. brouni; 13) A. chiasma. Scale bars = 100 mm.

Figs. 63–68. Heads of Agnosthaetus spp., ventral view. 63) A. brouni; 64) A. stilbus, oblique view; 65) A. chiasma;

Figs. 189–194. Mandibles of Agnosthaetus spp., dorsal view (189–193, left; 194, right). 189) A. newtoni; 190) A. falx; 191) A. stenomastax; 192) A. heteromastax (Rakeahua Valley); 193) A. heteromastax (Big South Cape Island); 194) A. heteromastax (Twilight Bay). Scale bar = 100 mm.

Figs. 75–78. Pronota of Agnosthaetus spp. 75) A. vicinus; 76) A. stilbus; 77) A. nitidus; 78) A. brouni. Scale bar =

Figs. 69–74. Pronota of Agnosthaetus spp. 69) A. chiasma; 70) A. rodmani; 71) A. heteromastax; 72) A. stenomastax;

Figs. 152–155. Apex of median lobe of species in the Agnosthaetus imitator species-group, ventral view.

Figs. 57–62. Heads of Agnosthaetus spp., dorsal view. 57) A. vicinus; 58) A. heteromastax; 59) A. nitidus;