Microparnus pusillus (Hinton, 1939) Shepard, 2019

Shepard, William D., 2019, Microparnus Shepard (Coleoptera: Byrrhoidea: Dryopidae), a New Genus from French Guiana, The Coleopterists Bulletin 73 (1), pp. 62-66 : 63-66

Microparnus pusillus (Hinton, 1939) , new combination

( Figs. 1 –2)

Helichus pusillus Hinton 1939a: 431–433 .

Description. Hinton’ s (1939a) original description and illustrations (figs. 1–5) of H. pusillus , based on nine specimens, are adequate and will not be repeated here. However, Hinton only illustrated the male genitalia, so a more detailed description is provided here. Male genitalia: Aedeagus tubular, dorso-ventrally arched; 0.74 mm long, phallobase 0.4 mm long, parameres 0.38 mm long, median piece projecting slightly beyond parameres; parameres very slender, apex with apical point projecting ventrally; median piece fills space between parameres, apex acute. Male and female M. pusillus look the same externally.

Type Material. Type specimen, M, with the following labels: Type [white circle with red border, typed] // St. Laurent / x. ’37. F. Guyane [handwritten] // H. E. Hinton / collector [typed] // Brit. Mus. / 1939-399 [typed] // Helichus / pusillus / Hint. (handwritten on white rectangle with red left border) // H. E. Hinton. / collection / B. M. 1977-566 (typed) // barcode / NHMUK010580156. Paratypes: one M, seven F (Hinton 1939a). One paratype has the following labels: St. Laurent / X.’ 37 F. Guyan [handwritten, part of label cut off] // ♀ // P type [white rectangle with red left border, handwritten] / Helichus / pusillus / Hint. // H. E. Hinton / collection / B. M. 1977-566 [typed]. Four more paratypes with same labels. Another specimen with same labels but lacking sex label. Another specimen with same labels but with ³ label. Another specimen has just the locality label and the H. E. Hinton collection label. All specimens in NHM .

Type Locality. FRENCH GUIANA: St. Laurent du Maroni (Hinton 1939a) .

Etymology. Hinton (1939a) did not indicate the etymology. However, pusillus is Latin for “very little”, which describes the size of the adults in comparison to other dryopids. In his key, Hinton says “species very small.”

Additional Material Examined. 1M – FRENCH GUIANA / 8 km NNW of Saül / 10 XI 2016 156 m / Crique à l’ Est / (WDS-A-2051 on reverse) // William D. / Shepard , leg.; 1M – FRENCH GUIANA / ca. 5 km NNW Saül / Crique à l’ Est / 03.66383, -53.22193 / 10-XI-2016, C. B. Barr // Parc Amazonian / de Guyane; 1M, 3F – FRENCH GUIANA / 8 km NNW of Saül / 10 XI 2016 156 m / Crique à l’ Est // N3.66383° / W53.22193° // Douglas L. / Post, leg. 1F – FRENCH GUIANA / Toussait surb 2 / 9 XI 2015 / HYDRECO crew. All of these specimens, except the 64 collected. Crique à l’ Est is a shallow, clear, brownwater stream situated in a closed forest with very little sunlight reaching the stream. The substrate is a patchwork of mud and sand in pools and gravel and rocks in riffles, with an abundance of leaves and logs in the stream ( Figs. 3–4 ). The water chemistry data from the Crique Toussait sampling are: dissolved oxygen = 66.2% (5.23 mg /l); conductivity = 32 µS/cm; T = 27.3° C; pH = 5.83; and turbidity = 4.98 NTU. The habitat occupied by Microparnus is similar to that described for Guyanobius Spangler (Gustafson and Short 2010) and Belladessus Miller and Short (Miller and Short 2015), also from the Guiana Shield.

Co-occurring Byrrhoid Taxa. Dryopidae – Dryops , Elmoparnus collinsae Spangler and Steiner , Platyparnus frater (Hinton) ; Elmidae – Gyrelmis brunnea Hinton , Gyrelmis thoracica Hinton , Heterelmis Sharp , Hexacylloepus Hinton , Hintonelmis delevei Hinton , Hintonelmis perfecta (Grouvelle) , Neoelmis nelo Hinton , Phanocerus Sharp , Stegoelmis geayi (Grouvelle) , Stenhelmoides Grouvelle ; Lutrochidae – Lutrochus Erichson ; Protelmidae – undescribed genus.

UPDATED KEY TO THE GENERA OF NEOTROPICAL AQUATIC AND SEMIAQUATIC DRYOPIDAE

1. Body dorsally glabrous; lateral margin of elytra

interrupted near apex by a densely pubescent

depression .................... Elmoparnus Sharp

1 ʹ. Body dorsally pubescent or with plastron; Fig. 2. Microparnus pusillus , dorsal habitus of a lateral margin of elytra without densely purecently collected female specimen. bescent depression ................................ 2

2. Pronotum with complete sublateral carina/

sulcus on each side ............. Dryops Oliver HYDRECO specimen, are deposited in EMEC; the 2 ʹ. Pronotum without sublateral carinae/sulci or HYDRECO specimen is deposited in HYDRECO. with only short carinae/sulci ................... 3 Remarks. As previously stated in the generic 3. Pronotum with sublateral carinae/sulci only in diagnosis, the only other dryopids that might be basal 1/4 to 1/3 .................................... 8 confused with M. pusillus are various species of 3 ʹ. Pronotum without sublateral carinae/sulci .... Dryops . Both genera can co-occur in the same ......................................................... 4 streams (see below). 4. Aantenna with 13 antennomeres ................ The type specimen is a male, and the aedeagus .............................. Onopelmus Spangler was dissected and illustrated (Hinton 1939a, figs. 4 ʹ. Antenna with 9 or 11 antennomeres .......... 5 1–3). Christine Taylor (NHM) reports that “Sadly, I 5. Antenna with 9 antennomeres ................... cannot find the genitalia. There is no vial, and ............................... Guaranius Spangler nothing in the slide collection. There is, however, a 5 ʹ. Antenna with 11 antennomeres ............... 6 slightly whiter area on the card mount, which 6. Antennomere 2 enlarged and covering rest of suggests that the aedeagus may have once been antennomeres .............. Helichus Erichson glued there, but there is no visible glue residue 6 ʹ. Antennomere 2 may be enlarged but not there now.” covering rest of antennomeres ................ 7 Distribution and Habitat. Currently, M. pusillus 7. Antennomere 2 enlarged and covering antenis known only from French Guiana, but it likely nomeres 3 and 4 ............ Parygrus Erichson occurs in neighboring countries as well. Hinton did 7 ʹ. Antennomere 2 not enlarged ..................... not describe the habitat where his specimens were .............................. Pelonomus Erichson à l’ Est, looking downstream.

66 8. Length 6–10 mm; males with pro- and mes- paratypes. Rachael Diaz-Bastin (California Acadotarsi with tarsomere 2 wide, flattened; an- emy of Sciences, San Francisco, CA, USA) photennae with 11 antennomeres .................... tographed the recently collected female specimen. ................ Platyparnus Shepard and Barr

8 ʹ. Length 2–3 mm; males with tarsomeres not

wide and flattened; antennae with 10 anten- REFERENCES CITED

nomeres ................. Microparnus Shepard

Gustafson, G. T., and A. E. Z. Short. 2010. Revision of the Neotropical scavenger beetle genus Guyanobius Spangler ( Coleoptera : Hydrophilidae : Chae- DISCUSSION tarthrini). Aquatic Insects 32(4): 245–258.

Microparnus is the 14 th dryopid genus described Hinton, H. E. 1939a. Descriptions and figures of new South American Dryopidae (Coleoptera) . Annals from the Neotropics, making the Neotropical dry-

and Magazine of Natural History, Series 11 4: opid fauna the most diverse of all zoogeographic 430–439.

regions. This is true both for genera that are ter- Hinton, H. E. 1939b. On some new genera and species restrial as well as those that are aquatic or semi- of Neotropical Dryopoidea ( Coleoptera ). Transaquatic. In general, dryopids are more diverse in actions of the Royal Entomological Society of tropical areas, such as parts of the Neotropical, London 89(3): 23–46.

Ethiopian, and Oriental regions. Miller, K. R., and M. Garcia. 2011. Spanglerdessus shorti and Incomptodessus camachoi, new genera ACKNOWLEDGMENTS and species of Bidessini from Guyana and Venezuela ( Coleoptera : Dytiscidae: Hydroporinae). Zootaxa 2996: 49–56.

Collecting and export permits in French Guiana

Miller, K. B., and A. E. Z. Short. 2015. Belladessus were made available from the Collectivité Terri- Miller and Short ( Coleoptera : Dytiscidae: Hydrotoriale de Guyane according to the DIAG project porinae:Bidessini), a new genus for two new species (Convention N°APA-973-13). Hydreco Guyane, from northern South America: Parthenogenetic Office de l’ Eau de Guyane, Direction de l’ Envir- diving beetles? The Coleopterists Bulletin 69(3): onnement de l’ Aménagement et du Logement de 498–503.

Guyane, and Parc Amazonien de Guyane are Shepard , W. D., and C. B. Barr. 2018. Platyparnus , thanked for providing financial and technical sup- a new genus of Dryopidae from the Guiana port. Simon Clavier (HYDRECO Guyane) expertly Shield ( Coleoptera : Byrrhoidea, Dryopidae ). Aquatic Insects 39(2–3): 209–226. DOI: 10.1080/ organized and led the collecting trip and provided

01650424.2018.1450987.

logistical assistance; plus, he provided the water Sites , R. W. 2015. New taxa of Cryphocricinae (Heterchemistry data from the Toussaint sampling. Cheryl optera: Naucoridae) from the Guiana Shield: B. Barr and Douglas L. Post ( Fig. 4 ) helped col- Hygropetrocoris Sites , n. gen. and two new species lect specimens. Christine Taylor (NHM) answered of Ambrysus Stål. Zootaxa 4033(3): 427–438.

many questions, searched for the type genitalia, and

kindly provided photographs of the type specimen (Received 4 September 2018; accepted 2 January 2019. of H. pusillus and information on the labels of the Publication date 25 March 2019.)

Figures

Fig. 1. Microparnus pusillus, type specimen. Structure in the box is the last two abdominal ventrites that are broken off the specimen.

Figs. 3–4. 3) The author in Crique à l’Est, looking upstream; 4) Doug Post and Cheryl Barr collecting in Crique