Psammostiba Yosii & Sawada, 1976

Gusarov, Vladimir I., 2003, A revision of Nearctic species of the genera Adota Casey, 1910 and Psammostiba Yosii & Sawada, 1976 (Coleoptera: Staphylinidae: Aleocharinae), Zootaxa 185, pp. 1-35 : 20-24

Psammostiba Yosii & Sawada, 1976 , stat. nov.

( Figs. 53­88 )

Atheta (Panalota) : Brundin, 1943: 19, ex parte.

Atheta ( Psammostiba Yosii & Sawada, 1976 ): 82 (type species: Homalota hilleri Weise, 1877 , by original designation).

Diagnosis. Psammostiba can be distinguished from the other athetine genera by the combination of the following characters: body parallel­sided; anterior margin of labrum concave; antennal articles 5­10 slightly elongate or subquadrate ( Fig. 64 ); ligula long and split in apical half ( Fig. 58 ); labial palpus with setae and present ( Fig. 58 ); pronotum slightly transverse, 1.1 times as wide as long, with microsetae directed anteriorly along the midline; in lateral portions of the disc microsetae directed laterally (Type I, Benick & Lohse 1974) ( Fig. 62 ); pronotal macrosetae short; pronotal hypomera fully visible in lateral view; medial macroseta of mesotibia inconspicuous and thin, as long as tibial width; tarsal formula 4­5­5; metatarsal segment 1 as long as segment 2 ( Fig. 65 ); no empodial setae (best observed in lateral view; Fig. 65 ); tarsal claws of different length (best observed in dorsal view; Fig. 66 ), external claw longer than internal; copulatory piece without pointed apex ( Figs. 67­68 ); proximal portion of spermatheca with one coil ( Figs. 77 , 87 ).

Psammostiba can be distinguished from Atheta by strong isodiametric microsculpture of the entire body; by the concave anterior margin of the labrum; by basal impression on the tergum 6; by lacking empodial seta and by tarsal claws of different length.

Psammostiba differs from Adota in having antennal article 3 longer than article 2 ( Fig. 64 ); larger body; tarsal claws of different length; and in lacking the empodial seta. Description. Length 3.0­5.0 mm, pronotal width 0.59­0.89 mm. Body black with brown legs and light brown tarsi.

Head 1.1 times as wide as long; eyes large, temple length to eye length ratio 0.9­1.1; infraorbital carina incomplete, reaching middle of eye or very short. Antennal article 3 slightly longer than article 2, articles 4­10 slightly elongate or subquadrate, terminal article without coeloconic sensilla, shorter or as long as articles 9 and 10 combined ( Fig. 64 ). Labrum ( Fig. 58 ) transverse, with concave anterior margin. Adoral surface of labrum (epipharynx) as in Fig. 54 . Mandibles ( Figs. 55­57 ) broad, right mandible with a small medial tooth; dorsal molar area with velvety patch consisting of very small denticles (invisible at 400x). Maxilla ( Fig. 60 ) with galea projecting slightly beyond apex of lacinia; apical lobe of galea covered with numerous fine and short setae; internal margin of galea with long subapical setae; apical 1/3 of lacinia with row of closely spaced spines, middle portion produced medially and covered with numerous setae ( Fig. 60 ). Labium as in Figs. 58­59, 61 ; ligula long and split in apical half; medial area of prementum with 2 pores and with 18­30 pseudopores, lateral areas each with two asetose pores, single setose pore and 18­33 pseudopores ( Fig. 58 ). Hypopharyngeal lobes as in Fig. 59 . Labial palpus with setae and present ( Fig. 58 ). Mentum ( Fig. 61 ) with concave anterior margin.

Pronotum slightly transverse, 1.2 times as wide as long, with microsetae directed anteriorly in midline; in lateral portions of disc microsetae directed laterally (Type I, Benick & Lohse 1974) ( Fig. 62 ); macrosetae short; hypomera fully visible in lateral view. Meso­ and metasternum as in Fig. 63 , mesosternal process narrow, extending about 4/7 length of mesocoxal cavities, metasternal process short, mesosternum and mesosternal process not carinate medially; relative lengths of mesosternal process: isthmus: metasternal process in ratio of about 4:1:2; mesocoxal cavities margined posteriorly; mesocoxae narrowly separated. Medial macroseta of mesotibia inconspicuous, shorter than tibial width. Tarsal segmentation 4­5­5, metatarsal segment 1 as long as segment 2 ( Fig. 65 ). No empodial setae (best observed in lateral view; Fig. 65 ); tarsal claws of different length (best observed in dorsal view; Fig. 66 ), external claw longer than internal. Posterior margin of elytra straight. Wings fully developed.

Abdominal terga 3­6 with moderate basal impression. Tergum 7 as long as tergum 6. Punctation on terga 6­7 almost as dense as on terga 3­5. Tergum 7 with wide white palisade fringe.

Internal sac of aedeagus with a medial pair of partially sclerotized structures ( Figs. 67­ 68 ; SS) which may be homologous to medial lamellae present in many genera of Athetini. Copulatory piece without pointed apex ( Figs. 67­68 ); proximal portion of spermatheca with a single coil ( Figs. 77 , 87 ).

Type species. Homalota hilleri Weise, 1877 , by original designation.

Discussion. Although originally proposed as a subgenus of Atheta , Psammostiba differs from Atheta in many characters (see Diagnosis) and it is considered here as a distinct genus of the tribe Athetini.

Yosii & Sawada (1976) state that in P. hilleri and P. jessoensis the "claws of all legs are variable in length and strength". In all twenty specimens of P. jessoensis examined by me the external claws were significantly longer than the internal ones.

Psammostiba seems to be restricted to the coasts of the Northern Pacific. Psammostiba comparabilis (Mäklin in Mannerheim, 1853) and P. kenaii Gusarov , sp. n. are the only known Nearctic species of this genus. Psammostiba includes three additional Palaearctic species distributed in the Far East: P. hilleri ( Weise, 1877) , P. jessoensis ( Brundin, 1943) and P. kamtschatica ( Brundin, 1943) .

Figures

FIGURES 53 ­ 57. Mouthparts of Psammostiba jessoensis (Brundin) (male from Rudnaya Pristan', Russia). 53 – labrum; 54 – epipharynx; 55 – left mandible, dorsal view; 56 – left mandible, ventral view; 57 – right mandible, dorsal view. Scale bar 0.2 mm.

FIGURES 58 ­ 61. Mouthparts of Psammostiba jessoensis (Brundin) (male from Rudnaya Pristan', Russia). 58 – prementum; 59 – hypopharynx; 60 – right maxilla, ventral view; 61 – mentum. Scale bar 0.1 mm (58 ­ 59, 61), 0.2 mm (60).

FIGURES 62 ­ 64. Details of Psammostiba jessoensis (Brundin) (62 ­ 63; female from Rudnaya Pristan', Russia) and P. comparabilis (Mäklin) (64; male from Homer, Alaska). 62 – pronotum; 63 – meso­ and metathorax, ventral view; 64 – right antenna. Scale bar 0.4 mm.

FIGURES 65 ­ 68. Details of Psammostiba jessoensis (Brundin) (65, 67; males from Rudnaya Pristan', Russia) and P. comparabilis (Mäklin) (66, 68; males from Homer, Alaska). 65 – right metatarsus; 66 – left metatarsal segment 5 and metapretarsus, dorsal view; 67 ­ 68 – everted internal sac, parameral view. SS – medial pair of sclerotized structures. Scale bar 0.2 mm.

FIGURES 73 ­ 77. Genitalia of Psammostiba comparabilis (Mäklin) (male (73 ­ 76) and female (77) from Homer, Alaska). 73 – median lobe, parameral view; 74 – apex of median lobe, parameral view; 75 – median lobe, lateral view; 76 – apex of median lobe, lateral view; 77 – spermatheca. Scale bar 0.1 mm (74, 76), 0.2 mm (73, 75, 77).

FIGURES 78 ­ 81. Abdominal segment 8 of Psammostiba kenaii Gusarov, sp. n. (holotype, male (78 ­ 79), and paratype, female (80 ­ 81), from Haines, Alaska). 78 – male tergum 8; 79 – male sternum 8; 80 – female tergum 8; 81 – female sternum 8. Scale bar 0.2 mm.

FIGURES 82 ­ 87. Genitalia of Psammostiba kenaii Gusarov, sp. n. (holotype, male (82 ­ 86), and paratype, female (87), from Haines, Alaska). 82 – median lobe, parameral view; 83 – apex of median lobe, parameral view; 84 – median lobe, lateral view; 85 – apex of median lobe, lateral view; 86 – apex of left paramere; 87 – spermatheca. Scale bar 0.1 mm (83, 85 ­ 86), 0.2 mm (82, 84, 87).

FIGURE 88. Geographical distribution of Nearctic species of Psammostiba. Records of P. kenaii Gusarov, sp. n. from British Columbia and California are based on female specimens only.