Hydrodessus

Notice:

This page is derived from the original publication listed below, whose author(s) should always be credited. Further contributors may edit and improve the content of this page and, consequently, need to be credited as well (see page history). Any assessment of factual correctness requires a careful review of the original article as well as of subsequent contributions. If you are uncertain whether your planned contribution is correct or not, we suggest that you use the associated discussion page instead of editing the page directly. This page should be cited as follows (rationale): Miller K (2016) Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini). ZooKeys (580) : 45–124, doi. Versioned wiki page: 2016-04-12, version 90751, https://species-id.net/w/index.php?title=Hydrodessus&oldid=90751 , contributors (alphabetical order): Pensoft Publishers. Citation formats to copy and paste BibTeX: @article{Miller2016ZooKeys, author = {Miller, Kelly B.}, journal = {ZooKeys}, publisher = {Pensoft Publishers}, title = {Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini)}, year = {2016}, volume = {}, issue = {580}, pages = {45--124}, doi = {10.3897/zookeys.580.8153}, url = {http://zookeys.pensoft.net/articles.php?id=8153}, note = {Versioned wiki page: 2016-04-12, version 90751, https://species-id.net/w/index.php?title=Hydrodessus&oldid=90751 , contributors (alphabetical order): Pensoft Publishers.} } RIS/ Endnote: TY - JOUR T1 - Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini) A1 - Miller K Y1 - 2016 JF - ZooKeys JA - VL - IS - 580 UR - http://dx.doi.org/10.3897/zookeys.580.8153 SP - 45 EP - 124 PB - Pensoft Publishers M1 - Versioned wiki page: 2016-04-12, version 90751, https://species-id.net/w/index.php?title=Hydrodessus&oldid=90751 , contributors (alphabetical order): Pensoft Publishers. M3 - doi:10.3897/zookeys.580.8153 Wikipedia/ Citizendium: <ref name="Miller2016ZooKeys">{{Citation | author = Miller K | title = Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini) | journal = ZooKeys | year = 2016 | volume = | issue = 580 | pages = 45--124 | pmid = | publisher = Pensoft Publishers | doi = 10.3897/zookeys.580.8153 | url = http://zookeys.pensoft.net/articles.php?id=8153 | pmc = | accessdate = 2025-03-06 }} Versioned wiki page: 2016-04-12, version 90751, https://species-id.net/w/index.php?title=Hydrodessus&oldid=90751 , contributors (alphabetical order): Pensoft Publishers.</ref> See also the citation download page at the journal.

Taxonavigation

Ordo: Coleoptera
Familia: Dytiscidae

Name

Hydrodessus J. Balfour-Browne, 1953 – Wikispecies link – Pensoft Profile

• Hydrodessus J. Balfour-Browne, 1953: 55 (type species: Hydrodessus siolii J.Balfour-Browne, 1953: 56 by original designation); Young 1967: 80, 83; 1969: 2; Biström 1988: 36; Nilsson 2001: 236, 2013: 214.
• Brinckius Guignot, 1957: 38 (type species: Brinckius biguttatus Guignot, 1957: 39 by original designation); Biström 1988: 37; Nilsson 2001: 236, 2013: 214; synonymy by Young 1969: 2.
• Brinkius, Young 1967: 80, 83; 1969: 2 (incorrect subsequent spelling).

Diagnosis

Hydrodessus are distinguishable from other Bidessini by the following combination: 1) the lateral lobes of the aedeagus comprised of a single segment (instead of two or three), 2) without basal pronotal striae, and 3) without prominent carinae on the disc of elytron and no large pores on dorsal and ventral surfaces. In addition, Hydrodessus do not have basal elytral striae, modifications to the anterior clypeal margin (except in one species), a transverse occipital line between the posterior margins of the eyes, nor a transverse carinae across the elytral epipleuron at the humeral angle.

Natural history

Relatively little is know of the natural history of most members of the group. A great many museum specimens were collected at lights. Other specimens were collected from forest streams, often in low numbers. Occasionally, longer series have been found in tropical forest streams. Larvae and other aspects of their natural history have not been described.

Taxonomic history

Hydrodessus has a complicated character combination, and because of this has had a history of ambiguous taxonomic placement. The genus was early placed in or near Bidessini, but not without reservation (Guignot 1957). Though Young (1967; 1969) classified it in Bidessini, Biström (1988) restricted the definition of that tribe to those Hydroporinae with bi- or trisegmented lateral lobes, which are single-segmented in Hydrodessus (and at least some Amarodytes (Benetti and Régil Cueto 2004)). Hydrodessus was subsequently placed incerta sedis with respect to tribe until Miller and Bergsten (2014) placed it back into Bidessini. This was based on a large phylogenetic analysis including many DNA sequence data and morphology which resulted in Hydrodessus together with Peschetius (previously placed in Bidessini by Miller et al. (2006)) and some Amarodytes in a clade, and this sister to other Bidessini. Miller et al. (2006) expanded the definition of Bidessini to include taxa with 1) a spermathecal spine, and 2) five lobes on the crusher teeth of the proventriculus, which resulted in Peschetius and Amarodytes included in the tribe, but Hydrodessus was not examined comprehensively at that time. Based on evidence gathered for this revision, at least some Hydrodessus have a spermathecal spine, though not all do, and some have five-lobed crusher teeth on the proventriculus, though not all were examined. Based on this, and on evidence from Miller and Bergsten (2014), the genus is recognized here in Bidessini, and related to Peschetius and (at least) some Amarodytes.
The first species of Hydrodessus, Hydrodessus siolii J. Balfour-Browne, was described along with the genus description (Balfour-Browne 1953). Subsequent to this, Guignot (1957) erected the new genus, Brinckius Guignot, with four new species. Spangler (1966) added two new species from Peru to Hydrodessus. In his treatment of the genera of New World Bidessini, Young (1967) was uncertain whether to synonymize Brinckius with Hydrodessus, though he keyed them out together. Nilsson (2001) regarded the synonymy of Brinckius with Hydrodessus to date to Young’s (1967) paper. However, Young (1967, 83) seemed to make it clear at that time that he could not “…decide… whether Brinkius [sic] of Guignot should be accorded recognition.” Even so, he soon (Young 1969) did synonymize Brinckius with Hydrodessus and provided a list of the included species. He then (Young 1970) added two more and provided a key to all the species. The next contribution was by Spangler (1985), who added five new species from Guyana and also provided a key to the species. Though not included in his concept of Bidessini, Biström (1988) listed the species. The last addition of species to the genus was three by Makhan (1994), bringing the total to 17 valid Hydrodessus species prior to this revision.
Monophyly of Hydrodessus as deliminated here has not been demonstrated, and all the known diagnostic features described here for the genus are plesiomorphies. Other distinctive characters (potential synapomorphies) are variable within the genus. Many species have a lateral carina on the elytron extending posteriorly from the humeral angle, but not all do, and some of those that do have it only weakly developed. Most also have longitudinal carinae on the metaventrite approximately continuous with the metacoxal lines, but not all do. These two characters are also not always in the same combinations. All species have a similar overall appearance, robust, laterally discontinuous between the pronotum and elytron, elongate, with a variety of color patterns, and a somewhat characteristic shape for the prosternal and metasternal processes, but these are not particularly convincing as synapomorphies. Future research should concentrate on carefully examining the monophyly of the group and its relationships with Amarodytes and Peschetius, and possibly some Hypodessus Guignot, as well. It seems likely that Hydrodessus may eventually need division into multiple genera.

Distribution

Hydrodessus are characteristic mainly of northern South America from Ecuador and Peru to Brazil. The greatest known density of species is from southern Venezuela to Suriname. There are a few species extending south to Paraguay.

Key to the species of Hydrodessus

Two species, Hydrodessus amazonensis and Hydrodessus nanayensis, are problematic since no specimens were examined (the types were not found). Hydrodessus nanayensis is included in the key since, based on previous work, it appears to be very similar to (if not identical with) Hydrodessus siolii. The other species, Hydrodessus amazonensis, is not easily keyed with the characters included here since many of the states important for the key are not described for that species. It is included in the species treatments, however, and the male genitalia are relatively distinctive and diagnostic.

Key to the species of Hydrodessus — K. Miller

1		Size very small (TL < 1.7 mm)     Hydrodessus morsus sp. n.
–		Size larger (TL > 2.0 mm)    2
2	(1)	Lateral elytral carina short (<1/4 elytral length) (Fig. 27B) or absent (Fig. 31B)    3
–		Lateral elytral carina long (≥1/4 elytral length) (Fig. 35B)    17
3	(2)	Basal half of elytron approximately concolorous on disc, without distinct maculae (Fig. 27A), at most with diffuse, poorly-defined fasciae, though apical half of elytron often with maculae (as in Fig. 20A)    4
–		Basal half of elytron with distinctive maculae or fasciae (e.g. Fig. 22A)    11
4	(3)	Dorsal and ventral surfaces nearly concolorous, without maculae, though color may vary somewhat in intensity across surfaces (as in Fig. 27A); carinae on metaventrite somewhat divergent posteriorly (as in Fig. 27C)    5
–		Dorsal and ventral surfaces red to red-brown, apical half of elytron with irregular, subtriangular maculae and apex of elytron pale orange to yellow, pronotum of many specimens lighter orange, lighter in color than elytron (as in Fig. 20A); carinae on metaventrite strongly divergent posteriorly (as in Fig. 20C)    7
5	(4)	Size larger (TL > 3.0 mm)     Hydrodessus pereirai (Guignot)
–		Size smaller (TL < 3.0 mm)    6
6	(5)	Size smaller (TL = 2.0 mm); dorsal and ventral surfaces yellow (Fig. 27A)     Hydrodessus palus sp. n.
–		Size larger (TL = 2.5 mm); dorsal and ventral surfaces red (Fig. 12A)     Hydrodessus brevis sp. n.
7	(4)	Eyes entire (Fig. 21A) or emarginate (Fig. 20A) in dorsal aspect; male and female body shape dimorphic, male apically evenly tapered, female shorter and apically broadly rounded (as in Fig. 20A)    8
–		Eyes entire; male and female similar in shape, both apically evenly tapered    9
8	(7)	Eyes entire in dorsal aspect (Fig. 20A); male median lobe in lateral aspect broadly curved, basal portion elongate triangular, apex sinuate (Fig. 20D); median lobe in ventral aspect bilaterally symmetrical, apically narrowly rounded (Fig. 20E); lateral lobe moderately broad (Fig. 20F)     Hydrodessus kurti sp. n.
–		Eyes emarginate in dorsal aspect (Fig. 21A); male median lobe in lateral aspect very broadly curved, basal portion very broadly triangular, apex somewhat sinuate (Fig. 21D); median lobe in ventral aspect bilaterally asymmetrical, apically broadly expanded and truncate (Fig. 21E); lateral lobe very broad (Fig. 21F)     Hydrodessus kylei sp. n.
9	(7)	Prosternal process with lateral margins subparallel, slightly concave, posteriorly broadly rounded (Fig. 32C); female with apicolateral margin of elytron developed into flange (as in Fig. 5B)     Hydrodessus spanus Spangler
–		Prosternal process anteriorly with prominent, lateral lobes, posteriorly distinctly tapered to rounded apex (as in Fig. 28C); female without apicolateral flange along margin of elytron    10
10	(9)	Male median lobe bilaterally symmetrical in ventral aspect, apex rounded (Fig. 28E)     Hydrodessus peloteretes Spangler
–		Male median lobe bilaterally asymmetrical in ventral aspect, apex obliquely truncate (Fig. 17E)     Hydrodessus imparilis sp. n.
11	(3)	Prosternal process very broad (length/width < 1.8), lateral margins rounded, and broadly concave medially (as in Fig. 22C); carinae on metaventrite prominent, extending posteriorly to posterior margin (as in Fig. 22C)    12
–		Prosternal process narrower (length/wdith > 2), lateral margins variable, subparallel to sinuate, narrowly longitudinally concave medially (as in Fig. 33C); cariane on metaventrite indistinct, not generally extending to posterior margin except as narrow impunctate area (as in Fig. 33C)    13
12	(11)	Prosternal process very broad, apically broadly subtruncate (Fig. 22C); lateral pronotal margins broadly curved, greatest width medially (Fig. 22A)     Hydrodessus laetus sp. n.
–		Prosternal process broad but elongate with lateral margins broadly rounded and apex acuminate (Fig. 30C); pronotal margins not broadly curved, greatest width posterior to middle (Fig. 30A)     Hydrodessus rattanae Makhan
13	(11)	Prosternal process anteriorly with prominent, laterally-projecting lobes, lateral carinae distinctly convergent to narrowed apex (Fig. 33C); metaventrite carinae slightly divergent posteriorly, area between carinae narrow, apices of carinae terminating slightly mediad of anterior apices of metacoxal lines (Fig. 33C)     Hydrodessus surinamensis Young
–		Prosternal process anteriorly without or with weak, laterally-projecting lobes, lateral carinae subparallel to rounded apex (as in Fig. 19C); metaventrite carinae strongly divergent posteriorly, area between carinae broad posteriorly, apices of carinae terminating near anterior apices of metacoxal lines (as in Fig. 19C)    14
14	(13)	Elytron with two large pale regions, one quadrate macula laterally at anterolateral margin and one subtriangular, subapical maculae (Fig. 19A); males and females dimorphic, female elytron with distinct subapical lateral lobe (Fig. 5)     Hydrodessus keithi sp. n.
–		Elytral maculae not consisting of two large pale regions, either consisting of complex fasciae (as in Fig. 16A) or with multiple maculae, irregular in shape (as in Fig. 31A); males and females not dimorphic with female elytron without subapical lateral lobe    15
15	(14)	Elytral pattern complex, fasciate (Fig. 16A); ventral surface evenly brown     Hydrodessus fasciatus sp. n.
–		Elytral pattern simpler, with maculae subbasally near suture and lateral margin, submedially from lateral margin to near suture, and apically (as in Fig. 31A); ventral surface testaceous or yellow    16
16	(15)	Prosternal process shallowly depressed medially (Fig. 31C); medial portion of metacoxae (between metacoxal lines) with shallow longitudinal channels which are unmargined (Fig. 31C); dorsal pattern maculate (Fig. 31A)     Hydrodessus siolii J. Balfour-Browne
–		Prosternal process deeply depressed medially; medial portion of metacoxae with distinct longitudinal channels which are margined; dorsal pattern fasciate (Fig. 3)     Hydrodessus nanayensis Spangler
17	(2)	Posterior apices of metaventrite carinae located well mediad of anterior apices of metacoxal lines (Fig. 9C)    18
–		Posterior apices of metaventrite carinae near anterior apices of metacoxal lines, at most slightly mediad, but generally metaventrite carinae and metacoxal lines approximately continuous (Fig. 35C)    20
18	(17)	Body elongate, slender (TL/GW = 2.3–2.4); apices of elytra together pointed and slightly, but distinctly dehiscent (Fig. 9A)     Hydrodessus biguttatus (Guignot)
–		Body elongate, but generally somewhat more robust (TL/GW = 2.1–2.3); apices of elytra rounded or broadly pointed but not dehiscent    19
19	(18)	Overall length longer (TL > 3.5 mm)     Hydrodessus bimaculatus sp. n.
–		Overall length shorter (TL < 3.5mm)     Hydrodessus disjunctus sp. n.
20	(17)	Lateral elytral carina extending nearly to elytral apex (Fig. 35B); pronotum with anterolateral margins strongly angulate in many specimens (Fig. 35A1)     Hydrodessus angularis Young
–		Lateral elytral carina not extending nearly to elytral apex (Fig. 18B), at most extending a little past half elytral length; pronotum with anterolateral angles evenly curved    21
21	(20)	Prosternal process relatively slender (length/width > 2), lateral margins abruptly narrowed medially (Fig. 18C)     Hydrodessus jethoeae Makhan
–		Prosternal process broad (length/width < 2), lateral margins not abruptly narrowed medially, instead process broad throughout length (Fig. 24C)    22
22	(21)	Metaventral platform strongly constricted, length of metaventral platform long compared with narrowest distance between carinae immediately posteriad to mesocoxae (length/width of constriction > 5, greatest width/width of constriction > 2.5) (Fig. 24C)    23
–		Metaventral platfrom not strongly constricted, length of metaventral platform shorter compared with narrowest distance between carinae immediately posteriad to mesocoxae (length/width of constriction < 5, greatest width/width of constriction < 2.5) (Fig. 14C)    26
23	(22)	With distinctive maculae on elytra subbasally, subapically, and apically, basal macula distinct, transverse, extending nearly to suture (Fig. 24A)     Hydrodessus maculatus sp. n.
–		With elytral maculae indistinct, if present, mainly limited to subapical and apical indistinct pale areas, subbasal area of elytra of some specimens with indistinct, vague pale area    24
24	(23)	Pro- and mesotibia slender, without subapical emargination along dorsal margin (Fig. 7B)     Hydrodessus tenuatus sp. n.
–		Pro- and mesotibia broad, with subapical emargination along dorsal margin (Fig. 7A)    25
25	(24)	Length > 3.0 mm     Hydrodessus latotibialis sp. n.
–		Length < 3.0 mm     Hydrodessus phyllisae Spangler
26	(22)	Metacoxal lines broadly divergent anteriorly, approximately continuous with metaventrite/ metacoxal suture (Fig. 14C)     Hydrodessus continuus sp. n.
–		Metacoxal lines divergent or not, but intersecting metaventrite/metacoxal suture at distinct angle (Fig. 13C)    27
27	(26)	Greatest width of pronotum relatively narrow with respect to greatest width across elytra (EW/PW > 1.3) (Fig. 13A); dorsal surface with moderately distinct, but shallow, longitudinal grooves, best observed with oblique lighting (Fig. 13A)     Hydrodessus concolorans sp. n.
–		Greatest width of pronotum relatively broad with respect to greatest width across elytra (EW/PW < 1.2) (Fig. 26A); dorsal surface without grooves (Fig. 26A)    28
28	(27)	Prosternal process anteriorly with distinctly projecting lateral lobes, abruptly constricted medially (Fig. 11C)     Hydrodessus brasiliensis (Guignot)
–		Prosternal process with lateral margins approximately continuously curved, without prominent lobes, not constricted (Fig. 26C)     Hydrodessus octospilus (Guignot)

Taxon Treatment

• Miller, K; 2016: Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini) ZooKeys, (580): 45-124. doi

Images

Figures 1–7. Hydrodessus species. 1 Hydrodessus keithi, left metathoracic leg, posterior aspect 2 Hydrodessus amazonensis, redrawn from Spangler (1966) A dorsal habitus B male median lobe, right lateral aspect C male right lateral lobe, right lateral aspect 3 Hydrodessus nanayensis, dorsal habitus, redrawn from Spangler (1966) 4 Hydrodessus pereirai A dorsal aspect B lateral aspect C prosternal process, mesoventrite, mesocoxae 5 Hydrodessus keithi, elytra, lateral aspect A male B female 6 Hydrodessus biguttatus, right metatrochanter and metafemur, anterior aspect 7 Hydrodessus, left protibia, anterior aspect A Hydrodessus phyllisae B Hydrodessus tenuatus. Scale bars = 1.0 mm for 4A, B only.  Figures 8–10. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 8 Hydrodessus angularis: A1 dorsal habitus of specimen with strongly angulate pronotum: A2 dorsal habitus of specimens with less angulate pronotum 9 Hydrodessus biguttatus 10 Hydrodessus bimaculatus. Scale bars = 1.0 mm for A and B only.  Figures 11–13. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 11 Hydrodessus brasiliensis 12 Hydrodessus brevis 13 Hydrodessus concolorans. Scale bars = 1.0 mm for A and B only.  Figures 14–16. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 14 Hydrodessus continuus 15 Hydrodessus disjunctus 16 Hydrodessus fasciatus. Scale bars = 1.0 mm for A and B only.  Figures 17–19. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 17 Hydrodessus imparilis 18 Hydrodessus jethoeae 19 Hydrodessus keithi A1 male A2 female. Scale bars = 1.0 mm for A and B only.  Figures 20–22. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 20 Hydrodessus kurti A1 male A2 female 21 Hydrodessus kylei A1 male A2 female 22 Hydrodessus laetus. Scale bars = 1.0 mm for A and B only.  Figures 23–25. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 23 Hydrodessus latotibialis 24 Hydrodessus maculatus 25 Hydrodessus morsus. Scale bars = 1.0 mm for A and B only.  Figures 26–28. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 26 Hydrodessus octospilus 27 Hydrodessus palus 28 Hydrodessus peloteretes. Scale bars = 1.0 mm for A and B only.  Figures 29–31. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 29 Hydrodessus phyllisae 30 Hydrodessus rattanae 31 Hydrodessus siolii. Scale bars = 1.0 mm for A and B only.  Figures 32–34. Hydrodessus species. A dorsal habitus B lateral habitus C ventral surfaces D male median lobe, right lateral aspect E male median lobe, ventral aspect F male right lateral lobe, right lateral aspect 32 Hydrodessus spanus 33 Hydrodessus surinamensis 34 Hydrodessus tenuatus. Scale bars = 1.0 mm for A and B only.  Figures 35–41. Hydrodessus species, female reproductive tract, ventral aspect. 35 Hydrodessus angularis 36 Hydrodessus concolorans 37 Hydrodessus keithi 38 Hydrodessus kylei 39 Hydrodessus laetus 40 Hydrodessus maculatus 41 Hydrodessus phyllisae.  Figures 42–47. Hydrodessus species, distributions.  Figures 48–51. Hydrodessus species, distributions.