Pseudorygmodus Hansen, 1999

FIKÁýEK, Martin & VONDRÁýEK, Dominik, 2014, A review of Pseudorygmodus (Coleoptera: Hydrophilidae), with notes on the classification of the Anacaenini and on distribution of genera endemic to southern South America, Acta Entomologica Musei Nationalis Pragae 54 (2), pp. 479-514 : 485-494

Genus Pseudorygmodus Hansen, 1999

Pseudorygmodus Hansen, 1999a: 143 . Pseudorygmodus: SHORT & FIKÁýEK (2013) : 737 (assigned to subfamily Rygmodinae ).

Type species. Cylorygmus flintispangleri Moroni, 1985 (original designation).

Diagnosis. Adult. Pseudorygmodus may be easily distinguished from all other hydrophilid genera by the combination of the following characters: (1) elytra with metallic sheen ( Figs 1–2, 5–6 ), (2) elytron without scutellar stria ( Fig. 24 ), (3) labrum exposed and well sclerotized ( Figs 3–4, 7 , 57–58 ), (4) antenna with 9 antennomeres ( Fig. 16 ), (5) antennal club loosely segmented ( Fig. 16 ), (6) gular sutures fused ( Figs 35–36 ), (7) prosternum very short with distinct transverse groove ( Figs 35, 37–38 ), (8) anapleural sutures present, dividing mesoventrite from other parts of mesothorax ( Figs 18 , 39, 41 ), (9) mesoventrite without distinct median elevation or projection ( Figs 39, 41 ), (10) ¿rst abdominal ventrite without median longitudinal carina ( Figs 25 , 30 ), (11) posterior margin of abdominal ventrite 5 without notch ( Fig. 26 ), (12) pro- and mesofemora densely pubescent in basal two thirds, but metafemur bare, (13) legs without swimming hairs on tibiae or tarsi, and (14) basal meso- and metatarsomere much shorter than tarsomere 2 ( Figs 27–28 ).

Adults of Pseudorygmodus keys out to the Anacaenini using the keys of HANSEN (1991), and to couplet 23 (containing Anacaenini , part of Rygmodinae and Hybogralius Orchymont, 1942 ) in the tribal key by SHORT & FIKÁýEK (2013). It may be distinguished from all genera of the Anacaenini except Horelophus (as well as from all Rygmodinae and Hybogralius ) by the reduced gula and fused gular sutures. In contrast to Horelophus , Pseudorygmodus has the pronotum narrowing anteriad (subquadrate in Horelophus ) and its prosternum is extremely short (very long in Horelophus ), and both genera also never live together ( Horelophus is endemic to New Zealand: FIKÁýEK et al. 2012).

Larva (based on SPANGLER 1979a). Pseudorygmodus is easy-to-recognize by the large ligula projecting much further than the labial palps ( Fig. 66 ) and frontal sulci not joining posteriad into the coronal sulcus ( Figs 62–63 ), both of which assign the larva to the subfamily Chaetarthriinae . Within Chaetarthriinae , it is most similar to Anacaena Thomson, 1859 (not to Crenitulus Winters, 1926 , for details see Internal phylogeny of Anacaenini below) by the presence of the nearly symmetrical nasale with ¿ve teeth, of which the medium one is lower than the remaining four ( Fig. 69 ). Pseudorygmodus is not co-occurring with any member of Anacaena in its range nor in the habitat it lives in, and its larva is hence easy-to-identify. In Chile, it may co-occur with larvae of Anticura (which differs by the short ligula, nasale bearing only two teeth and frontal sulci converging posteriad: SPANGLER 1979b, ARCHANGELSKY 1997) and possibly also Enochrus (Hugoscottia) (which differs by the short ligula, asymmetrical nasale with variable number of small teeth and frontal sulci converging posteriad: FERNÁNDEZ 1992).

Adult morphology. Body elongate, moderately convex. General coloration of dorsal surface dark brown to black, with greenish or bluish metallic sheen; ventral parts reddish brown to dark brown.

Head. Clypeus and frons with sparse punctation, each puncture bearing very short apically widened seta, trichobothria absent on frons and clypeus; frontoclypeal suture indistinct; clypeus covering bases of antennae anterior of eyes, slightly projecting anteriad sublaterally, shallowly concave on anterior margin, membrane between clypeus and labrum not or only very narrowly exposed. Eyes small, slightly protruding from outline of head, separated by 4–5× the width of one eye. Labrum largely exposed dorsally, only slightly retracted under clypeus at base, widest subbasally, narrowed basally and arcuately narrowing anteriad, shallowly bisinuate on anterior margin ( Fig. 13 ); dorsal surface with two long setae anterolaterally and a transverse row of long setae (trichobothria) inbetween ( Figs 57–58 ), ground punctation similar to that on clypeus; epipharynx with a lateral row of 4–5 stout setae on each side, median portion with two vertical rows of long cuticular spines and cone-shaped group of similar spines anteriorly, sublateral portion on each side with oval/circular porose ¿eld, basal portion with densely pubescent membranous cone. Mandibles ( Fig. 12 ) symmetrical, with distinct mandibular angle, mandibular apex bi¿d; mediodistal portion with a group of long cuticular projections, medioproximal portion with ¿ne setae, mola moderately large, bearing numerous backwards directed setae on median face. Maxilla ( Fig. 14 ) with a simple subtriangular cardo lacking trichobothria; basistipes triangular, bearing few stout setae (some of them with dough-nut socket); mediostipes rather vaguely delimited from lacinia, the latter membranous, bearing ¿ne hair-like setae mesally and few stouter and longer setae distally, distal portion of lacinia subdivided into dorsal and ventral lobe; galea short, rounded apically, with distal setae arranged into well-de¿ned rows; palpifer rather small, with few rather long setae; palpomeres 2–4 enlarged or not, sexually dimorphic or of the same morphology in both sexes ( Figs 49–52 ); base of palpomere 4 with a group of digitiform sensilla on dorsolateral surface ( Figs 14 (detail), 32–33). Labium ( Figs 15 , 35–36 ) with submentum slightly shorter and as wide as mentum, bearing sparsely arranged setae; mentum 1.0–1.3× as wide as long, with continually strongly convex anterior margin, its surface flat, without microsculpture, bearing a few large setae (many of those with dough-nut sockets), lateral margins with sparse rows of long setae; prementum subdivided into two membranous lobes bearing ¿ne long setae, palpifer vaguely sclerotized; labial palpus with three palpomeres, palpomere 1 minute, palpomere 2 subequal in length to palpomere 3; palpomere 2 with two long subapical setae; palpomere 3 with numerous small distal short setae and one digitiform sensillum. Antenna ( Figs 16 , 31 ) with 9 antennomeres, scapus subcylindrical, ca. 2× longer than pedicel, pedicel widest at midlength, bearing few pore-like sensilla and one tiny seta, antennomeres 3–5 rather long, their combined length ca. 1.5× longer than pedicel, cupula small, antennomeres 7–9 forming a distinct, loosely segmented and densely pubescent antennal club; antennomere 9 slightly longer than antennomere 7 and 8 each. Gula ( Figs 35–36 ) completely reduced posteriorly, with gular sutures confluent, extremely narrow to totally reduced anteriorly, tentorial pits closely aggregated or totally confluent. Temporae without distinct ridge arising from inner margin of each eye.

Prothorax. Pronotum weakly and evenly convex, subtrapezoid in shape, widest basally, narrowing anteriad, anterior corners strongly projecting; lateral margins not forming continuous curve with lateral margins of elytra, anterior margin deeply bisinuate, posterior margin weakly bisinuate; ground punctation sparse and rather ¿ne, trichobothria missing; complete anterior, lateral and posterior margins with ¿ne marginal bead ( Fig. 46 ). Hypomeron without distinctly de¿ned lateral glabrous portion, only the lateralmost portion without pubescence, median portion densely pubescent; border between pronotum and hypomeron with series of pits with dough-nut sockets, without distinctly projecting sensilla; hypomeral process large, triangular, rounded mesally. Prosternum ( Figs 21 , 35, 37–38 ) very short anterior to procoxae, ca. 0.3× as long as procoxal cavity, with transverse ridge at least submedially, anterior margin slightly projecting mesally, with irregularly serrate shape and series of long setae, prosternal process very narrow, concealed between procoxae. Coxal cavity closed internally, open posteriorly, coxal ¿ssure widely open and not distinguished from coxal cavity, notopleural suture distinct. Accessory ridge below posterior pronotal margin laterally obliterated, recognizable as short and indistict ‘transverse fold’. Profurca consisting of two widely separated projections directed posteromesally at base, bent laterad and slightly widened into narrowly asymmetrical apically.

Mesothorax. Scutellum ( Fig. 22 ) with ¿nely microsculptured median portion, bearing sparsely arranged setae; scutellar shield exposed, triangular, pointed posteriorly, slightly longer than wide, with a few ¿ne setae present on its surface. Elytron ( Fig. 24 ) elongate, evenly convex; sutural stria present, reaching ca. apical third to half of elytral length; elytral series more or less regular, formed of punctures of only slightly larger size and slightly more densely arranged than interval punctation; scutellary stria absent, not visible even in slide-mounted elytron; elytral trichobothria absent, punctures of elytral series and intervals each bearing a very short apically slightly widened seta; lateral edge with a narrow bead, straight; epipleuron moderately wide anteriorly, gradually narrowing posteriad, very narrow in posterior half of elytral length, but reaching elytral apex; lateral bare portion of epipleuron very narrow, divided from median pubescent portion by a ¿ne ridge with series of pit-like dough-nut sockets without projecting setae ( Figs 44–45 ); ventral surface without any elevated ridges, only with a narrow longitudinal ¿eld of ¿ne spines situated sublaterally between anterior fourth and midlength. Mesoventrite ( Figs 18 , 39, 41 ) distinctly divided from mesanepisternum by distinct anapleural suture; subtrapezoid in shape in anterior two thirds, widely extended laterad in posterior third, coxal lobes of lateral extensions rather small; mesoventrite only very slightly bulged mesally, without distinct protuberances or ridges, bearing very sparse pubescence, medially with few trichobothria; mesoventral process narrow. Mesanepisterna meeting only at anterior margin of mesothorax; anterior collar well-de¿ned, moderately wide; mesal portion of each mesanepisternum pubescent, large lateral portions bare. Mesepimeron with large ventral portion, not reaching anterior collar or mesanepisternum anteriorly, forming lateral margin of coxal cavity; its whole surface sparsely pubescent. Coxal cavities obliquely transverse, ca. 2.5× wider than long, very narrowly separated from each other by mesoventral and metaventral processes. Mesofurca ( Fig. 20 ) well-developed, consisting only of the basal portion, furcal arms absent; basal portions arising as two widely separate projections from posterior wall of coxal cavities, apically widened into lance-like extensions.

Metathorax. Metanotum weakly sclerotized, ca. 2.2× wider than long, with rather wide anterior membranous area, alacristae slightly diverging posteriad. Metaventrite ( Figs 40, 42 ) ca. 1.5× longer than mesoventrite, evenly convex, without de¿ned median portion, whole surface (except for a small posteromedian area) bearing more or less dense pubescence; metaventral process narrow, contacting mesoventral process; metacoxal process short but distinctly exposed. Postcoxal ridge very narrow but well-de¿ned, continuous medially. Metanepisternum ca. 4.5–6.0× longer than wide, oblique transverse strengthened anterior ridge present only laterally, mesally reaching anterior margin; whole surface pubescent. Metepimeron not exposed ventrally. Metafurca ( Fig. 23 ) rather large, Y-shaped; stalk grooved medially, without basal extensions; lateral arms rather long, with large anterobasal extensions, apical portions roundly plate-like. Hind wing ( Fig. 17 ) well developed, ca. 2× longer than elytron, venation well-developed in basal half, absent in distal half; anal lobe rather large, well-defned by anal notch; venation nearly identical as that of Horelophus walkeri (see FIKÁýEK et al. 2012), only with the following differences: RP very long, reaching subbasally; median spur longer; RP 3+4 pigmented near posterior margin.

Legs. Coxae – procoxae subglobular, narrowly transverse, pubescent ventrally; mesocoxae transverse, rather robust mesally, narrowly separated, ¿nely pubescent ventrally; metacoxae narrowly transverse, subrectangular in ventral view, sparsely pubescent on whole ventral surface. Trochanters with proximal parts concealed by coxae, distal subtriangular parts exposed ventrally, pubescent; meso- and metatrochanter projecting into a small wide spine posterodistally, not forming continuous curve with posterior face of femora, protrochanter without such spine. Femora attached to trochanters by their posteromesal (meso- and metafemora) or anteromesal (profemora) portions only, anteromesal (meso- and metafemora) or posteromesal bases (profemora) free, angulate; pro- and mesofemora densely pubescent in their basal 0.65, metafemora lacking such pubescence except on extremely anterobasal portion, most of their surface bearing sparsely arranged spine-like setae; tibial grooves not de¿ned or very slightly de¿ned (male of P.flintispangleri , Fig. 43 ). Tibiae slightly longer than femora, cylindrical, slightly widening distad; each tibia with several rather irregular series of spines, distal portion with a group of enlarged spines and two rather short but stout tibial spurs; protibia oblique distally, with 2–3 large closely associated spines subdistally on outer margin closely associated with the outermost series of spines. Tarsi ( Figs 27–28 ) with 5 tarsomeres, basal tarsomere short, shorter than tarsomeres 2–5 each, tarsomere 2 longest, slightly longer than tarsomere 5, tarsomeres 3–4 subequal in length. Ventral setae of all tarsomeres short, spine-like in both sexes; claws rather large, arcuate, bearing a sharp subbasal tooth ( Fig. 29 ), shape sexually dimorphic (in P. flintispangleri ) or identical in both sexes ( P. versicolor sp. nov.); empodium moderately large, bearing a pair of stout subapical setae.

Abdomen ( Figs 25 , 46, 48 ) with ¿ve exposed ventrites; ventrite 1 with moderately large bare coxal grooves, remaining portion more or less densely pubescent, median portion without longitudinal carina; ventrites 2–5 subequal in length, more or less densely pubescent on whole surface, posterior margin of ventrites 1–4 smooth, lateral margins of ventrites 1–5 with a narrow bead; posterior margin of ventrite 5 without median emargination or group of enlarged setae, ¿nely serrate with series of small spine-like setae; laterotergite 3 simple, dorsal portion not divided from ventral one by a ridge, bearing an area of goose-head-shaped cuticular projections, without any kind of organized stridulatory ¿le; tergites weakly sclerotized.

Genitalia. Male genitalia ( Figs 59–61 ). Aedeagus of simply trilobed type; parameres ca. as long as or indistinctly shorter than phallobase, bearing numerous pore-like sensilla in apical portion; median lobe ca. as long as parameres, with subtriangular apical part, basal apodemes rather long, gonopore large, well de¿ned, apical to subapical; phallobase symmetrical, rounded basally, without distinctly de¿ned manubrium. Sternite 9 widely tongue-like, with very short subbasal lateral struts. Sternite 8 crescent-like, smooth (i.e. not serrate) on posterior margin, densely pubescent, without anterior projection. Female genitalia examined only externally, with long peg-like gonocoxites 9 and gonostyli 9.

Figures

Figs 1–7. Habitus of the species of Pseudorygmodus Hansen, 1999. 1–3 – P.flintispangleri (Moroni, 1985), male from Magellanes: Fiordo Eyre (1 – dorsal, 2 – lateral, 3 – frontal); 4 – same species, female from PN Puyehue. 5–7 – P.versicolor sp. nov., female from PN Nahuelbuta, Estero Agua de los Gringos (5 – dorsal, 6 – lateral, 7 – frontal).

Figs. 18–29. Morphology of Pseudorygmodus versicolor sp. nov., slide-mounted male paratype. 18 – meso- and metathorax, ventral view; 19 – detail of metatrochanter; 20 – mesofurca; 21 – half of prothorax in ventral view; 22 – mesoscutellum, dorsal view; 23 – metafurca; 24 – elytron, ventral view; 25 – abdominal ventrites, ventral view; 26 – detail of posterior margin of abdominal ventrite 5; 27 – mesotarsus; 28 – metatarsus; 29 – protarsal claw. Not to scale.

Figs 49–61. Morphological details of adults of Pseudorygmodus Hansen, 1999. 49–52 – maxillary palpus, ventral view (49 – P.flintispangleri (Moroni, 1985), male; 50 – P.flintispangleri, female; 51 – P. versicolor sp. nov., male; 52 – P. versicolor, female). 53–56 – metatibia, ventral view (53 – P. flintispangleri, male; 54 – P.flintispangleri, female; 55 – P. versicolor, male; 56 – P. versicolor, female). 57–58 – labrum, dorsal view (57 – P.flintispangleri, 58 – P. versicolor). 59 – aedeagus of P. flintispangleri. 60–61 – male genitalia of P. versicolor (60 – aedeagus, 61 – sternite 9).

Figs 12–17. Pseudorygmodus versicolor sp. nov., slide-mounted male paratype: morphology of head appendages (12–16) and metathoracic wing (17). 12 – mandible, ventral view (detail = mandibular apex in ventromesal view); 13 – labrum, ventral view; 14 – maxilla, ventral view (detail = digitiform sensilla on base of palpomere 4); 15 – mentum and prementum, ventral view (detail = labial palp); 16 – antenna; 17 – wing.

Figs 30–38. Morphology of Pseudorygmodus Hansen, 1999, SEM micrographs. 30, 33, 35 – P. versicolor sp. nov.; 31–32, 34, 36–38 – P.flintispangleri (Moroni, 1985), male. 30 – ventral morphology; 31 – detail of antenna and male maxillary palpus, ventral view; 32 – maxillary palpomeres 3–4 in dorsal view, with digitiform sensilla; 33 – maxillary palpomere 4 in dorsal view, with digitiform sensilla; 34 – punctation of frons next to eyes; 35 – head and prothorax in ventral view; 36 – head in ventral view; 37–38 – prosternum.

Figs. 39–48. Ventral morphology of Pseudorygmodus Hansen, 1999, SEM micrographs. 39–40, 43–44, 46–47 – P. flintispangleri (Moroni,. 1985), male; 41–42, 45, 48 – P. versicolor sp. nov. 39, 41 – mesoventrite; 40, 42 – meso- and metaventrite; 43 – male metafemur and metatibia; 44–45 – detail of epipleuron; 46 – detail of pronotum; 47–48 – detail of abdominal ventrites.

Figs. 62–72.Larval morphology of Pseudorygmodus Hansen, 1999 and its comparison with other genera of Anacaenini. 62–69 – larval morphology of P.flintispangleri (Moroni, 1985) according to SPANGLER (1979a) (62 – general habitus; 63 – head in dorsal view; 64 – antenna; 65 – maxilla; 66 – labium, dorsal view; 67 – labium, ventral view; 68 – right mandible, dorsal view; 69 – detail of clypeolabrum). 70–72 – morphology of clypeolabrum of third instar larvae of other Anacaenini (70 – Anacaena sp. from the Czech Republic; 71 – Crenitis morata (Horn, 1890), redrawn from ARCHANGELSKY (1997); 72 – Anacaena suturalis (LeConte, 1866), redrawn from ARCHANGELSKY & FIKÁýEK 2004).