Amazonopsis cerdani Barr and Cerdan, 2021

Barr, Cheryl B., Cerdan, Axel, Clavier, Simon & Murienne, Jérôme, 2021, Amazonopsis cerdani (Coleoptera: Elmidae: Elminae), a New Species of Riffle Beetle from French Guiana with Habitat Observations, The Coleopterists Bulletin 75 (2), pp. 427-439 : 429-436

Amazonopsis cerdani Barr and Cerdan , new species

zoobank.org/ urn:lsid:zoobank.org:act:B274E2BD-5EE5-43B8-A404-99B5F6275D4E

( Figs. 1–7 )

Type Locality. French Guiana, tributary Crique Galfa SW of Régina, N 04.2876°, W 52.1725° .

Diagnoses. Males. Amazonopsis cerdani males ( Figs. 1 , 7 ) differ from those of A. theranyi and A. camachoi ( Barr 2018) most strikingly by the presence of stout, recurved spines on the ventral surface of protarsomeres 1–4 ( Fig. 1 ); the latter species have only setae, no spines. The morphology of the claws differs: the protarsal claws of A. cerdani ( Fig. 1A ) are unusually long and sickle-shaped, with the outer claw longer than the inner claw; A. theranyi likewise has the protarsal claws long and sickle-shaped, but the outer claw is slightly shorter than the inner claw; the protarsal claws of A. camachoi are short and stout, with the outer claw slightly longer and having an inner tooth about 1/3 the distance from the base. Ventral features ( Fig. 1B ): in A. cerdani the distance between the large, anterior prosternal teeth is wider than that of the labrum, whereas the distance between the smaller prosternal spines of the other two species is narrower than that of the labrum in A. theranyi and about the same as that of the labrum in A. camachoi . The posterior metaventral margin of A. cerdani is carinate with a pair of small teeth adjacent to the metacoxae; A. theranyi has a pair of adjacent, stout, tooth-like processes at the posteriomedial margin; A. camachoi has a pair of adjacent, flattened, lobe-like processes in the same position. The genitalia of A. cerdani ( Fig. 2 ) are distinctively different as well.

Females. Amazonopsis cerdani females ( Fig. 3 ) differ from those of A. theranyi ( Barr 2018) in the following characters: pronotum ( Fig. 3A ) with prominent median longitudinal sulcus and gibbosities (very humped in lateral view; Fig. 3C ) vs. pronotum with a faint, shallow sulcus and/or median longitudinal line and low swellings, if any; margins of pronotal perforations smooth and flat vs. margins uneven, granulate and raised; metaventrite ( Fig. 3B ) with two shallow depressions near posterior margin adjacent to the metacoxae vs. metaventrite convex near posterior margin. The female of A. camachoi is unknown. Males and females. Either sex of Amazonopsis cerdani ( Figs. 1 , 3 ) and A. theranyi ( Barr 2018) differ as follows: elytra with interval 2 widened and slightly raised at the base vs. elytra with interval 3 prominently convex; pronotum with arcuate lateral margins, widest in the middle and narrowest at the base vs. pronotum more parallel-sided, about the same width at the middle as at the base. Amazonopsis cerdani (4.32–4.68 mm long) is also a bit longer than A. theranyi (4.00– 4.25 mm long).

Description, Holotype Male. Length, 4.44 mm (excluding head); width, 1.88 mm. Cuticle mostly covered with pale, thin microreticulate plastron layer dorsally; with thicker, glossy, pale yellow plastron ventrally; cuticle shiny, dark red-brown where exposed, especially on elytra ( Figs. 1 , 7 ). Antenna: Red-brown, filiform.Antennomeres 1–10 each narrower at base than apex, antennomere 11 fusiform; antennomeres 1 and 2 each longer and stouter than 3–10, antennomeres 3 and 4 smallest, length of antennomeres 5–10 gradually increasing distally. Antennomeres 5–10 each with dense tuft of setae at apicoventral margin, overlapping base of next; antennomere 11 with marginal band of short setae extending 1/2 length of antennomere. Head: Black. Vertex, frons and clypeus covered with pale, microreticulate plastron and numerous, broad, flat, pale yellow setae associated with punctures of variable size. Vertex with two moderately large, elongate-oval protuberances on either side of midline, angled to form an anteriorly open “V”, inner margins carinate, base deeply excavated posteriorly, frons weakly convex; frontoclypeal suture straight, incised. Clypeus dark brown, anterior margin barely emarginate, setae slightly less dense than on vertex and frons. Labrum red-brown, barely emarginate, apicolateral angles broadly rounded; surface with small, evenly spaced punctures and short, fine setae; apical and lateral margins with fringe of pale, dense setae. Mandible with three closely appressed, short, rounded, apical teeth (not visible in the holotype specimen; described from another male from the type locality). Maxillary palpus yellow-brown; palpomere 4 elongate-oval, slightly flattened and curved, longer than 1–3 combined, with oval patch of sensillae at apex. Labial palpus yellow-brown; palpomere 3 longer than 1 and 2 combined, ovoid and moderately flattened, with oval patch of sensillae at apex. Pronotum: Length, 1.52 mm; width, 1.64 mm. Dark brown, covered with opaque, microreticulate plastron. Disc medially with shallow, closely spaced, small punctures; laterally punctures twice as large, deeper, irregularly spaced, lined with plastron and associated with very short, erect setae; anterolaterally and mediolaterally with broad, flat, scale-like, recumbent, pale yellow setae associated with large punctures (some setae apparently abrad- ed). In dorsal view ( Fig. 1A ), lateral margins coarsely granulate, unevenly arcuate; anterior margin trisinuate, strongly arcuate at middle; anterior angles acute, depressed; posterior angles barely acute; posterior margin trisinuate. Disc with weakly impressed, longitudinal sulcus, deepest at posterior margin, nearly obscure at apex; length about 3/4 that of pronotum. In lateral view ( Fig. 1C ), moderately convex; hypomeron ( Fig. 1B ) with large, deep, closely spaced punctures larger than lateral pronotal punctures; ventral margin with narrow, longitudinal band of pale yellow plastron. Scutellar shield flat, subcircular. Elytron: Length, 2.92 mm; width, 0.94 mm. Color dark red-brown, shiny, with remnants of pale, thin microreticulate plastron. Anterior margin with smooth, shiny, nearly glabrous band about 1 interval wide extending onto humeri; humerus with straight, broadly elevated margin; lateral margin smooth, slightly recurved with a narrow, longitudinal band of epipleural plastron dorsally visible; shallow sulcus about one interval wide adjacent to lateral margin extends from humeral angle to posterior 1/5 where it broadens near apex; elytra constricted at apical 1/5 at point of linkage with abdominal ventrite 4 lateral lobe; apex rounded, moderately produced. Disc with punctures striate, deep, coarse, lined with plastron; intervals of striae with fine, sparse setae; base of second elytral interval wider and more convex than other intervals. Epipleuron non-punctate, with glossy, golden-yellow plastron. Legs: Red-brown, sparsely setose; femora minutely and sparsely punctate, sparsely setose, covered by thin layer of shiny, pale plastron; tibiae with very thin layer of plastron, partly obscure perhaps due to abrasion; tarsi shiny, without plastron. Procoxa with microreticulate plastron; ventral face flat, densely covered with very broad, flat, scale-like setae; dense patch of long, fine, golden-yellow setae present on lateral face. Prothoracic leg with tibia longer than femur, tarsus shorter; profemur with oval patch of long, recumbent, golden-yellow setae on anterior surface from near base to 1/3 femoral length; protibia with pair of cleaning fringes, anterior fringe from base to 1/2 tibial length, posterior fringe from base to 1/3 length, more sparse. Protarsus with tarsomeres 1–4 each bearing a stout, recurved, ventral spine margined with a cluster of thick, yellow setae; spine of right tarsomere 2 longest, thick, hook-tipped (spine of left tarsomere 2 with tip broken off); spine of tarsomere 1 next longest, acute; spines of tarsomeres 3 and 4 much smaller, acute, spine of tarsomere 4 barely produced; tarsomere 5 longer than the others combined, ventral surface with sparse, short, pale yellow setae and a few longer, apical setae which barely extend over base of claws. Protarsal claws long, dissimilarly sickle-shaped, laterally flattened, sharply acute; outer claw longer; inner claw shorter, more strongly curved. Mesocoxa with microreticulate plastron; dense patch of long, fine, golden-yellow setae present on lateral face and adjacent mesoventral sclerites. Mesothoracic leg similar to prothoracic leg except mesofemur with elongate patch of long, recumbent golden-yellow setae on posterior surface extending from near base to more than 1/2 femoral length; mesotibia with pair of cleaning fringes, anterior fringe from base to less than 1/2 tibial length, posterior fringe from base to nearly 2/3 length. Mesotarsal claws dissimilarly sickle-shaped, much longer than protarsal claws, laterally flattened, sharply acute; right outer claw longer, slightly twisted (left outer claw partially broken off); inner claw 2/3 as long and about 1/2 as wide. Metacoxa medial surface concave with coarse, deep punctures; posterolateral surface with dense patch of long, golden-yellow setae. Metathoracic leg similar to other legs except longer; tibia longer than femur; single cleaning fringe on posterior face from base to about 2/3 tibial length; both claws slightly flattened but basically unmodified, stout, each longer than outer protarsal claw. Venter: Prosternum ( Fig. 1B ) covered with pale, microreticulate plastron; medially with broad, flat, yellow setae and large punctures; laterally with pale yellow plastron; disc concave; notosternal sutures abruptly carinate and angulate, each forming a large, ventrally direct- ed tooth near anterior margin; distance between teeth wider than that of labrum; pronotal hypomeron anterior margin curved and flanged, anterolateral margin with a small, nearly semicircular notch; prosternal process about twice as long as wide, shallowly sulcate and nearly parallel-sided between procoxae, apex broadly rounded, lateral margins elevated. Mesoventrite deeply, coarsely punctate; disc with pale, microreticulate plastron, mesepimeron and mesanepisternum with band of dense, pale yellow plastron. Metaventrite excavated at anterior margin between mesocoxae, excavation contiguous with that of mesoventrite; disc flat; discrimen narrowly sulcate; posterior margin adjacent to metacoxae carinate and produced, forming a small pair of teeth each bordered anteromedially by a moderately large depression; punctures oval, distinct, smaller medially, much larger and deeper laterally; disc with pale yellow plastron except where abraded along midline exposing shiny cuticle, most dense laterad and on metanepisternum. Abdomen with pale yellow plastron on all surfaces except for small patches of bare, shiny cuticle at midline; ventrites 1–3 non-setose, ventrite 4 with posterior fringe of sparse setae, ventrite 5 with fine, scattered setae and fringe at apical margin; punctures evenly spaced, not as large or dense as those on thoracic sternites, becoming progressively smaller with each succeeding ventrite; ventrites broadly convex, slightly flattened at midline; ventrite 5 apex slightly depressed. Genitalia: Elongate, moderately narrow ( Fig. 2 ). Phallobase longer than parameres, narrowest at basal 1/3. Paramere in dorsal ( Fig. 2A ) and ventral views ( Fig. 2C ) narrowest 2/3 distance from base; apex narrowly rounded, surpassing and clasping tip of penis, inner margin broadly arcuate, inner surface shallowly canaliculate; paramere in lateral view ( Fig. 2B ) narrowed slightly at middle, apical 1/4 expanded, paddle-like; tip broadly rounded and unpigmented. Penis shorter than parameres; base about as wide as paramere base, gradually tapered to pointed apex.

Description, Allotype Female. Length (excluding head), 4.44 mm; width, 1.92 mm; pronotal length, 1.40 mm; width, 1.64 mm; elytral length, 3.04 mm; width, 0.96 mm. Secondarily sexually dimorphic as follows, otherwise similar to the male ( Fig. 3 ). Pronotum: Disc ( Fig. 3A ) with two moderately large, median sublateral, elongate-oval perforations, margins glabrous, smooth and flat; two prominent gibbosities medial to perforations; disc depressed anterior to gibbosities; shallow, median longitudinal sulcus from basal 1/4 extending between gibbosities, then narrowing to barely discernable line extending to apical margin; two very shallow, round pits lateral to sulcus and posteromedial to perforations. In lateral view ( Fig. 3C ) pronotum distinctly gibbous, humpbacked in the middle. Legs: Protarsomeres and claws ( Figs. 3A–C ) normal, not enlarged or modified. Venter: Prosternum ( Fig. 3B ) lacking pair of teeth at anterior margin, prosternal process flat and weakly tapered between procoxae; metaventrite with two small, shallow depressions lateral to midline near posterior margin, posterior margin lacking teeth.

Variation. As described in Barr (2018), males and females of A. theranyi are secondarily sexually dimorphic, with males having unusual modifications of the protarsal and mesotarsal claws, the prosternum, and the metaventrite. Amazonopsis cerdani males likewise have similar modifications, and, in addition, have prominently spinose protarsomeres ( Fig. 1 ). Amazonopsis cerdani females lack these modifications as do female A. theranyi , but both species have a unique pair of deep perforations on the pronotal disc not present in the males ( Fig. 3A ). The following pronotal variations were observed among the males: pronotum with slight depressions visible in some individuals in the areas where perforations are located in females; pronotum with a shallow sulcus or simply a median longitudinal line ( Fig. 1A ). Among the females, pronotal variation is present in the size of the gibbosities, the depth of the median longitudinal sulcus, and whether or not the shallow, round pits posteromedial to the perforations are visible ( Figs. 3A, C ). Also, the prosternal process of males is narrower and more parallel-sided than that of females. Both sexes exhibit variation in the amount of plastron present vs. abraded from the cuticle. Females of A. cerdani from French Guiana are slightly larger than the males: males (n = 8) 4.40– 4.56 mm long, 1.88–1.96 mm wide; females (n = 8) 4.44–4.68 mm long, 1.92–2.00 mm wide. The non-paratype female from Peru is smaller, 4.32 mm long and 1.88 mm wide, than the eight female specimens from French Guiana.

Type Material. Holotype male deposited in MNHN, labeled: “ FRENCH GUIANA / tributary CriqUE GaLfa / SW Of RÉgina / 04.2876, −52.1725 / 11-XI-2017,A. Cerdan // HOLOTYPE / Amazonopsis cerdani / Barr & Cerdan” [red label, handwritten]. Allotype female deposited in MNHN, labeled: [as above] // “ALLOTYPE / Amazonopsis cerdani / Barr & Cerdan” [red label, handwritten]. Paratypes (18; 9 M, 9 F): “ FRENCH GUIANA / tributary Crique Galfa / SW Of RÉgina / 04.2876, −52.1725 / 11-XI-2017, A. Cerdan” (1 M, 1 F, ACC; 2 M, 3 F, EMEC; 1 M, 1 F, USNM); [as above] // “Voucher Number / CHY17-01- 07 / GenBank / accession number / MW488057” [right meso- and metathoracic legs removed for molecular analysis] (1 M, MNHN); [as above] // “Voucher Number / CHY17-01-06 / GenBank / accession number / MW488058” [right meso- and metathoracic legs removed for molecular analysis] (1 F, MNHN); “ FRENCH GUIANA / ca. 4.5 km SE Saül / Cr.[ique] NOUvELLE FrancE / 03.5972, −53.1779 / 9-XI-2016, C. B. Barr // Parc Amazonien / de Guyane at / Courant Doublé / coll.from leaf pack” (1 F, EMEC); “ FRENCH GUIANA / Montagne de Fer / 6 III 2019 86 m / Trib. tO CriqUE FLOrian / N5°17.85′ W53°31.47′ // WiLLiam D. / Shepard, leg. // Voucher Number / AME-2019 / GenBank / accession number / MW488059” [left legs removed for molecular analysis] (1 F, EMEC); “ FRENCH GUIANA / Crique Bois Bandé / Route de BÉLizOn / 04.2877, −52.5372 / 28-IX-2017,A. CErDan” (1 M, EMEC); “ FRENCH GUIANA / Courcibo River trib. / La Trinité Natl. [National] Nature / Res. [REsErvE], 4.4767, −53.2268 / 18/11/2019, S. CLaviEr // Voucher Number / COU19-AVC2AM-10” (2 M, 1 F, EMEC; 1 M MNHN) [1 M with left legs removed for future molecular analysis]. Paratypes also have the following final label: “PARATYPE / Amazonopsis cerdani / Barr & Cerdan” [yellow label, printed]. Other Material Examined: “ PERU: [Dpto.] Madre de Dios / Tambopata, Quebrada / Santo Rosario, el. 234 m / −12.87882, −69.73959 / 29-V-2012, T. Gonzales // collected from artificial / leaf pack of Inga edulis / leaves, ACEER-Stroud / project 2012-2013 // Amazonopsis cerdani ? / Barr & Cerdan / det. C. B. Barr” (1F, EMEC).

Larva. Despite recent research on the elmid larvae of French Guiana by Shepard et al. (2020), the larva of Amazonopsis remains unknown.

Etymology. This species is named in honor of Philippe Cerdan, the late father of coauthor AC, who was known as one of the adventurous entomologists of French Guiana. His “ joie de vivre ” is missed by all who knew him.

Distribution. Amazonopsis cerdani is known from French Guiana ( Fig. 4 ) and Peru, South America. The record from Peru is of a female and should be considered uncertain in the absence of an associated male. The five collection localities within French Guiana are all from different watersheds indicating that the species is widespread there.

Habitat. Crique Galfa tributary (N 04.2876°, W 52.1725°), the type locality ( Fig. 4 ), is a very small stream (mean width 2.54 m, mean depth 17.8 cm) in the Approuague River watershed at an elevation of 28 m. The water is slightly tannin-stained, and the current is mostly very slow (<5 cm /s) with some faster areas (5–25 cm /s). The sampling site is completely shaded by the canopy, but upstream the creek crosses some open agricultural areas. The stream bed is mostly composed of sand and gravel with patches of leaf litter, and the banks have patches of roots from the riparian vegetation. The A. cerdani specimens were found in leaf packs.

Crique Bois Bandé (N 04.2877°, W 52.5372°) is a tributary of the Comté River in the Mahury River watershed ( Fig. 4 ). At the collection site, at about 60 m elevation, the small stream (mean width 4.2 m, mean depth 36 cm) has a bottom substrate composed of sand, gravel, and some patches of pebble/stone, as well as patches of leaf litter and roots at the banks. The specimen of A. cerdani was found among the litter. The current is mostly slow (<5 cm /s) to moderate (5–25 cm /s) at log jam constrictions. The stream is impacted by gold mining, which contributes suspended silts giving the water a milky appearance and, upon settling out, partially clog the mineral and organic substrates.At the sampling site the stream is completely shaded by canopy; however, it is likely exposed upstream at the mine site. Water quality measurements taken at the time of sampling were as follows: water temperature 24.8 °C, pH 6.9, dissolved oxygen 7.5 mg /L (92.3%), conductivity 30.3 µS/cm, and turbidity 8.4 NTU.

Crique Florian tributary (N 05.2975°, W 53.5245°) ( Figs. 4, 5 ), in the Iracoubo River watershed, is a very small, shallow stream with a sandy-silty substrate, slow to moderate current, and tannin-stained water.At the sampling site, elevation about 90 m, the channel is clogged with logs and aquatic macrophytes, and the canopy is closed. A single A. cerdani specimen was collected from a leaf and stick pack.

The upper Courcibo River tributary (N 04.4767°, W 53.2268°) ( Figs. 4, 6 ) is in the Sinnamary River watershed at elevation of about 91 m. The stream is very small (1 m wide), shallow (20 cm deep), quasi-closed canopy, and has a large number of aquatic macrophytes ( Thurnia sphaerocephala (Rudge) Hook.f. ; Thurniaceae ). The substrate is sandy-silty, the current very slow (<5 cm /s), and the water very clear.Water quality measurements at the time of sampling were as follows: water temperature 24.8 °C, pH 6.25, dissolved oxygen 6.84 mg /L (82.2%), conductivity 19.7 µS/cm, and turbidity 0.13 NTU. Located in the La Trinité National Nature Reserve, the drainage area of the stream contains tropical rainforest without any anthropogenic disturbance and is representative of pristine (reference) conditions.

Amazonopsis was recognized in the field by author SC at the Courcibo River tributary; therefore, the specific microhabitat of A. cerdani could be verified ( Figs. 6, 7 ). The specimens were collected in leaf packs near the water surface in depositional areas with very slow current (<5 cm /s). No specimens of Amazonopsis were found in the downstream section of the tributary near the confluence with the Courcibo River despite intensive searching. The absence of macrophytes and the open canopy conditions downstream, in comparison to the upstream section, may be linked to the absence of the species.

A detailed description of Crique Nouvelle France (N 03.5972°, W 53.1779°) ( Fig. 4 ), a jungle stream in the watershed of the Maroni River, is found in Barr (2018). In summary, the small, shallow stream, at an elevation of about 210 m, has a mostly sandy substrate and tannin-stained water. Logs, branches and leaves (submerged and partially submerged) litter the channel. One specimen was collected from leaf packs or other woody debris.

Associated Taxa. Aquatic byrrhoid beetles collected at any of the same localities as Amazonopsis cerdani include: Austrolimnius Carter and Zeck , Cylloepus Erichson , Gyrelmis brunnea Hinton , Gyrelmis nubila Hinton , Gyrelmis simplex Hinton , Gyrelmis spinata Hinton , Gyrelmis thoracica Hinton , Heterelmis Sharp , Hexacylloepus heterelmoides Hinton , Hintonelmis delevei Hinton , Hintonelmis perfecta (Grouvelle) , Macrelmis tereus (Hinton) , Neoelmis Musgrave , Neolimnius palpalis Hinton , Pilielmis apama Hinton , Phanocerus Sharp , Stegoelmis prob. shepardi Fernandes, Passos and Hamada, Tyletelmis mila Hinton , Xenelmis Hinton ( Elmidae ); undescribed genus/species ( Protelmidae ); Dryops Oliver , Elmoparnus collinsae Spangler and Steiner , Platyparnus bollowi (Hinton) , Platyparnus frater (Hinton) ( Dryopidae ); Lutrochus Erichson ( Lutrochidae ).

KEY TO THE SPECIES OF ADULT MALE AMAZONOPSIS

1. Protarsomeres 1–4 with distinct spines ( Fig. 1 ) ..................... A. cerdani Barr and Cerdan, new species

1′. PrOtarsOmErEs 1–4 witHOUt spinEs..............2

2. Protarsomere 5 with two apical clusters of long, thick, curved setae; protarsal claws short and stout, not sickle-shaped, outer claw with a median tooth .......... A. camachoi Barr

2′. PrOtarsOmErE 5 witHOUt LOng, cUrvED apicaL setae; protarsal claws long and sickle-shaped, outer claw without a median tooth ................. ........................................... A. theranyi Barr

Figures

Fig. 1. Amazonopsis cerdani, new species, male habitus; 4.52 mm long, 2.00 mm wide. A) Dorsal view, B) Ventral view, C) Lateral view.

Fig. 2. Amazonopsis cerdani, new species, male genitalia. A) Dorsal view, B) Lateral view, C) Ventral view. Scale bar = 0.2 mm.

Fig. 3. Amazonopsis cerdani, new species, female habitus; 4.52 mm long, 1.96 mm wide. A) Dorsal view, B) Ventral view, C) Lateral view.

Figs. 4–7. Distribution and habitat of Amazonopsis cerdani, new species. 4) Distribution in French Guiana (1: Crique Nouvelle France; 2: Crique Florian tributary; 3: Crique Bois Bandé; 4: Crique Galfa tributary; 5: Courcibo River tributary); 5) Stream habitat; Crique Florian tributary, Montagne de Fer; 6) Submerged leafy debris microhabitat; Courcibo River tributary, La Trinité National Nature Reserve; 7) Live male on leaf.