Review Article |
Corresponding author: Olivia F. Boyd ( boydo@oregonstate.edu ) Academic editor: Lyubomir Penev
© 2016 Olivia F. Boyd, Terry L. Erwin.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Boyd OF, Erwin TL (2016) Taxonomic review of New World Tachyina (Coleoptera, Carabidae): descriptions of new genera, subgenera, and species, with an updated key to the subtribe in the Americas. ZooKeys 626: 87-123. https://doi.org/10.3897/zookeys.626.10033
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The classification of the carabid subtribe Tachyina (Trechitae: Bembidiini) is reviewed in light of newly discovered diversity from Central and South America. Described herein are three new genera (Tachyxysta gen. n., Stigmatachys gen. n., Nothoderis gen. n.), two new subgenera of Meotachys (Scolistichus subgen. n., Hylotachys subgen. n.), and two new subgenera of Elaphropus (Ammotachys subgen. n., Idiotachys subgen. n.). Two names previously synonymized under Polyderis (Polyderidius Jeannel, 1962) and Elaphropus (Nototachys Alluaud, 1930) are elevated to generic and subgeneric status, respectively. Eight new species are recognized: Tachyxysta howdenorum (type locality: México: Chiapas: El Aguacero, 680m); Elaphropus marchantarius (type locality: Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria), E. acutifrons (type locality: Brazil: Pará, Santarém) and E. occidentalis (type locality: Perú: Loreto, Pithecia, 74°45'W 05°28'S); Stigmatachys uvea (type locality: Perú: Loreto: Campamento San Jacinto, 2°18.75'S, 75°51.77'W, 175–215m); and Meotachys riparius (type locality: Colombia: Amazonas: Leticia, 700 ft), M. ballorum (type locality: Brazil: Amazonas, Rio Negro Cucui), and M. rubrum (type locality: Perú: Madre de Dios: Rio Manu, Pakitza, 11°56°47'S 071°17°00'W, 356m). An updated key to the genera and subgenera of Tachyina occurring in the New World is provided, with accompanying illustrations.
La clasificación de la subtribu Tachyina (Carabidae: Trechitae: Bembidiini) se revisa luego de diversidad que ha sido nuevamente descrita del Centro y Sur América. Aquí se describen tres géneros nuevos (Tachyxysta género nuevo, Stigmatachys género nuevo, Nothoderis género nuevo), dos subgéneros nuevos del Meotachys (Scolistichus subgénero nuevo, Hylotachys subgénero nuevo), y dos subgéneros nuevos del Elaphropus (Ammotachys subgénero nuevo, Idiotachys subgénero nuevo). Dos nombres taxonómicos previamente sinonimizados con Polyderis (Polyderidius Jeannel, 1962) y Elaphropus (Nototachys Alluaud, 1930) aquí son elevados a los niveles de género y subgénero, respectivamente. Se reconocen ochos espécies nuevos: Tachyxysta howdenorum (localidad tipo: México: Chiapas: El Aguacero, 680m); Elaphropus marchantarius (localidad tipo: Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria), E. acutifrons (localidad tipo: Brazil: Pará, Santarém) and E. occidentalis (localidad tipo: Perú: Loreto, Pithecia, 74°45'W 05°28'S); Stigmatachys uvea (localidad tipo: Perú: Loreto: Campamento San Jacinto, 2°18.75'S, 75°51.77'W, 175–215m); and Meotachys riparius (localidad tipo: Colombia: Amazonas: Leticia, 700 ft), M. ballorum (localidad tipo: Brazil: Amazonas, Rio Negro Cucui), and M. rubrum (localidad tipo: Perú: Madre de Dios: Rio Manu, Pakitza, 11°56°47'S 071°17°00'W, 356m). Una clave actualizada con illustraciones de los géneros y subgéneros del Tachyina que ocurren en el Nuevo Mundo está incluída.
A classificação da subtribo Tachyina (Carabidae: Trechitae: Bembidiini) está revisto à luz da diversidade recém-descrita da América Central e do Sul. Aqui são descritos três novos gêneros (Tachyxysta novo gênero, Stigmatachys novo gênero, Nothoderis novo gênero), dois novos subgêneros de Meotachys (Scolistichus novo subgênero, Hylotachys novo subgênero), e dois novos subgêneros de Elaphropus (Ammotachys novo subgênero, Idiotachys novo subgênero). Dois nomes taxonômicos anteriormente sinonimizadas com Polyderis (Polyderidius Jeannel, 1962) e Elaphropus (Nototachys Alluaud, 1930) são elevada aos níveis de gênero e subgênero, respectivamente. Oito espécies são reconhecidas: Tachyxysta howdenorum (localidade tipo: México: Chiapas: El Aguacero, 680m); Elaphropus marchantarius (localidade tipo: Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria), E. acutifrons (localidade tipo: Brazil: Pará, Santarém) and E. occidentalis (localidade tipo: Perú: Loreto, Pithecia, 74°45'W 05°28'S); Stigmatachys uvea (localidade tipo: Perú: Loreto: Campamento San Jacinto, 2°18.75'S, 75°51.77'W, 175–215m); and Meotachys riparius (localidade tipo: Colombia: Amazonas: Leticia, 700 ft), M. ballorum (localidade tipo: Brazil: Amazonas, Rio Negro Cucui), and M. rubrum (localidade tipo: Perú: Madre de Dios: Rio Manu, Pakitza, 11°56°47'S 071°17°00'W, 356m). Também está incluída uma chave atualizada com ilustrações dos gêneros e subgêneros de Tachyina que ocorrem no Novo Mundo.
Elaphropus , Meotachys , Nototachys , Polyderidius , Polyderis , Nothoderis , Stigmatachys , Tachyxysta , Amazon basin
The cosmopolitan carabid subtribe Tachyina includes about 800 described species. In the Americas, tachyine diversity is greatest in the tropics, with species documented from a wide variety of habitats (riparian, hypogean, arboreal, corticolous, myrmecophilous, etc.). Detailed accounts of New World tachyine natural history are provided in previous publications by
Among Bembidiini, tachyines are well-defined morphologically. All but a few tachyines have at least a trace of an elytral apical recurrent groove, which can vary in form (Fig.
Basic characters for generic and subgeneric level identification of Tachyina. A–B Left elytron, lateral view, illustrating positions of elytral ombilicate setae and form of the 8th elytral interneur (other interneurs omitted) A Paratachys fulvicollis; B Tachys vittiger C–F Elytral apex C Paratachys fulvicollis D Tachys vittiger. Scale bar 0.25 mm EElaphropus (Ammotachys) marchantariusF Tachyxysta howdenorum G–H Head, ventral view, illustrated to show mentum GMeotachys (Scolistichus) ripariusHElaphropus (Barytachys) nebulosus. Scale bars = 0.25 mm.
New Tachyina. A Stigmatachys uvea (holotype, ♀), Perú, Loreto, Campamento San Jacinto B Polyderidius sp., México, San Luis Potosí; C Nothoderis rufotestacea, USA, Arizona, Cochise Co. DMeotachys (Hylotachys) ballorum (paratype, ♀), Brazil, Amazonas, Tapurucuara EElaphropus (Ammotachys) marchantarius (paratype, ♂), Venezuela, San Carlos de Rio Negro FMeotachys (Scolistichus) riparius (paratype, ♀), Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria; GElaphropus (Idiotachys) acutifrons (holotype, ♀), Brazil, Santarem HElaphropus (Nototachys) occidentalis (paratype, ♂), Perú, Madre de Dios, Pakitza I Tachyxysta howdenorum (holotype, ♂), México, Chiapas, El Aguacero. Scale bars = 0.5 mm.
Among the “non-bifoveate’ Tachyina (
Codes for the institutions where type material will be deposited appear in the text as follows:
UNMSM Museo Historia Natural, San Marcos University, Lima Perú; Gerardo Lamas, Curator
DNA voucher specimens representing some of the taxa described were available from a separate project. Males were dissected following DNA extraction. Genitalia were cleared in KOH and mounted in Euparal following the procedure described by
External structures were examined using a Leica M165 C dissecting microscope. Measurements were taken digitally using a camera-equipped Leica Z6 and the software Cartograph (Microvision). Measurements represent a range from the smallest to largest specimen examined. Abbreviations and definitions of measurements provided are listed below. Photomicrographs obtained with this system were compiled into stacked images using the photomontage software Zerene Stacker (Zerene Systems). Digital illustrations were prepared from reference photos using Adobe Creative Cloud software tools (Adobe Systems 2015).
Morphological terms generally follow the conventions established by
i1 elytral interneur 1 (closest to suture)
i8 elytral interneur 8 (closest to lateral margin)
Ed elytral discal seta
Eo elytral ombilicate seta
ABL apparent body length (labrum to elytral apex of specimen in horizontal view)
SBL standardized body length (labrum to posterior supraorbital seta + pronotum from base to apex at center line + base of scutellum to elytral apex)
TW total width across widest point of both elytra
ARG elytral apical recurrent groove
Label data are listed verbatim, with label breaks denoted as follows: “label data” / “begin new line on label” // “begin second label”.
Genus (Subgenus) # described species occurring in the Americas
Moirainpa Erwin, 1984 1
Micratopus Casey, 1914 5
Lymnastis Motschulsky, 1862 2
Costitachys Erwin, 1974 2
Tachyta Kirby, 1837
(Tachyta) 6
Tachyxysta gen. n. 1
Elaphropus Motschulsky, 1839
(Tachyura Motschulsky, 1862) 2
(Barytachys Chaudoir, 1868) 38
(Ammotachys subgen. n.) 1
(Idiotachys subgen. n.) 1
(Nototachys subgen. n.) 1
Porotachys Netolitsky, 1914 1
Polyderis Motschulsky, 1862
(Polyderis) 1
Liotachys Bates, 1871 1
Tachysbembix Erwin, 2004 2
Tachys Dejean, 1821 15
Paratachys Casey, 1918 50
Polyderidius Jeannel, 1962 8
Stigmatachys gen. n. 1
Nothoderis gen. n. 3
Meotachys Erwin, 1974
(Meotachys) 8
(Scolistichus subgen. n.) 1
(Hylotachys subgen. n.) 2
Pericompsus LeConte, 1851
(Pericompsus) 49
(Eidocompsus Erwin, 1974) 13
1 | Mentum normal for Carabidae, afoveate (Fig. |
2 |
– | Mentum with pair of paramedial, rather deep circular foveae (Fig. |
13 |
2(1) | Elytral intervals carinate; pronotum with longitudinal carinae | Costitachys Erwin, 1974 |
– | Elytron and pronotum not carinate | 3 |
3(2’) | Labrum bilobed, covering mandibles; elytron truncate, pubescent; ARG barely impressed or absent | 4 |
– | Labrum truncate; elytron various; ARG various | 5 |
4(3) | Head with single pair of supraorbital setae; male and female both with two pairs apical abdominal ventral setae, lateral pair sickle-shaped | Micratopus Casey, 1914 |
– | Head with two pairs of supraorbital setae; apical abdominal ventrite of male with 2 longer setae, female with 4 (Old World—adventive) | Lymnastis Motschulsky, 1852 |
5(3’) | Form depressed; ARG absent; body dorsally pubescent; eyes reduced, with a few large facets | Moirainpa Erwin, 1984 |
– | Form convex to subdepressed; ARG visible, feebly to markedly impressed; body dorsally glabrous or (rarely) sparsely setose | 6 |
6(5’) |
ARG elongate, subparallel to elytral margin (Figs |
7 |
– |
ARG very short (Figs |
9 |
7(6) | Tarsal claws denticulate; prosternum plurisetose; body dorsoventrally compressed, dorsal surface coarsely microsculptured | Tachyta Kirby, 1837 |
– | Tarsal claws simple; prosternum glabrous; body convex to subdepressed; dorsal surface various | 8 |
8(7’) | Dorsal surface with coarse, isodiametric microsculpture; ARG straight; form subdepressed; color light brown; pronotum without basal excavation (Pan-tropical—adventive) | Elaphropus yunax (Darlington, 1939) |
– | Dorsal surface without microsculpture, except for labrum; ARG sinuate, slightly hooked anteriorly; form robust, convex (Fig. |
Tachyxysta gen. n. |
9(6’) | Humeral series of elytral ombilicate punctures evenly spaced or symmetrically distributed, with d(1,2) = d(3,4) (Fig. |
10 |
– | Humeral series of Eo punctures asymmetrically distributed, with Eo4 removed from closely grouped Eo1–3 such that d(3,4) > d(1,2) and d(3,4) > d(2,3) (Fig. |
11 |
10(9) | Elytron with 8 micropunctulate interneurs; i4–7 not reaching apex and i4–5 converging apically (Figs |
Elaphropus (Ammotachys) subgen. n. |
– | Elytron with 1–2 punctate interneurs (Fig. |
Elaphropus (Idiotachys) subgen. n. |
11(9’) | Pronotum longer than wide, constricted at base (Fig. |
Elaphropus (Nototachys) Alluaud, 1930 |
– | Pronotum subquadrate to transverse and cordiform; elytron with 4 discal setae, antennae concolorous | 12 |
12(11’) | i8 interrupted at middle; mesepisternum with one or more shallow fovea(e) or punctures | Elaphropus (Barytachys) Chaudoir, 1868 |
– | i8 entirely impressed, subparallel to elytral margin | Elaphropus (Tachyura) Motschulsky, 1862 |
13(1’) | Head with 3 pairs supraorbital setae (Fig. |
Polyderidius Jeannel, 1962 |
– | Head with 2 pairs supraorbital setae | 14 |
14(13’) | Pronotum markedly constricted basally; i8 absent externally; form “ant-like”; apical half of antennae usually lighter than basal half, often whitish | Liotachys Bates, 1871 |
– | Pronotum cordiform to quadrate; i8 variable in shape and completeness; overall form not as above | 15 |
15(14’) |
ARG elongate, very close to and parallel with elytral margin (see Fig. |
Porotachys Netolitzky, 1914 |
– |
ARG varied in form (very faint to markedly impressed, short to elongate, simple or hooked), but not parallel to elytral margin (directed anteriorly toward elytral disc or closer to suture than margin) (see Figs |
16 |
16(15’) | ARG anteriorly hooked around, into, or effaced laterad of 4th discal seta | 17 |
– | ARG simple, not hooked, short to elongate | 19 |
17(16) |
ARG hooked into or effaced laterad of 4th discal seta (Fig. |
Tachys s. str. Stephens, 1829 |
– | Hook of ARG either surrounding or produced laterad of 4th discal seta; i8 medially incurved, diverted from elytral margin at Eo5–6 | 18 |
18(17’) |
ARG hooked around 4th discal seta (Fig. |
Paratachys Casey, 1918 |
– | Hook of ARG produced laterad of 4th discal seta; width across eyes at widest point about equal to greatest width of pronotum; i8 shallow; surface dull, with coarse, granulate microsculpture; specimen from sea coast | Tachysbembix Erwin, 2004 |
19(16’) | Pronotum convex, with barely rounded hind angles; i8 reduced, faintly visible apically, not redirected around elytral ombilicate setae | Polyderis s. str Motschulsky, 1862 |
– | Pronotum shallowly convex to subdepressed, with square to acute posterior angles; i8 partially to completely impressed, apically diverted around Eo5–6, Eo7 OR interneurs deeply punctate and reduced in number | “Pericompsus / Meotachys complex” 20 |
20(19’) | Pronotum with continuous, punctate transverse impression, usually arcuate (forming crescent-shaped basal section), sometimes bilobed; i8 with conspicuous posthumeral foveae or fovea, usually at basal fourth or midpoint OR elytron with 8 entirely punctate interneurs; elytra with or without color pattern or macula(e) | Pericompsus 25 |
– | Pronotum with punctate or subsulcate transverse impressions converging at medial furrow, forming triangular basal section (see Fig. |
21 |
21(20’) | Elytral humeri obliquely rounded (possibly brachypterous), margins serrate; elytron with at most 6 deeply punctate interneurs (Fig. |
Stigmatachys gen. n. |
– | Elytral humeri squarely rounded, margins smooth or serrate (Fig. |
22 |
22(21’) | Elytral interneurs distinctly punctate, fewer than 8 entirely visible | Meotachys s. str. Erwin, 1974 |
– | Elytral interneurs micropunctulate to striatiopunctate, up to 8 entirely visible | 23 |
23(22’) | Pronotum transversely cordate, margins sinuate, posterior angles prominent and slightly acute (Fig. |
Meotachys (Hylotachys) subgen. n. |
– | Pronotum transversely quadrate, margins subparallel to slightly sinuate, posterior angles approximately square (Fig. |
24 |
24(23’) | Elytral margin partially to entirely serrate; i8 feebly to moderately impressed from Eo5 to apex, separated from elytral margin by Eo5–8 but not markedly curved in apical half (Fig. |
Nothoderis gen. n. |
– | Elytral margin smooth (Fig. |
Meotachys (Scolistichus) subgen. n. |
25(20) | i8 with a deep, nearly perforate fovea at or just anterior to middle of elytron; elytron with two additional subhumeral foveae of varied size; pronotum often narrowed at base; body typically elongate; elytra often with dark markings | Pericompsus s. str. LeConte, 1852 |
– | i8 not foveate at or near middle of elytron; if foveate posterior to humerus, then fovea shallow and bearing seta OR small, perforate, and located at basal fourth near seta Eo4c; pronotum usually quadrate, with base and apex subequal in width; body typically compact, robust, unicolorous | Pericompsus (Eidocompsus) Erwin, 1974 |
Pronotum, dorsal aspect. A Stigmatachys uvea (holotype, ♀), Perú, Loreto, Campamento San Jacinto B Polyderidius sp., México, San Luis Potosí C Nothoderis rufotestacea, USA, Arizona, Cochise Co. DMeotachys (Hylotachys) ballorum (paratype, ♀), Brazil, Amazonas, Tapurucuara EElaphropus (Ammotachys) marchantarius (paratype, ♂), Venezuela, San Carlos de Rio Negro FMeotachys (Scolistichus) riparius (paratype, ♀), Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria; GElaphropus (Idiotachys) acutifrons (holotype, ♀), Brazil, Santarem HElaphropus (Nototachys) occidentalis (paratype, ♂), Perú, Madre de Dios, Pakitza I Tachyxysta howdenorum (holotype, ♂), México, Chiapas, El Aguacero. Scale bars = 0.25 mm.
Illustrations of left elytron, lateral view, showing variation in the form of the 8th elytral interneur (other interneurs not shown) among newly described taxa. A Stigmatachys uvea (holotype, ♀) B Polyderidius sp. C Nothoderis sp. DMeotachys (Scolistichus) riparius; EMeotachys (Hylotachys) ballorum; FElaphropus (Ammotachys) marchantariusGElaphropus (Idiotachys) acutifronsHElaphropus (Nototachys) occidentalisI Tachyxysta howdenorum. Scale bars = 0.25 mm.
Elytral apex, left dorsal oblique view. A Stigmatachys uvea (holotype, ♀), Perú, Loreto, Campamento San Jacinto B Polyderidius sp., México: San Luis Potosí C Nothoderis rufotestacea, USA: AZ: Cochise Co. DMeotachys (Hylotachys) ballorum (paratype, ♀), Brazil, Amazonas, Tapurucuara EElaphropus (Ammotachys) marchantarius (paratype, ♂), Venezuela, San Carlos de Rio Negro FMeotachys (Scolistichus) riparius (paratype, ♀), Brazil, Amazonas, Rio Solimões, Ilha de Marchantaria GElaphropus (Idiotachys) acutifrons (paratype, ♀), Brazil, Santarem HElaphropus (Nototachys) occidentalis (paratype, ♂), Perú, Madre de Dios, Pakitza I Tachyxysta howdenorum (holotype, ♂), México, Chiapas, El Aguacero. Scale bars = 0.25 mm.
Illustrations of aedeagus, left lateral aspect, with parameres (left and right) shown below median lobe. AMeotachys (Hylotachys) ballorum, DRM voucher DNA2854 B Nothoderis sp., DRM voucher DNA2870 C Nothoderis sp., DRM voucher DNA2935 D Polyderis laeva, DRM voucher DNA2913 E Tachyxysta howdenorum, DRM voucher 4881 F Nothoderis rufotestacea, DRM voucher DNA0718. Scale bars = 0.1 mm.
Moirainpa amazona Erwin, 1984.
Mentum without foveae; eyes reduced and pubescent, with a few large facets; labrum not covering mandibles; foretibia notched apicolaterally; elytron entire, with serrate humeral margin; ARG absent; body subdepressed, pubescent. ABL = 1.0 mm.
Known from várzea white water inundation forests of the upper to middle Amazon River drainage (
Blemus aenescens (LeConte, 1848).
Mentum without foveae; labrum bilobed, covering mandibles; head with single pair of supraorbital setae; elytra truncate; terminal abdominal ventrite of both male and female with four long setae, the lateral pair sickle-shaped. ABL = 1.2–3.0 mm.
Often abundant at lights, this speciose and underdescribed genus is known from southern North America to northern South America and the Caribbean (
Lymnaeum indicum (Motschuslky, 1851).
Mentum without foveae; labrum bilobed, covering mandibles; head with two pairs of supraorbital setae; elytra slightly truncate; terminal abdominal ventrite of male with two long, straight setae, female with four long, straight setae; body densely to sparsely setose.
This Old World genus is adventive in Hawaii and the Caribbean (
Costitachys inusitatus Erwin, 1974.
Mentum without foveae; foretibia with apicolateral notch; body subdepressed, flavotestaceous, shiny; head with single pair of supraorbital setae; basal protarsomere of male dilated, medially dentiform; head (3), pronotum (5), and elytron (8) with prominent longitudinal carinae; ABL = 1.7–2.6 mm.
Known from sandy riparian habitats throughout the Amazon basin, from the eastern Andes of Ecuador and Perú to the Atlantic coast of South America (Erwin 1974;
Tachyta picipes Kirby, 1837.
Elongate, subdepressed; mentum lacking foveae; dorsal surface (excluding Old World taxa) with coarse, isodiametric microsculpture; prosternum plurisetose; tarsal claws denticulate; basal two protarsomeres of male dilated, medially dentiform; ARG elongate, slightly hooked anteriorly, close and subparallel to lateral margin of elytron. ABL = 1.8–3.3 mm.
Widely distributed from the boreal Nearctic to Central America and the Caribbean, associated with fallen logs (
Tachyxysta howdenorum Boyd & Erwin, sp. n.
Pronotum with distinctly inflated basal section separated from pronotal disc by subsulcate transverse impression; basal section interrupted at midpoint by prominent, deep excavation opposite scutellum; overall form robust, convex.
Size. ABL = 2.4–2.5 mm; SBL = 2.5–2.7 mm; TW = 1.15–1.25 mm.
Form. Compact, robust, convex.
Color. Dorsally piceous, unicolorous (Fig.
Head. Two pairs of supraorbital setae within channeled longitudinal frontal furrows; frons not raised between furrows, often with subtle transverse wrinkles (Fig.
Prothorax. Base of pronotum (Fig.
Pterothorax.Elytral margin reflexed; i1 entire, subsulcate or faintly impressed; i2–i7 not visible; i8 striatiopunctate from humerus to Eo5, apically subsulcate (Fig.
Genitalia. male aedeagus robust, elongate, with unequally sized, apically 3- or 4-setose parameres (Fig.
The Mexican specimens were collected near or in El Ocote Preserve; the Honduran specimen was collected in an area near Comayagua National Park. Based on collection data from a limited number of specimens, T. howdenorum may be restricted to higher altitudes.
Feminine. Derived from Tachys, the nominate genus of the subtribe Tachyina, and the Greek xustos (=“smooth/polished”), in reference to this species’ unmicrosculptured, glabrous dorsal surface and alluding to its general resemblance to some members of the subtribe Xystosomina, particularly those of the genus Erwiniana.
Holotype: male (
México: Chiapas: El Aguacero.
Size, form, color, head, prothorax, pterothorax, abdomen, genitalia, and distribution as in description of the genus.
The patronym howdenorum honors Henry and Anne Howden, collectors of the holotype. The Howdens collected several examples included in the type series of T. howdenorum two decades apart in different locations.
Despite its superficial resemblance to the genus Xystosomus, T. howdenorum possesses a combination of characters that support its placement among the Tachyina but discourage its membership in any previously described tachyine genus; T. howdenorum has an apicolaterally notched protibia and an apical recurrent groove reminiscent of Tachyta, but lacks the denticulate tarsal claws diagnostic for that genus (Erwin, 1975).
Elaphropus caraboides Motschulsky, 1862.
Mentum lacking foveae; claws simple; prosternum glabrous; elytron with 2 to 8 visible interneurs, complete or not, and variable in form; i8 impressed entirely or effaced at midpoint or visible only near apex; ARG short, straight or medially arcuate or if elongate and parallel to elytral margin, not recurved anteriorly.
Elaphrus quadrisignatus Duftschmidt, 1812.
i8 impressed from base to apex, subparallel to elytral margin, inserted anteriorly between Eo2 and Eo3; humeral series of elytral ombilicate setal insertions asymmetrically distributed, with Eo4 removed from closely grouped Eo1–3 such that d(3,4) > d(1,2) and d(3,4) > d(2,3); ARG short, straight to medially arcuate or elongate, straight, and parallel to elytral margin (E. yunax).
Old World, Australia; adventive in the Americas.
Bembidium incurvum Say, 1834.
i8 visible near base and apex, middle section effaced; humeral series of elytral ombilicate setal insertions asymmetrically distributed, with Eo4 removed from closely grouped Eo1–3 such that d(3,4) > d(1,2) and d(3,4) > d(2,3); ARG short, straight or medially arcuate.
North and Central America, the Caribbean islands.
Elaphropus marchantarius sp. n.
Mentum lacking foveae; elytron (Fig.
Size. ABL = 2.25–2.8 mm; SBL = 2.35–2.9 mm; TW = 0.95–1.15 mm
Form. Elongate, parallel-sided, subdepressed.
Color. Uniformly yellow-brown to flavous.
Microsculpture. Head and anteromedial part of pronotum with coarse, scaly, isodiametric microsculpture; remainder of pronotum and elytron with linear, transverse microsculpture.
Head. Mentum without foveae.
Prothorax. Basal section of pronotum (Fig.
Pterothorax. Elytral margin serrate; humeral margin (Fig.
Genitalia. Not examined.
Widely distributed in the Amazon basin. Known from several localities along the Rio Negro (S. Venezuela), Rio Solimões (S. Colombia and Pará, Brazil), and their confluence, and the Rio Xingu (NE Mato Grosso, Brazil).
Masculine. Greek noun, ammos (= “sand”), in reference to the habitat and coloration of the known species of this genus, and Tachys, the nominate genus of the subtribe Tachyina.
Though these beetles are tentatively placed within Elaphropus due to the afoveate mentum, their remarkable (though perhaps homoplasious) resemblance to the foveae-bearing species Meotachys (Scolistichus) riparius, calls into question the long-assumed taxonomic value and phylogenetic distribution of this character. These two species have similarly broad, pan-Amazonian, apparently overlapping distributions. Molecular data should help to clarify whether their shared morphologies are due to convergence of separate lineages or the loss or gain of foveae within a lineage.
Holotype: male (
Brazil: Amazonas: Rio Solimões, Ilha de Marchantaria, 59°58'W 3°15'S.
Size, form, color, microsculpture, head, prothorax, mesothorax, and distribution as in description of the subgenus.
The specific epithet marchantarius is a toponym referring to Ilha de Marchantaria, the collection locality of the majority of type material, located near Manaus, Brazil.
Elaphropus acutifrons sp. n.
Mentum without foveae; head with prominent keel-like frontoclypeal carina; elytral interneurs punctate, incomplete in length, and reduced in number; i8 visible only in apical half, interrupted and reduced.
Size. ABL = 2.15–2.2 mm; SBL = 2.25–2.325; TW = 0.95–1.0 mm.
Form. (Fig.
Color. Dark reddish brown, glabrous with some small punctules.
Microsculpture. Apparently absent, but difficult to see due to specimen condition.
Head. Mentum without deep foveae but with very faint, shallow impressions at base; frons (Fig.
Prothorax. Pronotum (Fig.
Pterothorax. Mesepisternum neither foveate nor perforate; elytral interneurs 1–2 punctate, with second effaced near apex; i3 only very faintly impressed (Figs
Genitalia. Not examined.
Known only from the type locality of Santarém, Pará, Brazil.
Masculine. From the Greek adjective ídios (=“self/peculiar”), in reference to its unique combination of characters, and Tachys, the nominate genus of the subtribe Tachyina.
Based on its afoveate mentum and apicolaterally notched protibiae, the only known species of Idiotachys is considered to be part of the greater Elaphropus complex. The overall proportions, reduced and punctate elytral strial interneurs, reduced 8th interneur, and arrangement of humeral elytral ombilicate setae diagnostic for the species described below preclude its placement in any existing Elaphropus subgenus.
These, along with unique external characters, support Idiotachys as a lineage distinct from either Tachyura or Barytachys, the two subgenera it most closely resembles.
Holotype: female (
Brazil: Pará, Santarém.
Form, size, color, head, prothorax, pterothorax, and distribution as in description of the subgenus.
Derived from the Latin acutus (=“sharp”) and frons (=“front”), in reference to this species’ distinctive raised frons.
Tachys comptus Andrewes, 1922
Mentum without paired foveae; antennae apically lighter than at base (Fig.
Southern Africa, South Asia, and South America.
Holotype: male (
Perú: Loreto, Pithecia, 74°45'W, 05°28'S.
Mentum without foveae; elytron smooth, with two pale maculae and 5 discal setae, Ed1–3 closely grouped in basal third (Fig.
Size. ABL = 2.0–2.4 mm; SBL = 2.4–2.7 mm; TW = 1.0–1.2 mm.
Form. (Fig.
Microsculpture. Absent except for isodiametrically microsculptured labrum.
Color. Glabrous, rufotestaceous to piceous; elytron with two pale maculae.
Head. Mentum without foveae; frons without longitudinal depressions; frontoclypeal suture with very short lateral subfoveate grooves extending posteriad; apical half of antennae abruptly lighter that basal half, nearly white in many specimens.
Prothorax. Pronotum (Fig.
Pterothorax. Mesepisternum (Fig.
Genitalia. Not examined.
Known from Perú, Brazil, and Argentina. Widespread and apparently abundant in—though not restricted to—riparian habitats.
Derived from the Latin occidens (=“west”), in reference to the New World precinctiveness of this species. This subgenus was previously only described from the Old World.
Trechus bisulcatus Nicolai, 1822
Large in size (> 4 mm); mentum bearing paired foveae; pronotum quadrate, with square to acute hind angles; base of elytra wider than pronotum; elytra round, convex, with width across elytra conspicuously greatest at midpoint; ARG elongate, straight, very close to and subparallel with lateral margin of elytron.
Palearctic—adventive in North America.
Tachys brevicornis Chaudoir, 1846
Very small (< 2 mm), mentum bearing paired foveae; pronotum convex, posterior angles squarely rounded or slightly obtuse; antennae short, submoniliform; i8 reduced, barely impressed, visible apically; ARG very short.
Old World and Australia, with a single species (P. laeva) in the Americas.
Liotachys antennatus Bates, 1871.
Overall form “ant-like”; antennae lighter apically than at base; pronotum pedunculate, slender at base and lacking produced hind angles; mentum bearing paired foveae; elytron smooth, with only i1 visible (subsulcate); i8 not visible; ARG short and arcuate.
Amazon basin.
Tachysbembix sirena Erwin, 2004.
Mentum bearing paired foveae; anterior tibia with apicolateral notch; dorsal surface dull, with coarse, granulate microsculpture; head and eyes large; head and pronotum subequal in greatest width; pronotum round, subcordiform; pronotal hind angles tiny, laterally produced; i8 slightly bent around Eo5–6; ARG elongate, anterior hook laterally remote from 4th discal seta. ABL = 3.3–3.9 mm.
Known from shoreline habitats along the Pacific coast of Costa Rica (
Tachys scutellaris Stephens, 1828.
Mentum bearing paired foveae; protibia with apicolateral notch; dorsal surface typically with isodiametric microsculpture; pronotum subquadrate; i8 not markedly diverted around Eo5–6 (Fig.
Typically halophilic (
Tachys austinicus Casey, 1918.
Mentum bearing paired foveae; protibia with apicolateral notch; dorsal surface typically with transverse linear microsculpture and slight iridescence; pronotum subquadrate; i8 conspicuously bent around Eo5–6 (Fig.
Diverse habitats, cosmopolitan.
Polyderidius rapoporti Jeannel, 1962 by original designation.
Mentum with paired, circular foveae; head with three pairs of supraorbital setae (Fig.
Size. ABL = 1.0–1.2 mm; SBL = 1.1–1.3 mm; TW = 0.45–0.5 mm.
Form. Minute, delicate, dorsolaterally compressed.
Color. (Fig.
Microsculpture. Varied, from coarse/scaly/isodiametric to fine/linear/transverse.
Head. Head with three pairs of supraorbital setae (Fig.
Prothorax. (Fig.
Pterothorax. Elytral interneurs (if visible) punctate to striatiopunctate and very faintly impressed; i1 often entire, striatiopunctate; no trace of i8; apical recurrent groove (Fig.
Abdomen. Terminal ventrite with two (male) or four (female) elongated setae.
Genitalia. See
Known from across South and Central America, México, the southeast United States (Alabama, Mississippi), Hawaii, and islands of the Caribbean (Puerto Rico, Cuba) with the greatest species diversity in the Amazon basin (
Stigmatachys uvea sp. n.
Mentum bifoveate; antennae submoniliform; eyes reduced; labial subulate palpomere absent or reduced; lateral margin of pronotum sinuate; elytral humerus rounded; elytral interneurs punctate and reduced in number, with punctures becoming irregular near apex; abdominal sclerites densely and irregularly punctate.
Size. ABL = 1.2 mm; SBL = 1.35 mm; TW = 0.6 mm.
Form. (Fig.
Color. Reddish brown, with lighter appendages.
Microsculpture. Mostly absent, with local patches of isodiametric microsculpture at base of head and around eyes.
Head. (Fig.
Prothorax. (Fig.
Pterothorax. Mesepisternum without pits or foveae; humeral angles obliquely rounded; elytra oval, convex, each elytron (Fig.
Abdomen. Ventrites densely punctate and moderately setose.
Genitalia. Not examined.
Known only from the type locality in Loreto, Perú.
Masculine. Derived from the Greek noun stigma (=“mark” or “puncture”), in reference to the coarsely punctate elytra of the lone representative of this genus, and Tachys, the nominate genus of the subtribe Tachyina.
Holotype: female (
Perú: Loreto: Campamento San Jacinto, 2°18.75'S, 75°51.77'W, 175–215m.
Size, form, color, microsculpture, head, prothorax, pterothorax, abdomen, and distribution as in description of the genus.
Derived from the Latin noun uvea (=“grape”), referring to the ovate shape of the elytra of the holotype in dorsal view.
Tachys rufotestacea Hayward, 1900.
Mentum with paired circular foveae; posterior angles of pronotum square to slightly acute (Fig.
Size. ABL = 1.5–2.4 mm; SBL = 1.6–2.5 mm; TW = 0.6–1.0 mm.
Form. Small to minute, compact to elongate and subdepressed.
Color. Flavotestaceous to rufotestaceous.
Microsculpture. Varied; head and pronotum usually with isodiametric microsculpture; elytra with linear/transverse microsculpture or (rarely) glabrous.
Head. Mentum bifoveate; head with two pairs of supraorbital setae.
Prothorax. (Fig.
Pterothorax. (Fig.
Genitalia. (Based on male genitalia dissected and examined from single individuals of four different species) Male (Fig.
Known from North, Central, and Amazonian South America.
Feminine. Greek adjective nothos (=“false/spurious”), in reference to this diverse and New World-restricted group’s misleading taxonomic history, and deris (=“fight” (
Species of Nothoderis are united by the shape of the pronotum, course of the eighth elytral interneur, features of male genitalia, form of the elytral apical recurrent groove, and preliminary molecular evidence. Male genitalia of Polyderis laeva were also examined and illustrated, and differ notably from all examples of Nothoderis in the form of the internal sclerite(s) and parameres (Fig.
Tachys ampicollis Bates, 1882.
Subdepressed to dorsally convex; testaceous to rufous; mentum bearing paired circular foveae; foretibia notched apicolaterally; basal protarsomere of male dilated, medially dentiform; mesepisternum with or without small fovea; elytral strial interneurs varied in form, punctate to striatiopunctate; i8 apically curvy, diverted medially at Eo5–6 and Eo7; ARG short and arcuate or rudimentary and continuous with i3. ABL = 1.2–4.6 mm.
Meotachys species occupy diverse habitats and are described from México to southern Brazil (Erwin 1974,
Meotachys riparius sp. n.
Pronotum and elytra with fine, linear, transverse microsculpture; pronotum quadrate; mesepisternum without fovea(e); elytron with smooth margin and 8 micropunctulate interneurs, 4–7 not extended to apex; apical recurrent groove rudimentary, continuous with i3.
Size. ABL = 2.3–2.35; SBL = 2.475–2.55; TW = 1.05–1.075 mm.
Form. Elongate, subdepressed.
Color. (Fig.
Microsculpture. Microsculpture of anterior part of head coarse, scaly, isodiametric; pronotal and elytral microsculpture transverse, linear; elytral surface with slight iridescence.
Head. Mentum bifoveate; frontoclypeal suture very faint, with shallow lateral impressions.
Prothorax. (Fig.
Pterothorax. Elytral margins smooth; elytron (Fig.
Genitalia. Not examined.
Known from localities across the Amazon basin, from the upper Rio Negro system to the Rio Napo in Ecuador and northeastern Perú, and the lower Solimões River near Manaus.
Masculine. From the Greek skolios (=“crooked”), and stíchos (=“line”/“row”), in reference to the diagnostic curved 8th interneur.
Holotype: male (
Colombia: Amazonas: Leticia, 700 ft.
Form, color, head, prothorax, mesothorax, and abdomen as in description of the subgenus.
Derived from Latin ripa (=“river bank/edge”), in reference to the riparian habitats throughout the Amazon basin from which this species is known.
Meotachys ballorum sp. n.
Mentum bifoveate, antennae long and slender, pronotal margins sinuate, mesepisternum with single small, deep, reniform pit (Fig.
Size. ABL = 2.7–3.3 mm; SBL = 2.8–3.4 mm; TW = 1.2–1.5 mm.
Form. (Fig.
Color. Matte and dark brown to piceous or glabrous and dark red-brown.
Microsculpture. Varied.
Head. Mentum bifoveate; antennae long, about 2/3 ABL; frons (Fig.
Prothorax. Pronotum (Fig.
Pterothorax. Mesepisternum with single, small, reniform pit/fovea, with opening directed slightly posteriad (Fig.
Known from the type locality in Ecuador, as well as 4 localities along the Rio Negro, northern Amazonas, Brazil, and southern Perú.
Masculine. From the Greek hyle (=“wood/forest”, “matter/substance”), in reference to the association of species of this genus with Amazonian inundation forest habitats and the unique suite of characters uniting the two species, and Tachys, the nominate genus of the subtribe Tachyina.
Holotype: male (
Brazil: Amazonas, Rio Negro Cucui.
Head and abdomen as in description of the genus.
Size. ABL = 3.2–3.3 mm; SBL = 3.3–3.4 mm; TW = 1.4–1.5 mm.
Form. (Fig.
Color. Uniformly dark brown and slightly iridescent.
Microsculpture. Pronotum and elytron with very fine, linear, transverse microsculpture; head with coarse, isodiametric microsculpture.
Prothorax. Pronotum (Fig.
Pterothorax. Elytra broad and parallel-sided, narrowed beginning at apical third, 5–6 visible strial interneurs, first two complete (Fig.
Genitalia. Male (Fig.
Known from Brazil, Ecuador, and Colombia.
Patronym in honor of George and Kay Ball, who collected the major part of the type series on their 1978 expedition to Brazil.
The habitat of this species was mistakenly regarded as várzea. In fact the specimens were collected in igapó forest (Ball, personal communication, 2016)
Holotype: male (
Perú: Madre de Dios: Rio Manu, BIOLAT Biol. Sta., Pakitza, 11°56°47'S 071°17°00'W, 356m.
Head and abdomen as in description of the genus.
Size. ABL = 2.7–2.85 mm; SBL = 2.8–2.9 mm; TW = 1.2–1.3 mm.
Form. Head and prothorax slender, elytra rounded and convex.
Color. Uniformly rufotestaceous, shiny.
Microsculpture. Head, pronotum and elytron smooth, glabrous.
Prothorax. Pronotum subequal in length and width.
Pterothorax. Elytra somewhat round and convex, each with 2–3 visible strial interneurs, only i1 completely impressed; i5 position without visible stria, but with gently sloping “shelf” which originates at tip of elytral basal margin and separates basal elytral disc from humeral region.
Genitalia. Not examined.
Known only from the type locality in the Madre de Dios region of southeastern Perú.
Latin rubrum (=“red/crimson”), in reference to the deep red-brown color of this species.
Note: The holotype will be deposited in UNMSM and is currently held in trust until the completion of studies at
Bembidium ephippiatum Say, 1834.
Mentum with paired foveae; pronotum with continuous, punctate transverse impression; basal transverse impression arcuate or lobed, forming crescent-shaped or bilobed basal section; elytron either with one to two conspicuous subhumeral fovea(e) along i8 in basal fourth or with 8 entirely punctate interneurs; elytra with or without color pattern. ABL = 1.72–3.72 mm. (
Australia and the Americas.
Bembidium ephippiatum Say, 1834.
Typically elongate, subcylindrical in form; pronotum quadrate to narrowed in basal fourth; elytral i8 with a deep fovea at or just anterior to midpoint of elytron and two smaller, subhumeral foveae of variable size; elytral interneurs punctate to striatiopunctate; elytra usually testaceous with darker markings resembling ink blotches. ABL = 1.88–3.72 mm. (
Species of this subgenus are numerous and described from across the New World between the temperate mid-latitudes of North and South America and some of the Caribbean islands.
Trechus brasiliensis Sahlberg, 1844.
Broad and robust, depressed to subcylindrical in form; pronotum quadrate, subequal in width at base and apex; elytra usually unicolorous; elytral interneurs punctate; i8 subsulcate and not bearing fovea(e) at or near middle of elytron; i8 with or without subhumeral fovea: if present, then fovea shallow and bearing seta or small, perforate, and located at basal fourth near seta Eo4; if i8 lacking posthumeral foveae, elytron with 8 entirely punctate interneurs. ABL = 1.84–3.04 mm. (
Species of this subgenus are restricted to the New World, described from México south to Argentina and some of the Caribbean islands.
Both species of the Meotachys subgenus Hylotachys described above are the first “bifoveate’ (
Previously synonymized under Polyderis (
Nototachys Alluaud, 1930 is a small but distinctive group whose name has been considered a subjective synonym of Elaphropus (Erwin 1974) or the Elaphropus subgenus Sphaerotachys (
Relationships among groups within the subtribe Tachyina, in particular Elaphropus, remain a subject of contention and have been reviewed by several authors in recent decades. The conflicting taxonomic concepts proposed in previous reviews, classifications, and checklists (
Due to their small size and a lack of resources for their identification, tachyines are easy to overlook or misidentify. A good deal of undescribed tachyine diversity is likely hidden in uncurated material, stored bycatch, and existing collections (
In addition to the individuals mentioned under Material examined above, the authors thank all the collectors and curators who provided specimens for this work: George Ball (