Research Article |
Corresponding author: Stephen M. Baca ( baca@ku.edu ) Academic editor: Mariano Michat
© 2021 Stephen M. Baca, Andrew Edward Z. Short.
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:
Baca SM, Short AEZ (2021) Review of the New World Notomicrus Sharp (Coleoptera, Noteridae) I: Circumscription of species groups and review of the josiahi group with description of a new species from Brazil. ZooKeys 1025: 177-201. https://doi.org/10.3897/zookeys.1025.60442
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The New World species of the minute aquatic beetle genus Notomicrus Sharp compose a much greater diversity than their Old World congeners, with 14 of the 17 known Notomicrus species occurring in the Neotropics. A recent phylogenetic study recovered four primary New World species groups and found that there are a number of undescribed species across all of these main lineages. Here, we provide a taxonomic key to these New World species groups, including two described species that we currently do not place in any group (“incertae sedis” species), complete with images and illustrations of diagnostic characters and taxonomic notes including a list of known species in each group. This work provides a scaffold for further planned taxonomic revisions within the genus. In addition, we review the first of the four New World groups, the josiahi species group and describe one new taxon, N. interstinctus sp. nov. from northern Brazil. Provided are descriptions, habitus images and illustrations of diagnostic characters.
Aquatic beetles, Brazil, new species, South America, taxonomy
Notomicrus Sharp is the most speciose genus of the minute aquatic beetle subfamily Notomicrinae (Coleoptera: Noteridae). Its distribution spans Indomalaya, Oceania and the New World, though the majority of Notomicrus diversity occurs in the Neotropics (14 of 17 described species). Notomicrus species occupy a wide range of habitats, including the margins of ponds, streams, marshes and swamps, drying stream beds, forest pools, hygropetric habitats and terrestrial leaf litter. Some species present a high specificity in their habitat preference, while others are found to be more generalists (
Since its establishment by
The monophyly of Notomicrus has been previously supported, with the Old and New World clades each also being found to represent reciprocally monophyletic lineages (
The species-level phylogenetic reconstruction of
Here, we (1) diagnose and provide a taxonomic key to the four primary species groups of New World Notomicrus. As part of this objective, we review morphological characters of importance, illustrate diagnostic characters and provide habitus images of exemplar species, taxonomic notes and a list of known species and references for each group. We then (2) present the first of four species-level revisionary works of New World Notomicrus by reviewing the josiahi species group. Included are a diagnosis of the group, a re-description of N. josiahi Miller, 2013 and a description of a new species from Brazil.
Specimens were observed and measured using an Olympus SZX7 stereomicroscope. The microscope was equipped with 10× eyepieces, a DF PL 2×-4 objective (16–112× magnification) and a calibrated ocular micrometer. Genitalia and tarsal claws were relaxed in hot water and dissected. Dissections were placed in glycerine on glass slides for observation. For additional observations and images of the prosternal process, aedeagi and tarsal claws, selected specimens were cleared in a warm 10% potassium hydroxide (KOH) solution and periodically checked multiple times an hour. Once desired elimination of soft tissue was achieved, specimens were thoroughly rinsed in DI (deionized) water. In some cases, DNA voucher specimens were used for observation and imaging of structures as the lysing process also dissolves soft tissue, effectively clearing the specimen and negating the need to damage additional specimens.
Dorsal habitus images were obtained with a Visionary Digital microphotography system equipped with an Infinity K2 microscope using a 5× objective and Helicon Focus imaging software. Photos were aligned and stacked using CombineZP (www.hadleyweb.pwp.blueyonder.co.uk) and refined in Adobe Photoshop. Ventral images and images of structures to be used for illustrations were taken with an Olympus DP72 camera system attached to either an Olympus SZX16 stereomicroscope with an SDF PLAPO 1×PF or 2×PF objective or an Olympus BX51 compound microscope with an UPlanFLN 40× oil immersion objective. The digital images were then stacked as above, with structures traced using Adobe Illustrator. Prolegs, prosterna, noterid platforms and male genitalia were imaged with the aforementioned stereomicroscope imagining system; illustrations were traced from these images. Male genitalia were placed in a depression slide with a drop of KY jelly and the remainder of the depression was filled with ethanol (EtOH). The KY jelly maintains its viscosity so that genitalia will hold its position for imaging. The EtOH eliminates obscuring refraction. Tarsal claws were imaged on the compound microscope. The fifth (V) pro- and metatarsomeres with tarsal claws were placed on a flat slide with EtOH and a cover slip was applied and glycerine was then used the seal the outside of the slip. The lower surface tension of the EtOH allows the cover slip to press on the claws, flattening them against the slide.
Descriptive terminology follows previous works (e.g.
Noterid platform. In Notomicrus, the noterid platform is formed by the raised projections of the inner metacoxal lamellae.
Genitalia and appendages. Following
MIZA Museo del Instituto de Zoología Agrícola, Maracay, Venezuela (L. Joly);
SEMC Snow Entomological Collection, University of Kansas, Lawrence, KS (A. Short);
Size. The total body length of Notomicrus species ranges between ca. 1.0 mm and 1.8 mm. Following
Color. Most species of Notomicrus present dorsal coloration as varying shades from brown to yellow. However, individuals of some species present specific color patterns among sclerites. For example, some species appear bicolorous, with the elytra and head darker brown and contrasting against a lighter colored pronotum, for example, N. traili Sharp, 1882 (Fig.
Punctation. Elytral punctation can be very helpful in diagnosing species of Notomicrus. Many species differ in the relative coarseness, density and patterns of punctation. Punctation should be used in combination with other characters to diagnose species as this character often presents similarly across multiple species.
Microsculpture. External microsculpture in Notomicrus varies among species and, in combination with other characters, can be helpful for diagnosis. In Notomicrus, the microsculpture consists of a microreticulation, where a superficially impressed mesh of very fine lines or grooves creates small cells. This is usually present on most external sclerites of the head, thorax, abdomen and legs, though it may not be uniform across these sclerites in an individual (e.g. the microsculpture of the noterid platform often differs from that of the elytra). In particular, the degree of impression and size or density of the meshes can be characteristic for a species or group of species.
Eye size. The size of the eyes, relative to the head capsule, can be very useful in identifying species. Here, the relative eye size is presented as a ratio of the greatest width of the head (HW) and interocular distance (EW). Measurements are taken from dorsal aspect, approximately at posterolateral margins of the eyes. Interocular distance is taken from the narrowest point between the eyes. The larger the eyes relative to the head capsule, the larger the ratio HW/EW, for example, N. josiahi HW/EW = 2.35–2.53, N. petrareptans Baca & Short, 2018 HW/EW = 1.65–1.73.
Prosternal process. The shape of the prosternal process was observed to be variable among some species and species groups of Notomicrus (Fig.
Tarsal claws. The pro- and mesotarsal claws of males of Notomicrus show significant interspecific variation in size and shape. Following
Aedeagus. The aedeagus is especially helpful for diagnosing species. The median lobe should be observed from several angles as it tends to be asymmetric and an oblique orientation can give the appearance of a different shape. Despite relative reliability, the aedeagus is still best used in combination with other characters for identification. Many species, even those across species groups, can present very similar aedeagi. For example, the aedeagus of N. interstinctus sp. nov. (Fig.
N. brevicornis Sharp, 1882. Designation by Guignot 1946: 115.
(1) Eyes present; (2) metacoxae and metaventrite fused, suture indistinct laterad of noterid platform; (3) noterid platform not extending anteriorly on to metaventrite; (4) protibia with loose rows of spines and setae, lacking large spur at apex and tight comb of small spines on distolateral margin and not expanded distally beyond protarsal insertion; (5) partial fusion of metafurca and metacoxae, not forming complete ring; (6) mid-gular apodeme absent (
As noted by
This key is intended to be used as a first step in identifying New World species of Notomicrus. Identification of Notomicrus species can prove difficult for non-specialists, especially without additional species in hand for comparisons. Diagnoses of the species groups of Notomicrus also reflect this difficulty.
1 | Size small, TL = 1.3 mm. Elytral punctation almost entirely indistinct, except discal row and submargin of elytral suture with distinct punctures, with very fine scattered setose punctures near lateral margins; elytral surface with microreticulation consisting of round, isodiametric cells, somewhat scale-like in appearance. Head appendages short, antennomeres VI–X wider than long; apical palpomeres distinctly bifurcate with enlarged sensory fields. Aedeagus as in Fig. |
N. teramnus |
– | Size variable, ca. 1.2–1.9 mm. Elytral punctation and microsculpture variable. Antennomeres usually longer than wide; apical palpomeres variable. Median lobe of aedeagus without conspicuous hooks or large processes (e.g. Figs |
2 |
2 | Dorsal (outer) margin of protibia without notable robust seta at or near mid-length (Fig. |
josiahi group |
– | Dorsal margin of protibia with a robust seta at or near mid-length (often two in females), at least as long as most dorsal seta on dorsoapical angle (Fig. |
3 |
3 | Noterid platform with angles of posterior lobes squared or rounded (Fig. |
4 |
– | Noterid platform with angles posterior lobes acutely angled (as in Fig. |
5 |
4 | Elytral surface impunctate to weakly punctate, punctures usually inconspicuous and sporadic under normal magnification, except for discal series; microreticulation variably impressed, consisting of small, round, isodiametric cells, giving the appearance of small scales. Body form variable, but usually oblong, less attenuated posteriorly (Fig. |
nanulus group |
– | Punctation distinctly present and often dense on posterior half of elytra, punctures finely to moderately impressed, bearing short setae, often extending on to anterior half of elytra; microreticulation variably impressed, consisting of fine mesh-like reticulation. Body form variable, but more elongate and attenuated posteriorly (Fig. |
meizon group (in part) |
5 | Color uniformly brown. Elytral surface with microreticulation variably impressed, consisting of small, round, isodiametric cells, giving the appearance of fine scales, somewhat shiny, but never iridescent; punctation variable. Males with anterior protarsal claw bifurcate or branched (as in Fig. |
6 |
– | Color variable, uniform or bicolorous. Elytral surface with microreticulation variably impressed, consisting of fine mesh-like reticulation, sometimes iridescent. Males with protarsal claws never bifurcated or branched | 7 |
6 | Body form oblong, rounded posteriorly (as in Fig. |
N. brevicornis Sharp, 1882 |
– | Body form ovoid, more elongate, more attenuated posteriorly (as in Fig. J). Elytral surface weakly to moderately punctate. Median lobe different. Indomalaya and Oceania | tenellus group |
7 | Protibia with robust seta of dorsal margin distinctly distad of half-length of outer margin, approximately at 2/3 margin length (Fig. |
traili group |
– | Protibia with robust seta of dorsal margin approximately at half-length of outer margin, distance between robust seta and dorsoapical angle subequal to distance between robust seta and protibial insertion (Fig. |
meizon group (in part) |
The josiahi group is diagnosed by the following combination of characters. Dorsal (outer) margin of protibia without notable robust seta at or near mid-length (Fig.
Representative prolegs of Notomicrus species groups (left proleg, anterior aspect) a josiahi group (N. josiahi) b nanulus group (N. nanulus) c meizon group (Notomicrus sp.) d meizon group, alternative setal spacing of dorsal (outer) protibial margin (Notomicrus sp.) e traili group (N. cf. traili) f detail of structures of importance. F1Se = setae of anteroventral margin of profemur; F1Sp = protuberance of posteroventral margin of profemur; PtCA = anterior protarsal claw; Ptm-5 = protarsomere V; SeDA = first robust seta of dorsoapical angle; SeMl = robust seta at mid-length of anterodorsal margin of protibia; SeM = First seta of anterodorsal margin of protibia; arrows indicate points for relative lengths (see key): i = anteroapical angle, ii = robust seta at mid-length, iii = first seta of marginal row.
Notomicrus josiahi Miller, 2013: 244; Holotype: MIZA
Venezuela, Amazonas State, Communidad Caño Gato, Rio Sipapo, 4°58.838'N, 67°44.341'W.
Paratypes : “VENEZUELA: Amazonas State/ 4°58.845'N, 67°44.341'W, 100 m/ Communidad Caño Gato on Rio/ Sipapo; sandy stream; 7.i.2006; AS-06-016; leg. A.E.Z. Short” [White label, typed print] (1 female ex. SEMC); “VENEZUELA: Amazonas State/ 4°58.845'N, 67°44.341'W, 100 m/ Communidad Caño Gato on Rio/ Sipapo; 16.i.2009; leg. Short,/ Miller, Camacho, Joly, & Garcia/ VZ09-0116-01X; along stream” [White label, typed print] (1 male, 2 females ex. SEMC) All paratypes with white barcode label with the following numbers and “KUNHM-ENT”: “SM0843570” “SM0831496” “SM0842848” “SM0843672”; all paratypes with “PARATYPE/ Notomicrus josiahi/ Miller, 2013” [Blue label with black border, typed print].
Venezuela: Amazonas State, 4°58.845'N, 67°44.341'W, 100 m, Communidad Caño Gato on Rio Sipapo; 16.i.2009; leg. Short, Miller, Camacho, Joly, & Garcia/ VZ09-0116-01X; along stream (64 males and females ex. SEMC).
TL = 1.46–1.69 mm (mean = 1.59 mm, SD. = 0.058, males = 1.46–1.69 mm, male mean = 1.58, SD. = 0.069, females = 1.55–1.68 mm, female mean = 1.62, SD. = 0.036); TLPn = 1.33–1.53 mm (mean = 1.44, SD. = 0.045, males = 1.33–1.49 mm, females = 1.43–1.53 mm); GW = 0.68–0.78 mm (mean = 0.74 mm, St. Dev. = 0.025, males = 0.68–0.78 mm, females = 0.72–0.78 mm); HW = 0.40–0.45 mm (mean = 0.42 mm, SD. = 0.014, males = 0.40–0.43 mm, females = 0.42–0.45 mm); EW = 0.16–0.19 mm (mean = 0.175 mm, SD. = 0.01, males = 0.16–0.17 mm, females = 0.17–0.19 mm); TL/GW = 1.99–2.31 (mean = 2.16; SD = 0.070; males = 1.99–2.31, females = 2.13–2.22); HW/EW = 2.21–2.53 (mean = 2.39, SD = 0.083, males = 2.41–2.53, females = 2.21–2.44).
Representative noterid platforms of Notomicrus species groups (left side, ventral aspect). Names in boxes indicate species groups or species a N. josiahi b N. nanulus c N. sharpi d N. sp. (nr. chailliei) e N. nr. meizon f N. meizon (paratype) g N. nr. malkini h N. brevicornis (female syntype) i N. teramnus (female paratype) j N. tenellus (Indonesia) k N. sabrouxi (female paratype, sketched from
Notomicrus josiahi can be diagnosed by the following combination of characters: (1) Size large TL = 1.46–1.69 mm; (2) elytron with strongly darkened region in anterior 1/3rd, contrasting against brownish-yellow of rest of elytron (Fig.
Aedeagi of josiahi species group 6 N. josiahi 7 Notomicrus interstinctus sp. nov. a median lobe, left lateral aspect b median lobe, dorsal aspect c median lobe, right lateral aspect d left lateral lobe, medial surface/aspect e right lateral lobe, medial surface/aspect. Scale bars: 100 µm
Males. Body elongate-oval, attenuated posteriorly (Fig.
Color. Head, pronotum, venter and legs yellow; elytron dark brown to black in basal 1/3, darkened region extending posteriorly along elytral suture and contrasting against brownish-yellow color of posterior 2/3 of elytron (Fig.
Structures. Eyes very large relative to head capsule (HW/EW = 2.35–2.53); antennae with length greater than greatest width of head. Prosternal process narrow, not strongly constricted between procoxae, with apex attenuated (Fig.
Sculpture. Dorsal surface of head with microsculpture very weakly impressed, microreticulation very fine, meshes mostly indistinct; micropunctation nearly indistinct. Pronotum with microsculpture similar to that of head, microreticulation fine; with scattered punctation near base and lateral margin, lateral punctures moderately dense, some with very fine setae. Elytron with microsculpture weakly impressed, microreticulation very fine, nearly indistinct; with punctation sparse in anterior half, with fine punctures along lateral margin and along discal row, with very few to no punctures between discal row and elytral suture, punctate in posterior half, punctures fine, many with very fine setae; discal row composed of fine and irregularly scattered punctures, denser posteriorly, lateral row similar to discal row but more sparse; micropunctation present, evenly scattered. Noterid platform and metaventrite surface with microsculpture weakly to moderately impressed, very fine, meshes of microreticulation nearly indistinct, cells transversely elongated.
Aedeagus. Aedeagus as in Fig.
Females. As males, except eyes slightly smaller than in males (HW/EW females = 2.21–2.39); profemur with posteroventral margin smooth, lacking weak angle at mid-length; pro and mesotarsomeres unmodified, slender, lacking adhesive discs; pro and mesotarsal claws unmodified, claws of respective tarsi subequal in length, slender, weakly curved.
As this species is known from only a single series, it is difficult to assess the degree of intraspecific variation. However, some variation was observed in the relative lightness or darkness in coloration of the individuals, with some brighter in color, more yellow, and others darker in color, more brownish yellow. The darkened region of the elytra also varied somewhat, occupying 1/4 to greater than 1/3 of the basal region of the elytron.
Notomicrus josiahi is among the most easily distinguished species of Notomicrus by the combination of the large eyes, color pattern, shape of male protarsal claws and of male aedeagus. Superficially, N. josiahi is similar to some species of the N. meizon group in color, wherein N. meizon Guimarães & Ferreira-Jr, 2019, N. malkini Young, 1978 and other undescribed species are also darkened at the base of the elytra. However, in N. josiahi, this darkened area is better defined with the posterior border less oblique, thus expanding more completely over the humeral angles of the elytron. More distinctly, N. josiahi differs from these and other species by the much larger eyes and bifurcate protarsal claws (in males), which to date, has only been observed in N. interstinctus, N. brevicornis and the tenellus group. Among all other species of Notomicrus, the aedeagus of N. josiahi is distinct, with the right lateral lobe rounded and bearing a small tuft of setae at apex, rather than without setae, as in all other neotropical species.
This species has been collected from only a single locality, from the margins of a small, sandy stream (Fig.
Brazil: Amapá, Calcoene, 2.50019, -50.97712.
Holotype, male: “BRAZIL: Amapá: Calcoene/ 2.50019°, -50.97712°; 5 m/ Colcoene (1 km W) on BR-156/ 22.vii.2018; leg. Short; Marshy/ savannah; BR18-0722-01A” [White label, typed print] “HOLOTYPE/ Notomicrus/ interstinctus/ Baca & Short, 2020” [Red label, black border, typed print] (ex.
TL = 1.50–1.63 (Holotype = 1.50 mm, mean = 1.56 mm, SD. = 0.045, males 1.50–1.63 mm, females 1.50–1.63 mm); TLPn = 1.38–1.48 (Holotype = 1.40 mm, mean = 1.42 mm, SD = 0.039, males = 1.40–1.45 mm, females = 1.38–1.48 mm); GW = 0.72–0.80 mm (Holotype = 0.72 mm, mean = 0.75 mm, SD. = 0.027, males = 0.72 mm–0.76 mm, females = 0.73–0.80 mm; HW = 0.41–0.45 mm (Holotype = 0.41 mm, mean = 0.43 mm, SD. = 0.013, males = 0.41–0.42 mm, females = 0.42–0.45 mm); EW = 0.18–0.22 mm (Holotype = 0.18 mm, mean = 0.20 mm, SD. = 0.013, males = 0.18–0.19 mm, females = 0.19–0.22 mm), TL/GW = 1.99–2.26 (Holotype = 2.08, mean = 2.07, SD. = 0.074, males = 2.06–2.26, females = 1.98–2.11); HW/EW = 2.04–2.33 (Holotype = 2.28, mean = 2.19, SD. = 0.088, males = 2.16–2.33, females = 2.04–2.26)
Notomicrus interstinctus can be diagnosed by the following combination of characters: (1) Size large TL = 1.53–1.63 mm; (2) elytron dark with contrasting yellow band at mid-length, apices yellow (Fig.
Holotype. As described for N. josiahi, except the following. Size large, TL = 1.53 mm. Body very broad, elongate-oval, strongly attenuated posteriorly, TL/GW = 2.08; lateral outline of elytron evenly and gradually curved to apex from point of greatest width, as in Fig.
Color. Dorsal surface of head brown, lighter near clypeus; pronotum yellow; elytron dark, nearly black in anterior and posterior thirds, with lighter contrasting brownish-yellow transverse band near mid-length of elytron, elytral apex also lighter, brownish-yellow; elytron with surface moderately iridescent. Ventral surface of head and prosternum light brownish-yellow; rest of venter yellowish-brown; legs yellow.
Structures. Eyes large relative to head capsule (HW/EW = 2.28). Posterior lobes of noterid platform with angles acute, apices rounded (as in Figs
Sculpture. Elytron with punctation as described in N. josiahi, but denser overall and less restricted to posterior half, with punctures along lateral margin and puncture rows more widely distributed and denser.
Aedeagus. Aedeagus as in Fig.
Females. As males, except eyes slightly smaller (HW/EW = 2.04–2.16); profemur with posteroventral margin smooth, lacking weak angle at mid-length; pro- and mesotarsomeres unmodified, slender, lacking adhesive discs; pro- and mesotarsal claws unmodified, claws of respective tarsi subequal in length, slender, weakly curved.
The most notable variation was in size and color, with some specimens darker overall than others, with the yellow bands sometimes smaller.
Notomicrus interstinctus is easily distinguished by the combination of large eyes and elytral color pattern, darkened in anterior and posterior thirds with a yellow transverse band. This color pattern is unique among known species of Notomicrus. This species is also unusual in that it is one of the few known species (along with N. brevicornis, N. josiahi and members of the tenellus group), with males that present bifurcated anterior protarsal claws. The aedeagus, color pattern and more subtly the denser punctation, easily differentiates this species from N. josiahi. The aedeagus of N. interstinctus is similar to that of the N. traili group with the median lobe attenuated and the apex enlarged and bent in a left-dorsal direction, but other external characters, such as the color pattern, tarsal claws and large eyes, readily distinguish this species from the traili group. The elytral punctuation is somewhat similar to that of some members of the N. meizon group, being somewhat densely punctate posteriorly, with punctures fine, but the aforementioned combination of characters will differentiate N. interstinctus from these species as well.
Notomicrus interstinctus sp. nov. derives its name from the Latin adjective interstinctus, meaning checkered or variegated. This refers to the color pattern of the elytra of this species. It is treated as an adjective in the nominative singular.
Known from northern Brazil, Amazonas and Amapá states (Fig.
The species seems to be a generalist in terms of habitat, but seems to prefer vegetated environments. It was collected from a very shallow open marshy area (Fig.
Notomicrus interstinctus appears very similar to specimens misidentified as N. traili Sharp, 1882 by
Members of this species group are most easily identified by their (1) monotone brown elytral color (Fig.
Members of the N. nanulus group present a combination of characters that are variably shared with N. brevicornis, N. teramnus and the members N. tenellus group. This pattern, in tandem with our phylogenetic understanding, for example, tenellus group being sister to all other Notomicrus (
N. chailliei Manuel, 2015; N. femineus Manuel, 2015; N. huttoni Young, 1978; N. nanulus (LeConte, 1863); N. sharpi Balfour-Browne, 1939.
Future work on this group may prove difficult as many species are collected with high ratios of females to males. An example was N. femineus Manuel, 2015, in which extensive collecting yielded only females, raising the possibility of parthenogenetic reproduction. Personal observations indicate that multiple undescribed species are represented by females only. We note that females of this group can be especially difficult to distinguish and are often misidentified as N. brevicornis (see comments on N. brevicornis, below). Notomicrus teramnus is a potential member of this species group based on color, shape and microsculpture, but is treated separately in the key, pending further investigation (see insertae sedis species below).
Non-teneral specimens of this group tend to have the following combination of characters: (1) triangular pigmented area medially on the base of the elytra (Fig.
N. malkini Young, 1978; N. meizon Guimarães & Ferreira-Jr, 2019.
The meizon group is sometimes difficult to discern from the traili group, as the differences amongst diagnostic characters can be subtle. The darkened basal area of the elytra in the meizon group is helpful, but investigators may find great difficulty in diagnosing teneral members of this group, which often lack the pigmented triangular area on the elytra. It is important to note that this darkened area is truly pigmented, not just darker in appearance due to the folding of the wings under the elytra as often happens in lighter colored species (as in Fig.
Non-teneral specimens of this group tend to have the following combination of characters: (1) lacking triangular pigmented area on the medial base of the elytra (Fig.
N. gracilipes Sharp, 1882; N. petrareptans Baca & Short, 2018; N. reticulatus Sharp, 1882; N. sabrouxi Manuel, 2015; N. traili Sharp, 1882.
Species of the traili group are difficult to discern and constitute a widespread species complex (see
These species present characters combinations not found in other species groups. Both by presented character combination and even general gestalt, these are difficult to place with certainty. Molecular sequence data were unavailable for these species in the phylogenetic reconstruction of
Syntypes
: Male specimen on small rectangular card, “♂” is drawn around genitalia and other parts, prosternal process flanks the specimen. “Boa Sorta Nov./ Sahlberg 1850” [small rectangular label, handwritten], “Sharp Coll/ 1905-313” [small rectangular label, typed], “Notomicrus/ brevicornis Ind. typ./ D.S.” [small rectangular label, handwritten] “SYN/ TYPE” [small circular label with blue border, printed] (ex.
Notomicrus brevicornis would otherwise appear to be a member of the nanulus group by the aforementioned characters. However, it differs by the more acute posterior angles of the noterid platform, a character shared with members of the tenellus, josiahi and traili groups. The male syntype presents a bifurcate anterior protarsal claw (as in fig. 8A), a character shared by the josiahi and tenellus species groups. With the Old World and New World taxa being reciprocally monophyletic (
Based on observation of the single male of the syntype series, it is suspected that
Personal observations show that many members of the N. nanulus group are misidentified as N. brevicornis in collections. This is no doubt due to the superficial similarities of N. brevicornis to members of the nanulus group and scarcity of males in the nanulus group. With that, there are likely inaccuracies in literature with respect to records and distributions.
Notomicrus teramnus would also appear a member of the nanulus group, given the above-mentioned characters. An argument could be made that this is the case as it only appears to differ in the shape of the posterior lobes of the noterid platform being more angular than most species in the nanulus group. This species otherwise appears to lack characters that would unite it with other species groups, though this will require examination and/or phylogenetic investigation. We abstain from placing it as member of the nanulus group as N. teramnus is known only from a high elevation hygropetric habitat, which may present confounding morphological specialization. Aedeagal morphology is not here considered to be indicative of a particular placement, but the very unusual morphology of the aedeagus of N. teramnus (see
We are grateful for the assistance and support of many colleagues during fieldwork in Brazil, including Neusa Hamada (