Microlia Casey, 1910

Gusarov, Vladimir I., 2002, A revision of the genus Microlia Casey, 1910 (Coleoptera: Staphylinidae: Aleocharinae: Hoplandriini), Zootaxa 34, pp. 1-24 : 2-7

Microlia Casey, 1910 ( Figs. 1­80 )

Dolosota ( Microlia Casey, 1910 ): 144 (subtribe Athetina Casey, 1910 ).

Nosora Casey, 1911: 145 (tribe Myrmedoniini Thomson, 1867 ), syn. nov.

Nosora: Leng, 1920: 122 (as valid genus; tribe Myrmedoniini ).

Pancota (Microlia) : Leng, 1920: 122 (as valid subgenus; tribe Myrmedoniini ).

Atheta (Microlia) : Fenyes, 1920: 202 (as a synonym of Atheta ( Pancota )).

Nosora: Fenyes, 1920: 308 (as valid genus; tribe Hoplandriini Casey, 1910 ).

Atheta (Microlia) : Bernhauer & Scheerpeltz, 1926: 660 (as a synonym of Atheta ( Pancota )).

Nosora: Bernhauer & Scheerpeltz, 1926: 717 (as valid genus; subtribe Hoplandriina ).

Nosora: Leng & Mutchler, 1927: 23 (as valid genus).

Nosora: Blackwelder, 1952: 262 (as valid genus).

Ischnopoda (Microlia) : Blackwelder, 1952: 202, 246, 288 (as a synonym of Ischnopoda ( Pancota )).

Atheta (Microlia) : Moore & Legner, 1975: 351 (as a synonym of Atheta ( Pancota )).

Nosora: Moore & Legner, 1975: 456 (as valid genus).

Acrotona (Microlia) : Seevers, 1978: 100 (as valid subgenus; tribe Athetini ).

Nosora: Seevers, 1978: 142 (as valid genus; tribe Hoplandriini ).

Nosora: Ashe in Newton et al., 2000: 360 (as valid genus; tribe Hoplandriini ).

Acrotona (Microlia) : Ashe in Newton et al., 2000: 368 (as valid subgenus; tribe Athetini ).

Nosora: Hanley, 2001: 221 (as valid genus; tribe Hoplandriini ).

Diagnosis. Microlia can be distinguished from other aleocharine genera by the combination of the following characters: body broadest at elytra; antennal articles 5­10 strongly transverse ( Figs. 12, 30 , 48 ); labial and maxillary palpi with pseudosegment ( Figs. 6, 9); apical half of ligula divided into two lobes ( Figs. 9); pronotum with microsetae directed posteriorly along the midline of the disc (Type V, Benick & Lohse 1974) ( Fig. 13); pronotal macrosetae short; pronotal hypomera invisible in lateral view; medial microseta of mesotibia inconspicuous, shorter than tibial width; tarsal formula 4­4­5 or 4­5­5; metatarsal segment 1 not longer than segment 2; one empodial setae; posterior margin of male abdominal sternum 8 extended posteriorly as large triangular lobe ( Figs. 21 , 34 , 62 ); median lobe of aedeagus with long and narrow apical process ( Figs. 26­29 , 68­72 ); parameres with two long and two short macrosetae ( Figs. 31 , 44 ); spermatheca forming two to many coils ( Figs. 32­33 , 47 ) or numerous irregular loops ( Figs. 42­43 ).

Description. Length 1.8­2.3 mm. Body from brownish yellow to brown with darker apex of antennae and abdominal segments 4­6, in some species with darker elytra or head; elytra much broader than pronotum and abdomen.

Head transverse; eyes large, 2­3 times as long as temples; infraorbital carina complete. Antennal article 2 longer than article 3, 4 subquadrate or transverse, 5­10 transverse or strongly transverse (ratio 2.0­2.4), apical article with two coeloconic sensilla ( Figs. 12, 30 , 48 ). Labrum ( Fig. 1 ) transverse, anterior margin with four shallow emarginations. Adoral surface of labrum (epipharynx) without transverse row of pores ( Fig. 2 ). Mandibles ( Figs. 3­5 ) broad, right mandible with a small medial tooth; dorsal molar area with velvety patch consisting of tiny denticles (visible at x400; Fig. 3 ). Maxilla ( Figs. 6­8) with galea extending beyond apex of lacinia; apical lobe of galea covered with numerous fine and short setae; apical half of lacinia with row of closely spaced spines, middle portion produced medially and covered with numerous setae. Maxillary palpus with four segments and pseudosegment ( Fig. 6). Labium as in Figs. 9­11; labial palpi with three segments and pseudosegment ( Fig. 9); apical half of ligula divided into two lobes; medial area of prementum without pores or pseudopores, lateral areas with 4­6 pores and single spinose pore. Hypopharyngeal lobes as in Fig. 10. Mentum ( Fig. 11) with protruding anterior angles, straight anterior margin, medial area without pores.

Pronotum ( Fig. 13) strongly transverse, broadest near middle, sides broadly rounded; anterior margin straight, posterior margin convex; surface covered with microsetae directed posteriorly in midline, laterally and obliquely posteriorly in lateral areas (Type V, Benick & Lohse 1974); macrosetae short; hypomera invisible in lateral view. Meso ­ metasternum as in Fig. 14, mesosternal process long and wide, extended about 1/2 length of mesocoxal cavities, metasternal process almost non­existent, anterior margin of metasternum only slightly convex medially; mesosternum and mesosternal process not carinate medially; relative lengths of mesosternal process: isthmus: metasternal process in ratio of about 11:10:2; mesocoxal cavities margined posteriorly; mesocoxae contiguous. Medial microseta of mesotibia inconspicuous, shorter than tibial width. Tarsal segmentation 4­5­ 5 or 4­4­5 ( Figs. 15­20); metatarsal segment 1 not longer than segment 2. One short empodial seta. Wings fully developed. Posterior margin of elytra slightly concave near postero­lateral angle.

Abdominal terga 3­5 with moderately transverse basal impressions. Tergum 7 1.4­1.6 times longer than tergum 6. Puncturation on terga 6­7 not significantly sparser than on terga 3­5. Tergum 7 with wide white palisade fringe.

Male secondary characters include some of the following: lateral triangular lobes or medial knob at posterior margin of tergum 3, longitudinal tubercles on terga 7 and 8, crenulation of posterior margin of tergum 8. Posterior margin of male abdominal sternum 8 extended posteriorly as pointed triangular lobe ( Figs. 21 , 34 , 62 ). Median lobe of aedeagus with long and narrow apical process ( Figs. 26­29 , 68­72 ). Parameres with two long and two short macrosetae ( Figs. 31 , 44 ). Copulatory piece of internal sac with long apical process ( Fig. 57 ). Spermatheca forming two to many coils ( Figs. 32­33 , 47 ) or numerous irregular loops ( Figs. 42­43 ).

Type species. Dolosota pernix Casey, 1910 , by original designation.

Synonyms. Nosora azteca Casey, 1911 , the type species of the genus Nosora by original designation is similar to M. pernix in all characters listed in the Diagnosis. Therefore Nosora is placed in synynymy with Microlia .

Discussion. My examination of the lectotype of Microlia meticola ( Casey, 1911) (original combination: Nosora meticola ) revealed that in this species the tarsal formula is 4­4­5 ( Fig. 15). Examination of additional material demonstrated that in M. meticola both sexes have this tarsal formula and there is no intraspecific variation in this character (in total more than 80 specimens were examined). Up to now this fact has been overlooked (despite the type of N. meticola carrying a small label “4­4­5”, apparently by Casey), and all authors who wrote about the group believed the formula was 4­5­5. One of the new species of Microlia described below ( M. tetramera ) also has mesotarsus with four articles ( Figs. 17­18).

Traditionally in the aleocharine taxonomy the tarsal formula was considered an important character, often stable at the level of tribe. However in a few groups the tarsal formula was found to vary within the genus (as in Gyronycha Casey, 1893 (Seevers 1978)) . The genus Microlia is a new example of such intrageneric variation in tarsal formula.

To establish homologies of tarsal segments between the species with different tarsal formulas the setation was examined. In 4­5­5 species every segment of mesotarsus carries a pair of lateral setae ( Figs. 19­20, l); on ventral side the first segment has two pairs of setae, second­fourth have one pair of ventral setae each, fifth has no ventral setae ( Fig. 20, v); on dorsal side the first segment has no setae, second­fourth segments have one or two dorsal setae each, fifth has two pairs of dorsal setae ( Figs. 19, d). Comparison between the 4­5­5 ( Figs. 19­20) and 4­4­5 ( Fig. 17­18) species shows that in the 4­4­5 species the last segment of mesotarsus has the setae found on both fourth and fifth segments of the 4­5­5 species: a pair of ventral setae ( Fig. 18, v), 1+1+2 dorsal setae ( Fig. 17, d) and two pairs of lateral setae ( Figs. 17­18, l). Apparently the last segment of mesotarsus in the 4­4­5 species is homologous to the two last segments of mesotarsus in the 4­5­5 species.

The key for aleocharine genera by Ashe (Newton et al. 2000) does not allow to identify the species of Microlia (= Nosora ) with tarsal formula 4­4­5. These species run to couplet 24 in Key E. To incorporate Microlia the key should be modified by inserting additional couplet as follows (p. 308 in Newton et al. 2000):

24(22) Maxillary (Fig. 155.22, arrow) and labial (Fig. 159.22) palpi with apical pseudo­

segment, appearing to have 5 and 4 palpomeres, respectively........ Microlia . – Maxillary and labial palpi without apical pseudosegments............... 24a 24a(24) Body distinctly … (from here follow the original key)

The 4­5­5 species of Microlia reach Nosora at couplet 3 in Key C by Ashe (Newton et al. 2000).

Two species were originally included in subgenus Microlia by Casey (1910). The second species, Dolosota (M.) petulans Casey, 1910 belongs to the genus Acrotona Thomson, 1859 , tribe Athetini .

All species of Microlia mentioned in this paper are similar in external characters including proportions of antennal segments. The species represented in my material by many specimens show considerable variation in body coloration and sometimes in puncturation of pronotum. Some species are known from only few specimens which does not allow to assess variability of body coloration. Considering the observed intraspecific variation and the possibility that undescribed species of Microlia exist in Central America, it seems reasonable that a key to known species based on coloration of specimens will be of limited value. That is why the key below is based mostly on the characters of genitalia and secondary sexual characters even though some species are known by one sex only.

There can be little doubt that many undescribed species of Microlia exist in Central and possibly South America. The high diversity of Microlia in Central America is illustrated by the fact that in a single locality in Costa Rica three species of Microlia were found ( M. pentamera Gusarov , sp. nov., M. tetramera Gusarov , sp. nov. and an additional species represented by females only; see Discussion after the description of M. tetramera ).

Figures

FIGURES 1 ­ 5. Mouthparts of Microlia meticola (Casey) (Arizona). 1 – labrum; 2 – epipharynx; 3 – left mandible, dorsal view; 4 – left mandible, ventral view; 5 – right mandible, dorsal view. Scale bar 0.1 mm.

FIGURES 26 ­ 33. Details of Microlia silacea (Erichson) (26 ­ 29, 31 – paralectotype of Homalota silacea; 30, 33 – North Carolina; 32 – lectotype of Homalota silacea). 26 – median lobe of aedeagus, lateral view; 27 – apex of median lobe of aedeagus, lateral view; 28 – median lobe of aedeagus, ventral view; 29 – apex of median lobe of aedeagus, ventral view; 30 – antenna; 31 – apical lobe of right paramere, internal view; 32 ­ 33 – spermatheca. Scale bar 0.2 mm (25, 27, 29, 31 ­ 33), 0.1 mm (26, 28, 30).

FIGURES 45 ­ 48. Details of Microlia azteca (Casey) (paralectotype). 45 – female sternum 8; 46 – female tergum 8; 47 – spermatheca; 48 – right antenna. Scale bar 0.2 mm.

FIGURES 21 ­ 25. Abdominal segment 8 and female accessory sclerites of Microlia silacea (Erichson) (21 – paralectotype of Homalota silacea; 22, 25 – North Carolina; 23 ­ 24 – lectotype of Homalota silacea). 21 – male sternum 8; 22 – male tergum 8; 23 – female sternum 8; 24 – female tergum 8; 25 – female accessory sclerites. Scale bar 0.25 mm (21 ­ 24), 0.1 mm (25).

FIGURES 34 ­ 37. Details of Microlia meticola (Casey) (Arizona). 34 – male sternum 8; 35 – male tergum 8; 36 – female sternum 8; 37 – female tergum 8. Scale bar 0.4 mm.

FIGURES 62 ­ 67. Details of Microlia tetramera Gusarov, sp. nov. (62 ­ 63 – holotype; 64 ­ 67 – possible female of M. tetramera from Costa Rica, 64 ­ 65 – type A, 66 ­ 67 – type B). 62 – male sternum 8; 63 – male tergum 8; 64, 66 – female sternum 8; 65, 67 – female tergum 8. Scale bar 0.2 mm.

FIGURES 68 ­ 76. Details of Microlia tetramera Gusarov, sp. nov. (68 ­ 72, 75 ­ 76 – holotype; 73 ­ 74 – possible female of M. tetramera from Costa Rica). 68 – median lobe of aedeagus, lateral view; 69 – apex of median lobe of aedeagus, lateral view; 70 – median lobe of aedeagus, ventral view; 71 – apex of median lobe of aedeagus, ventral view; 72 – apex of median lobe of aedeagus, apical ventral view; 73 ­ 74 – spermatheca; 75 – apical lobe of right paramere, internal view; 76 – abdominal segment 3, dorsal view. Scale bar 0.2 mm (68, 70, 73 ­ 74), 0.1 mm (69, 71 ­ 72, 75), 0.55 mm (76).

FIGURES 38 ­ 44. Details of Microlia meticola (Casey) (Arizona). 38 – median lobe of aedeagus, lateral view; 39 – apex of median lobe of aedeagus, lateral view; 40 – median lobe of aedeagus, ventral view; 41 – apex of median lobe of aedeagus, ventral view; 42 ­ 43 – spermatheca; 44 – apical lobe of right paramere, internal view. Scale bar 0.2 mm (38, 40, 42 ­ 43), 0.1 mm (39, 41, 44).

FIGURES 53 ­ 61. Details of Microlia pentamera Gusarov, sp. nov. (53 ­ 58, 61 – holotype; 59 ­ 60 – paratypes). 53 – median lobe of aedeagus, lateral view; 54 – apex of median lobe of aedeagus, lateral view; 55 – median lobe of aedeagus, ventral view; 56 – apex of median lobe of aedeagus, ventral view; 57 – copulatory piece of internal sac; 58 – apical lobe of right paramere, internal view; 59 ­ 60 – spermatheca; 61 – abdominal segment 3, dorsal view. Scale bar 0.2 mm (53, 55, 59 ­ 60), 0.1 mm (54, 56 ­ 58), 0.55 mm (61).