Polynoncus juglans (Ratcliffe, 1978)

(Figures 35, 42)

Trox juglans Ratcliffe, 1978: 299 (original description)

Trox (Polynoncus) juglans: Scholtz 1982: 16 (catalogue) Polynoncus juglans: Scholtz 1986a: 362 (systematics); Scholtz 1990: 1442 (redescription); Moragues 2010: 76 (catalogue from Guianas); Zidek 2013: 12 (checklist); Zidek 2017: 102 (checklist); Hielkema and Hielkema 2019: 12 (checklist of the Guianas)

Type specimen examined (through detailed photographs). HOLOTYPE. (♂ INPA – Figure 42) First label [white, printed]: ‘ BRASIL: Amazonas / Reserva Ducke / 26 km. NE Manaus / IX-27-1977 / B.C. Ratcliffe’. Second label [red, Brett Ratcliffe’s handwriting]: ‘ HOLOTIPO / TROX JUGLANS / RATCLIFFE / HOLOTIPO’. Third label [white, typeset]: ‘COLEO 083’ (Figure 42d). Type locality: ‘Reserva Ducke’ [Adolfo Ducke Forest Reserve], Manaus, Amazonas, Brazil.

ALLOTYPE (♀ INPA). First label [white, printed]: ‘ BRASIL: Amazonas / Reserva Ducke / 26 km. NE Manaus / IX-27-1977 / B.C. Ratcliffe’. Second label [red, Brett Ratcliffe’s handwriting]: ‘ ALLOTIPO / TROX JUGLANS / RATCLIFFE / ALLOTIPO’. Third label [white, typeset]: ‘COLEO 084’.

PARATYPES (2 MZSP). First label [white, typeset]: ‘ BRASIL: Amazonas / Reserva Ducke / 26 km. NE Manaus / XI-1-1977 / B.C. Ratcliffe’. Second label [yellow, Brett Ratcliffe’s handwriting]: ‘ PARATIPO / TROX JUGLANS / RATCLIFFE / PARATIPO’ (1 MZSP). First label [white, typeset]: ‘ BRASIL: Amazonas / Reserva Ducke / 26 km. NE Manaus / III-3-1978 / B.C. Ratcliffe’. Second label [yellow, Brett Ratcliffe’s handwriting]: ‘ PARATIPO / TROX JUGLANS / RATCLIFFE / PARATIPO’ (1 MZSP).

Differential diagnosis. Polynoncus juglans is the smallest species of the genus (~ 7 mm) and clearly distinct from its congeners. It is most similar to P. furcillifer and P. vazdemelloi, but differs from both by having a pronounced lateral margin of the pronotum (bulbous shape) in front of the posterior angle (see Huchet and Costa-Silva 2018); median edges and tubercles of pronotum raised and distinctive; elytral tubercles raised and elongate. Also, the median lobe (aedeagus) of P. juglans has a broader apex (chalice shape – Figure 42c), while the apex is narrow and parallel in P. vazdemelloi and bifurcate in P. furcillifer. For additional details of description and differential diagnosis, see Ratcliffe (1978), Scholtz (1990), and Huchet and Costa-Silva (2018).

Geographic distribution. Polynoncus juglans is recorded in northern Brazil and French Guiana (Figure 35). It is the sole species of Polynoncus recorded north of the Amazonas River.

This species was described from the Amazon Basin (Manaus, Brazil). Later, Scholtz (1990) expanded the geographical distribution after examination of material from French Guiana (11 specimens) and north-eastern Brazil (based on one specimen from Rio Largo, Alagoas, housed in BMNH).

The specimen mentioned by Scholtz (1990) from ‘Rio Largo’ was examined and identified as P. furcillifer. The label ‘FRY 1905–100’ indicates that this specimen belongs to the Fry Collection, and the label with the number ‘57,482’ refers to a specimen collected in Theresópolis (Teresópolis, Rio de Janeiro, Brazil) by Henri Deyrolle (1827–1902) according to the Fry’s catalogue.

Examined non-type material (22 specimens). BRAZIL: Amazonas, Manaus, Adolpho Ducke Forest Reserve, 2.930°S, 59.975°W, 28 April–3 May 2013, F.Z. Vaz-de-Mello leg. (2♂ CEMT); Manaus, Dimona Farm, Biological Dynamics Project of Forest Fragments (PDBFF), 2.343°S, 60.129°W, 20 February 2005, pitfall trap with dung, M. Radtke leg. (2 CEMT); Manaus, Esteio Farm, Biological Dynamics Project of Forest Fragments (PDBFF), 2.416°S, 59.833°W, 2–28 July 2000, I. Quintero leg. (1 CEMT). FRENCH GUIANA: Cayenne, Macouria, Matiti, ZA Wayabo, 5.072°N, 52.616°W, 2014, FIT, J.L. Gluglaris leg. (1 CERPE); Macouria, Matiti, ZA Wayabo, 5.072°N, 52.616°W, 2014, FIT, J.L. Gluglaris leg. (1 IEXA); Macouria, Matiti, ZA Wayabo, 5.072°N, 52.616°W, 2014, FIT, J.L. Gluglaris leg. (7 CEMT); Roura, Trésor Regional Nature Reserve, 225 m, 4.610°N, 52.278°W, 29 November 2009, flight interceptation trap, Stéphane Brule leg. (1♀ BMNH). Sinnamary, Paracou, Paracou Field Station, October 2003, pitfall trap with meat, edge of the forest, F. Feer leg. (1♂ and 1 unsexed CEMT). Without specific locality, 10 November 2018, P. Dalens leg. (1♂ and 3 unsexed CVMD). GUYANA: East Berbice-Corentyne, Tigri, Oronoque and New River Heads, 1938, H. Beddington leg. (1 BMNH).