Micronialoe Park, Kwon & Lafer, 1996

Kim, Dooyoung & Suh, Sang Jae, 2024, Review of the ground beetle subgenus Micronialoe from Korea, with a description of a new species (Coleoptera: Carabidae: Pterostichus), Zootaxa 5471 (4), pp. 451-464 : 453-454

Subgenus Micronialoe Park, Kwon & Lafer, 1996

Micronialoe Park, Kwon & Lafer, 1996: 73 . Type species: Pterostichus (Micronialoe) bifoveolatus Park, Kwon & Lafer, 1996 .

Diagnosis. Small-sized (6–9 mm in length); head small (relative to pronotum and elytra), eye small to medium-sized ( Figs 2C , 3B , 7C , 8C ), tempus moderately to well developed, anterior margin of labrum faintly or slightly rounded, anterior margin of clypeus linear, submentum with four setae ( Fig. 3A ), penultimate labial palpomere with two setae on inner margin and one very short additional seta near apex on outer margin, apex of antennomere 2 with one seta; pronotum with one or two pairs of basal foveae; elytra with distinct humeral tooth, parascutellar pore absent, parascutellar striole short or absent, interval 3 without setigerous pores, marginal umbilicate series with medial pore, well-delimited from humeral and apical groups; hindwing reduced to tiny scale; prosternal process border absent, propleura coarsely punctate; metacoxa with two setae, metatrochanter with one seta, metafemur with two long setae, tarsomere 5 glabrous ventrally; right paramere curved at apex ( Figs 5G , 7K , 8J ).

The significant character of this subgenus is the lack of setigerous pores on the elytral interval 3, which is a rare characteristic within the genus Pterostichus ( Morita 1992; Sciaky 1997). The following subgenera are known to possess this characteristic: Abea Morita , Carllindrothius Habu , Licentius Jedlicka , Megabea Sciaky, and Qianius Jia, He & Tian. The closest subgenus of Micronialoe is believed to be Abea , which prominently differs only in the shape of the right paramere: short and linear in Abea , whereas elongated and bent in Micronialoe ( Morita 1992, 2005). Carllindrothius , Licentius , and Megabea are also similar but differ from Micronialoe in not having a medial group of setae along the marginal umbilicate series ( Habu 1955; Jia et al. 2021, Shi, personal communication). Qianius differs from Micronialoe in having two setae on the submentum and a parascutellar pore on the elytra ( Jia et al. 2021). Besides, part of the species in Orientostichus Sciaky & Allegro , Pseudethira Sciaky , and Steropanus Fairmaire are also known to lack setigerous pores on the elytral interval 3 (Schmidt 2012; Fedorenko 2018, 2023). Orientostichus and Steropanus differ from Micronialoe in having an asetose metatrochanter and a submentum with two setae ( Fedorenko 2023), and Pseudethira in having an asetose metatrochanter and long terminal lamella of the median lobe ( Sciaky 1996; Shi et al. 2013).

Redescription. Body length: 6–9 mm.

Coloration black or brownish-black and shiny.

Head small, convex, glabrous; microsculpture consisting of isodiametric meshes and sparse fine punctures dorsally ( Fig. 4A ); eye small to medium-sized, weakly to moderately convex; tempus moderately to well developed; mandible narrowly rounded at apex; anterior margin of labrum faintly or slightly rounded; anterior margin of clypeus linear; frontal impression moderately curved toward anterior supraorbital pore; supraorbital groove deep, extending toward the level of posterior supraorbital pore; anterior supraorbital pore located behind the level of anterior margin of eye, posterior supraorbital pore located behind the level of posterior margin of eye; mentum and submentum separated by transverse suture, tooth of mentum bifid, submentum with four setae; ligula wide, apex truncate, faintly emarginate, with two apical setae; paraglossa slender, narrowly rounded at apex, separated from ligula by notch; penultimate labial palpomere with two setae on inner margin and one very short additional seta near apex on outer margin; antennae extending behind basal margin of elytra, antennomere 2 with one seta, antennomeres 1–3 glabrous.

Pronotum moderately convex anteriorly, somewhat flat posteriorly, wider than long; microsculpture consisting of fine transverse meshes and sparse fine punctures ( Fig. 4B ); apical margin emarginate, bordered laterally; apical angle narrowly rounded, slightly to distinctly protruded anteriorly; lateral margin with or without sinuation before basal angle, distinctly bordered, with two setae; anterolateral seta near widest point and posterolateral seta near basal angle; base bordered laterally, faintly bisinuate, slightly wider than apical width; disk glabrous; median line distinct; anterior transverse impression faint or absent; posterior transverse impression more or less distinct; with one or two pairs of basal foveae.

Elytra moderately convex, somewhat mat on disk; microsculpture consisting of fine transverse meshes and sparse fine punctures ( Fig. 4C ); basal edge moderately curved, reaching stria 1 medially; humeral angle obtuse; humerus forming distinct thick tooth; apical sinuation very weak; parascutellar pore absent; parascutellar striole short or absent; intervals rather convex laterally, interval 3 without setigerous pores; striae deep, punctate from base to near basal half; marginal umbilicate series composed of three groups, humeral group with usually 5 pores, medial group with 1 pore, and apical group with 7–9 pores. Hindwing reduced to a tiny scale.

Ventral side convex; pro- and metasternum, and sternites smooth medially; propleura, meso- and metepisternum, mesosternum, and lateral areas of pro- and metasternum distinctly and densely punctate; prosternal process border absent; metepisternum short, anterior margin as long as outer margin; sides of sternites except sternite VII rugosopunctate; posteromedian area of sternite VII of male with or without modification; apical margin of sternite VII widely rounded in both sexes, with a pair of setae in male and two pairs in female before apical margin.

Legs. Metacoxa with two setae; metatrochanter with one seta; metafemur with two setae; tarsomere 5 glabrous ventrally.

Male genitalia. Median lobe of aedeagus stout to moderately slender; apical orifice placed on dorsal side or bent to left; internal sac with sclerotized areas; left paramere wide, with transverse apophysis basally; right paramere slender, slightly to distinctly curved; sternite IX widely rounded.

Distribution. The species are only known from the southern part of Korea and Tsushima Island, Japan.

Ecology. Members of Micronialoe are infrequently collected, but are typically found beneath rocks or stacked leaves in small to medium-sized humid valleys and ravines ( Fig. 1 ). They are occasionally found at the bottom of the drainage channels along the forest roads.

Figures

FIGURE 1. Habitat of Pterostichus (Micronialoe) spinulosus sp. nov. in Mt. Biseulsan, Daegu, South Korea.

FIGURE 2. Pterostichus (Micronialoe) spinulosus sp. nov., male. (A) habitus, dorsal view; (B) ditto, ventral view; C head and pronotum, dorsal view. Scale bars: 1 mm.

FIGURE 3. Pterostichus (Micronialoe) spinulosus sp. nov., male. (A) mouthpart, ventral view; (B) ditto, lateral view; (C) metepisternum; (D) sternite VII. Scale bars: 0.3 mm.

FIGURE 4. Microsculpture of Pterostichus (Micronialoe) spinulosus sp. nov. (A) head; (B) pronotum; (C) elytron. Scale bars: 0.1 mm.

FIGURE 5. Male and female genitalia of Pterostichus (Micronialoe) spinulosus sp. nov., male A–H, female (I). (A) median lobe of aedeagus, right lateral view; (B) ditto, dorsolateral view; (C) ditto, dorsal view; (D) ditto, ventral view; (E) ditto, left lateral view; (F) left paramere; (G) right paramere; (H) male sternite IX; (I) female genitalia (laterotergite, basal stylomere, and apical stylomere), ventral view. Scale bars: 0.3 mm A–E, H; 0.2 mm F, G, 0.1 mm I. Abbreviations: SP: spiny patch; VS: ventral sclerite; CS: C-shaped sclerite; C: ventral carina.

FIGURE 7. Male habitus and genitalia of Pterostichus (Micronialoe) bifoveolatus Park, Kwon & Lafer. (A) habitus, dorsal view; (B) habitus, ventral view; (C) head and pronotum, dorsal view; (D) sternite VII; (E) median lobe of aedeagus, right lateral view; (F) median lobe of aedeagus, dorsolateral view; (G) median lobe of aedeagus, dorsal view; (H) median lobe of aedeagus, ventral view; (I) median lobe of aedeagus, left lateral view; (J) left paramere; (K) right paramere. Scale bars: 1 mm A–C; 0.5 mm D; 0.3 mm E–I; 0.2 mm J–K. Abbreviations: VS: ventral sclerite; CS: C-shaped sclerite; C: ventral carina.

FIGURE 8. Male habitus and genitalia of Pterostichus (Micronialoe) chogyesanus Park, Kwon & Lafer. (A) habitus, dorsal view; (B) habitus, ventral view; (C) head and pronotum, dorsal view; (D) sternite VII; (E) median lobe of aedeagus, right lateral view; (F) median lobe of aedeagus, dorsal view; (G) median lobe of aedeagus, ventral view; (H) median lobe of aedeagus, left lateral view; (I) left paramere; (J) right paramere. Scale bars: 1 mm A–C; 0.5 mm D; 0.3 mm E–H; 0.2 mm I–J. Abbreviation: CS: C-shaped sclerite.