Semiardistomis Kult, 1950

Valdes, Pavel, 2012, Notes about morphological features of the Western Hemisphere subtribe Ardistomina, and revision of genus Semiardistomis Kult (Coleoptera, Carabidae, Scaritinae, Clivinini), ZooKeys 210, pp. 19-67 : 22-29

publication ID	https://dx.doi.org/10.3897/zookeys.210.3042
publication LSID	lsid:zoobank.org:pub:DF32BC38-E839-4DC4-8EA0-FB6508EC7B2B
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scientific name	Semiardistomis Kult, 1950
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Genus Semiardistomis Kult, 1950

Ardistomis (Semiardistomis) Kult, 1950: 301. Type species: Clivina labialis Chaudoir, 1837, designated by Kult (1950: 301).

Ardistomis (Ardistomiellus) Kult, 1950: 303. Type Species: Ardistomis viridis Say, 1823, designated by Kult (1950: 303). Synonymy established by Whitehead [in Reichardt] (1977: 392).

Semiardistomis Kult. Nichols (1988b: 98); Ball and Bousquet (2001: 45, 74); Bousquet (2006: 10); Valdés (2007: 24); Erwin (2011: 233).

Diagnostic combination.

Features of adults used in recognition of this genus include: antennomere 2 shorter than antennomere 3 ( Fig. 1 View Figures 1–2 , a2, a3); glossal sclerite of ligula ( Figs 13B, 14B View Figures 13–21 ) with a secondary pair of setae; mentum with median carina ( Figs 13C, 14C View Figures 13–21 ) extended distal in form of an appendiform keel; protibia ( Figs 23, 24 View Figures 22–24 ) with basal half of ventral surface with a group of setae.

Description.

Adult. Body shape, color and size ( Figs 1, 2 View Figures 1–2 , 37 View Figures 37–38 - 41 View Figures 39–40 , 44 View Figures 45–46 - 52 View Figures 51–52 ): Body pedunculate. Body size small, ranging from 4.0 to 7.5 mm. Body monochromous, dark with metallic greenish and/ or brassy luster, shiny in species without microsculpture; appendages reddish brown. One species, Semiardistomis laevistriatus (Fleutiaux & Sallé), is dark brown a color also found in monticolous brachypterous species of the genus Ardistomis .

Microsculpture: Frontoclypeus mostly smooth; supraantennal lobes smooth; vertex with mesh pattern isodiametric; gena with mesh pattern isodiametric; gula with mesh pattern transverse. Mandibles smooth; submentum and mentum with mesh pattern isodiametric. Pronotal disc generally smooth or with mesh pattern isodiametric, microlines very shallow, marginally and smooth at the center; proepisternum smooth or with isodiametric mesh pattern, submarginal band of microsculpture absent; prosternum smooth or with mesh pattern transverse. Metasternum smooth or with mesh pattern transverse. Abdominal sterna smooth or with mesh pattern transverse. Elytra smooth or with isodiametric mesh pattern covering entirely or only part of the disc.

Chaetotaxy: Two pair of supraorbital setae (except for Semiardistomis puncticollis ); pronotal disc with two pair of marginal setae (except for Semiardistomis puncticollis and Semiardistomis viridis ); except for hirsute species, setae on elytral disc located in interval 3 and Semiardistomis darlingtoni (Kult) also in interval 5; abdominal sterna IV-VII with accessory setae.

Head capsule: Clypeus with anterior margin concave medially; lateral lobes distinct, projected at the same level or below anterior margin. Antennal lobes prominent, sometimes partially sulcate medially in basal half. Frontoclypeus smooth except in Semiardistomis rugosus (Putzeys). Frontal impressions deep and wide from base of antennal lobes to anterior margin of clypeus. Gena with sides subparallel. Eyes: Hemispherical, prominent. Antennae ( Figs 1, 2 View Figures 1–2 ): Filiform to submoniliform. Antennomere 1 (a1) with single preapical seta. Antennomere 2 (a2) with few setae, shorter than antennomere 3 (a3). Antennomeres 4-11 densely setose, setae short.

Mouthparts: Labrum ( Figs 3, 4 View Figures 3–5 ): anterior margin angulate, dentiform medially (dp); dorsal setae (ds) 7, as for most Clivinini ; apical portion of epipharyngeal setae (es) serrulate anteriolaterally. Maxillae ( Fig. 5 View Figures 6–12 ) with lacinia (lac) apical tooth sharp and curved; galeomere 1 (g1) slender, a little longer than galeomere 2 (g2), the latter flat, broad and sinuate in outline; palpomere 2 (mp2) thick and triangular in outline; palpomere 3 (mp3) subequal in length to palpomere 4 (mp4); palpomere 4 apically acuminate. Stipes (st) with 4 setae, palpifer (pf) with one seta. (This structure shows little difference from other clivinines being most similar to that of Ardistomis . Mandibles ( Figs 6A-6D View Figures 6–12 ): elongate, about 1.9 times longer than wide; ventral groove (vg) moderate in length, with short microtrichia (mt); left mandible with terebral ridge curved, the terebral tooth (tt) blunt and moderate in size, visible from ventral view, retinaculum (rt) broad, premolar tooth (pm) absent, the molar tooth (m) broad and rounded; right mandible with terebral ridge more or less straight, the terebral tooth small, not visible from ventral view, the retinaculum with acute anterior tooth, premolar tooth absent, and the molar tooth broad and rounded. Labium ( Figs 13A-C, 14A-C View Figures 13–21 ) with mental-submental suture complete; submentum with paramedian projections distinct, two pair of setae; mentum (m) trapezoidal, about 1.5 times wider than long; two pair of setae; lateral lobes with anterior margins angulate; mental tooth (mt) with distal margin almost straight, about 1/3 length of lateral lobes (ll); median carina (mc)(13C, 14C) extended distad, or not, beyond anterior margin of lateral lobes; pit organs (po) distinct, opened through oval orifices in basal part of mentum or on mental-submental suture; palpomere 3 (lp3) subequal in length to palpomere 2, palpomere 2 (lp2) bisetose; ligula ( Figs 13B, 14B View Figures 13–21 ) with glossal sclerite (gs) notably wide, its anterior margin with acuminate median projection and two long setae (as), two additional small setae (pas) located preapically; paraglossae (pg) divergent from glossal sclerite and covered with microtrichia dorsally, lobes thin and acuminate, extended distally beyond distal margin of glossal sclerite, apices serrulate.

Pronotum. Ovate or cordate, anterior transverse and median longitudinal impressions distinct, proepisternum visible from above, lateral border not extended to base in some specimens. Anterior transverse and median longitudinal impressions distinct. Proepipleura visible from above.

Elytra. Oval, convex; striae complete or obliterated to various degrees or absent (stria 1 always complete), punctate or not, punctures shallowly to deeply impressed. Preapical epipleural plica ( Fig. 22 View Figures 22–24 , ep) displaced outward, interrupting outline of elytra.

Hind wings. Macropterous or brachypterous.

Underside ( Fig. 2 View Figures 1–2 ). Metasternum with a row of setiferous punctures along margin of coxal cavity, median contact with abdomen dividing metacoxae. Suture between abdominal sterna III and IV obliterated at middle. Pleurite VII with small projection( Fig. 22 View Figures 22–24 , app) fitting into elytral epipleural plica (ep,).

Legs. Slender, protibia ( Figs 23, 24 View Figures 22–24 ) with basal half of ventral surface with a group of setae, protarsomeres in males slightly dilated.

Male genitalia ( Figs 25, 26 View Figures 25–26 ). Phallus lightly sclerotized; basal bulb with basal orifice (bo) oval, wide; basal projection (bp) distinct, apical margin curved; basal apophysis (ba) moderate; median portion tubular; apical portion formed by two lamellae (rl and ll). Endophallus pubescent in apical portion; basal sclerite (bs) clearly developed. Parameres subequal in length, the right one wider, both with 4-5 apical setae.

Female genitalia ( Figs 27, 28 View Figures 27–30 ). Ovipositor: gonocoxa (gc) unsegmented, very slender, with a pair of setae at apex, surface with micropores; laterotergites (lt) thinly sclerotized, flat and asetose, sclerotized border thin and folded in basal portion with a small anterior part; mediotergite (mt) wide, its width delimited by external borders of laterotergites. Reproductive tract: bursa copulatrix (bc) elongate; spermathecal duct (spd) =distance from apex of bursa copulatrix to insertion point of spermathecal gland duct (spgd) relatively short or long, spermathecal gland duct elongate; spermatheca (sp) various in thickness, length, and conformation; see description of this structure for each of the two species-groups.

Morphological notes.

Cuticular sculpture: The absence of a submarginal band of microsculpture on the proepisternum has been used to differentiate Semiardistomis from Ardistomis but the character state is not diagnostic since the band has been lost in at least two lineages of Ardistomis (Valdes, 2009).

The microsculpture on the elytral disc has a diagnostic value, the absence of microsculpture being the apotypic state.

Vestiture: Hirsuteness is a common phenomenon in this genus. In the two species groups, this apotypic character state appears, its origin independently developed. In the puncticollis group, three species have hirsute structures: Semiardistomis puncticollis from southern U.S.A. (supraorbital area of the head capsule, pronotal disc, elytral disc, profemur and abdominal sternum VII), Semiardistomis pilosellus (Kult) from southern South America (elytral disc and profemur) and Semiardistomis subglabra (van Emden) from South America (profemur). In the labialis group, two species have hirsute structures: Semiardistomis viridis from southern U.S.A. (pronotal disc and elytral disc) and Semiardistomis propinquus (Putzeys) from Mexico (elytral disc),

Elytra: In this genus, I regard the state of having the striae complete and impunctate as plesiotypic, being present in both species groups.

Hind wings: Macropterous except Semiardistomis laevistriatus brachypterous. Nichols (1988a) also reported that Semiardistomis puncticollis is brachypterous.

Legs: Protarsomeres in males so slightly dilated that this feature is useless for sex recognition.

Male genitalia: Phallic structure enhances definition of the two species groups of Semiardistomis . See details, provided in the species-group diagnoses. The differences in the phallic structures are too small to separate the species within each group, a situation also known in other clivinine genera, such as Schizogenius Putzeys (see Whitehead 1972).

Larvae.

The first instar of Semiardistomis was described by Bousquet (2006). It was compared with Ardistomis larva by Valdes (2007) who pointed out two notable synapotypic features: absence of the coronal suture and a segmented maxillary palpomere 4.

Classification.

Based primarily on male and female genitalic features, the species of Semiardistomis are arranged in two species-groups designated as the puncticollis and labialis group, respectively.

Criteria for species definition.

Of the 20 known species of Semiardistomis only those occurring in U.S.A. ( Semiardistomis viridis (Say) and Semiardistomis puncticollis (Dejean)) are represented by large series of specimens in collections ( Nichols 1988a; Bousquet 2006). The species inhabiting Central and South America and the West Indies are represented in collections by few specimens which give only an incomplete picture of the ranges of the species.

Members of this genus are difficult to identify in part because of a shortage of useful external features, and in part because the male and female genitalia, so useful in distinguishing between species groups, are not useful within each group. Moreover, some of the characters traditionally used to separate the species have been found in large samples to vary extensively. Some samples are a mixture of combinations from extreme patterns considered as different species; being impossible to demonstrate if those populations are hybrids or simply polymorphs, while in other putative species, allopatric populations exhibit no evident differences. In the labialis group in southern South America, the species limits are especially difficult to assess probably because the group is young and composed of species with a great power of dispersal. Without direct evidence of the state of gene flow between known populations, it is almost impossible to testify in favor of the reproductive isolation of each species described or in other cases to designate subspecies. I will follow a criterion with a practical value, so maybe for some species, taxonomic determination will denote unintentionally a combination of extreme characters shared by more than one biological species.

Geographical distribution.

( Figs 57 View Figure 57 - 59 View Figure 59 )The range of this genus is co-extensive with the range of the Ardistomina .

Key to described species of Semiardistomis , based on adult characters

1	Elytral disc plurisetose	2
1'	Elytral disc with setiferous punctures in interval 3, or sometimes also in interval 5	5
2(1)	Profemur plurisetose	3
2'	Profemur with the usual setae	4
3(2)	Pronotal disc plurisetose (along margin and on disc). Habitus as in Fig. 48 View Figures 47–48 . USA	Semiardistomis puncticollis (Dejean)
3'	Pronotal disc with the usual 2 pairs of marginal setae. Habitus as in Fig. 44 View Figures 41–44 . South America	Semiardistomis pilosellus (Kult)
4(2')	Pronotal disc plurisetose along margin. Habitus as in Fig. 55 View Figures 54–55 . USA	Semiardistomis viridis (Say)
4'	Pronotal disc with the usual 2 pairs of marginal setae. Habitus as in Fig. 54 View Figures 54–55 . Mexico	Semiardistomis propinquus (Putzeys)
5(1')	Elytron with two setiferous punctures on interval 3; humerus rounded; brachypterous. Habitus as in Fig. 47 View Figures 47–48 Guadeloupe	Semiardistomis laevistriatus (Fleutiaux & Sallé)
5'	Elytron with three or more setiferous punctures on interval 3; macropterous	6
6(5')	Elytron with three setiferous punctures on interval 3	7
6'	Elytron with more than three setiferous punctures on interval 3	12
7(6)	Elytral striae impunctate. Habitus as in Fig. 52 View Figures 51–52 . South America	Semiardistomis pallipes (Dejean)
7'	Elytral striae punctate	8
8(7')	Elytral disc with isodiametric mesh pattern	9
8'	Elytral disc smooth	10
9(8)	Elytral striae impressed only in basal fifth, punctures deep along three-quarters of elytra, surface completely covered with isodiametric mesh pattern. South America	Semiardistomis deletus (Putzeys)
9'	Elytral striae obliterated in apical third, punctures moderately deep, surface with isodiametric mesh pattern, evanescent in central area of elytral disc in some specimens. South America	Semiardistomis flavipes (Dejean)
10(8')	Elytral striae obliterated in apical fifth, punctures moderately deep. Habitus as in Fig. 51 View Figures 51–52 . West Indies	Semiardistomis cyaneolimbatus (Chevrolat)
10'	Elytral striae impressed only in basal fifth	11
11(10')	Elytral punctures deeply impressed in basal two-thirds of elytra. Habitus as in Figs 1, 2 View Figures 1–2 . Central America	Semiardistomis labialis (Chaudoir)
11 '	Elytral punctures moderately impressed in basal third of elytra. Southern South America	Semiardistomis semipunctatus (Dejean)
12(6')	Elytral disc surface completely covered with isodiametric mesh pattern. Habitus as in Fig. 46 View Figures 45–46 . South America	Semiardistomis maindroni (Kult)
12'	Elytral disc surface smooth	13
13(12')	Elytral striae complete; impunctate	14
13'	Elytral striae incomplete	17
14(13)	Front between antennal lobes with transverse rugae. Habitus as in Fig. 50 View Figures 49–50 . Southern Brazil	Semiardistomis rugosus
14'	Front between antennal lobes smooth	15
15(14')	Elytron with five setiferous punctures on interval 3; body size more than 7 mm. Habitus as in Fig. 49 View Figures 49–50 . Peru	Semiardistomis major n. sp.
15'	Elytron with four setiferous punctures on interval 3; body size less than 6 mm	16
16(15')	Pronotum markedly cordate, 1.25 times wider than long; humeri square, sides subparallel. Habitus as in Fig. 37 View Figures 37–38 . Colombia	Semiardistomis cordicollis (Putzeys)
16'	Pronotum subcordate, 1.14 times wider than long; shoulders rounded. Habitus as in Fig. 38 View Figures 37–38 . South America.	Semiardistomis exspectatus n. sp.
17(13')	Elytron with eight setiferous punctures in interval 3	18
17'	Elytron with four setiferous punctures in interval 3	19
18(17)	Elytron with three setiferous punctures in interval 5. Habitus as in Fig. 39 View Figures 39–40 . Brazil	Semiardistomis darlingtoni (Kult)
18'	Elytron with interval 5 asetose. Habitus as in Fig. 40 View Figures 39–40 . South America	Semiardistomis subglabra (van Emden)
19(17')	Elytral striae 3,4,5 and 6 impressed in basal half of disc, stria 2 present. Body length around 4 mm. Habitus as in Fig. 45 View Figures 45–46 . South America	Semiardistomis jedlickai (Kult)
19'	Elytral striae 3, 4, 5 and 6 impressed in basal third of disc, stria 2 absent. Body length around 6 mm. Habitus as in Fig. 41 View Figures 41–44 . South America	Semiardistomis glabratus (Putzeys)