Oosternum aequinoctiale ( Motschulsky, 1855 )

Hebauer, Martin Fiká Č Ek Franz & Hansen, Michael, 2009, Taxonomic revision of New World species of the genus Oosternum Sharp (Coleoptera: Hydrophilidae: Sphaeridiinae) I. Definition of species groups and revision of the Oosternum aequinoctiale group, Zootaxa 2054, pp. 1-37 : 16-24

Oosternum aequinoctiale ( Motschulsky, 1855)

( Figs. 32 , 36, 46, 56–57, 64, 70, 76, 79–80, 82, 84)

Cryptopleurus? aequinoctialis Motschulsky, 1855: 20

Crypteuna aequinoxialis ( Motschulsky) : Motschulsky (1863) Oosternum aequinoctialis (Motschulsky) : Hansen (1991)

Oosternum aequinoctiale (Motschulsky) : Hansen (1999a, b) Type locality: “ Panama ”

Type material: Lectotype (here designated): female ( ZMUM): “ Crypteuna aequinoxialis Motsch. Am. centr. Panama // Cryptopleurum aequinoctialis Motschulsky Lectotype, M. Hansen des. 1993”. Paralectotypes (here designated): 1 unsexed specimen ( ZMUC): “ C. aequinoxialis / Motsch. / N. America / Motschulsky // Mus / Westerm. // Cryptopleurum / aequinoctialis Motschulsky / PARALECTOTYPE / M. Hansen des. 1993”; 1 unsexed specimen ( ZMUM): “[blank label without any data] // Cryptopleurum aequinoctialis Motschulsky Paralectotype, M. Hansen des. 1993 (not conspecific with lectotype) // Oosternum costatum Sharp, M. Hansen det.”.

Additional material examined (474): BOLIVIA: 11 unsexed specimens ( KSEM, NMPC): Cochabamba Department, Cochabamba, 109 km E [sic!], Yungas, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1H99 026), 1480 m a.s.l., 17°8'50"S, 65°42'29"W, 1–6.ii.1999, R. Hanley lgt.; 1 female ( KSEM): Cochabamba Department, Cochabamba, 105 km E [sic!], Yungas, near Rio Carmen Mayu, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1H99 024), 1750 m a.s.l., 17°8'51"S, 65°43'50"W, 1–6.ii.1999, R. Hanley lgt.; 2 males, 1 female, 2 unsexed specimens ( KSEM): Cochabamba Department, 67.5 km NE of Cochabamba, Estación Biológica Valle de Sajita, Universidad de San Simon, flight intercept trap ( BOL 1H99 057), 300 m a.s.l., 17°6'33"S, 64°47'52"W, 7–9.ii.1999, R. Hanley lgt.; 1 female, 3 unsexed specimens ( KSEM, NMPC): Cochabamba Department, Cochabamba, 109 km E [sic!], Yungas, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1H99 050), 1480 m.a.s.l., 17°8'50"S, 65°42'29"W, 6–8.ii.1999, R. Hanley lgt.; 1 unsexed specimen ( KSEM): Cochabamba Department, Cochabamba, 105 km E [sic!], Yungas, near Rio Carmen Mayu, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1G99 058), 1800 m a.s.l., 17°8'47"S, 65°43'55"W, 8–12.ii.1999, F. Geniér lgt.; 1 unsexed specimen ( KSEM): Cochabamba Department, Cochabamba, 109 km E [sic!], Yungas, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1G99 027), 1480 m a.s.l., 17°8'50"S 65°42'29"W, 1–6.ii.1999, F. Geniér lgt.; 1 male, 1 unsexed spec. ( KSEM, NMPC): Cochabamba Department, Cochabamba, 109 km E [sic!], Yungas, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1G99 060), 1400 m a.s.l., 17°8'52"S, 65°42'54"W / 8–12.ii.1999, F. Geniér lgt.; 1 male ( KSEM): Cochabamba Department, Cochabamba, 117 km E [sic!], Yungas, Cochabamba – Villa Tunari road, flight intercept trap ( BOL 1H99 062), 1040 m a.s.l., 17°6'32"S, 65°41'12"W, 8–10.ii.1999, R. Hanley lgt. COLOMBIA: 1 female ( KSEM): Magdalena department, 3 km SE of Minca, 11°08΄N 74°06΄W, 1050 m a.s.l., wet forest leaf litter (#747-5), 13.viii.1985, J. Longino lgt.; 3 males, 5 unsexed specimens ( FMNH, NMPC): Choco Department, Quebrada Docordo, between Cucurrupí & Noanama, Rio San Juan, beaten ex dry foliage, 1-5.i.1969, B. Malkin lgt. COSTA RICA: 1 unsexed specimen ( KSEM): Heredia province, La Selva [biological station], 3.2 km SE Puerto Viejo [de Sarapiquí], 100 m a.s.l., flight intercept trap, 11.iii.1992, W Bell lgt.; 1 female ( KSEM): same locality and collector, 1.ii.1992; 1 female ( KSEM): same locality and collector, 1.iii.1992; 1 male ( CMN): Heredia province, 10 km W of Puerto Viejo [de Sarapiquí], 170 m a.s.l., flight intercept traps, 2.–5.iii.1991, H. & A. Howden lgt.; 2 unsexed specimens ( KSEM): Heredia Province, La Selva Biological Research Station, 3 km S of Puerto Viejo, 80 m a.s.l., 10°26'N 84°01'W, flight intercept trap (CR1C01 062), 13–26.vi.2001, S. Chatzimanolis lgt.; 1 unsexed specimen ( KSEM): same locality and collector, flight intercept trap (CR1C01 018), 5–8.vi.2001; 2 males ( KSEM, NMPC): same locality and collector, flight intercept trap (CR1C01 029), 8–11.vi.2001; 1 male, 1 female, 45 unsexed specimens ( FMNH, NMPC): Heredia province, La Selva Field Station, Puerto Viejo de Sarapiquí, Rio Puerto Viejo, Berlese 100 cc conc. compost pile near new Lab (73 CRIII 9bLS), 10°26'N 83°59'W, 5–11.iii.1973, J. Wagner & J. Kethley lgt.; 1 male, 2 unsexed specimens ( FMNH): Limón province, Reventazon, Hamburg Farm, Gymustinups montezuma, 26.i.1931, F. Nevermann lgt. ECUADOR: 2 females ( CMN): Napo province, Jatun Sacha Biological Station, 21 km E of Puerto Napo, 400 m a.s.l., virgin rain forest, flight intercept trap, 11, vii.1994, F. Genier lgt.; 4 unsexed specimens ( CNC, NMPC): Napo province, Limoncocha [= Sucumbíos province, Limoncocha], berlese #348, 18.vi.1976, S. & J. Peck lgt.; 2 females, 3 unsexed specimens ( CMN, NMPC): Pichincha province [=Santo Domingo de los Tsachillas province], 16 km E of Santo Domingo [de los Colorados], Tinalandia [Reserva Natural], 680 m a.s.l., rainforest, malaise trapflight intercept trap, 4.v.–25.vii.1985, S. & J..Peck.; 1 female ( CNC): same locality and collectors, 700 m a.s.l.

(berlese #328), broken termite nest, 5.vi.1976; 1 female ( CMN): Pichincha province [=Santo Domingo de los Tsachillas province], Santo Domingo [de los Colorados], Rio Palenque, 250 m a.s.l., rainforest, malaise trapflight intercept trap, 5.v.–25.vii.1985, S. & J. Peck; 1 male ( KSEM): Napo province, 21 km E of Puerto Napo, Jatun Sacha Biological Station, lowland rain forest, 400 m a.s.l., 9.vii.1994, F. Geniér lgt.; 2 unsexed specimens ( KSEM): same locality data, date and collector, feces traps; 1 male, 2 unsexed specimens ( KSEM, NMPC): Zamora-Chinchipe province, Río Bombuscaro, flight intercept trap ( ECUH 96 001), 4°07'00"S, 78°59'00"W, 26.vi.–4.vii.1996, P. Hibbs lgt. MEXICO: 1 male, 2 females ( CMN, NMPC): Veracruz state, 33 km N of Catemaco, Los Tuxtlas Biological station, 22.–29.vi.1984, D. H. Lindeman lgt.; 1 unsexed specimen ( CNC): Chiapas state, Palenque, 22.–23.vi.1969, D. Bright & J. M. Campbell lgt. PANAMA: 2 males, 59 unsexed specimens ( BMHN, HHFU, NHMW, NMPC, SRBC, ZMUC): Barro Colorado, ii.–iv. and vi.–x. 1986, Henk Wolda lgt.; 1 male ( KSEM): Panama pipeline Rd., km 216, flight intercept trap, 21.vi.1993, Lingafelter lgt.; 1 male, 5 unsexed specimen ( KSEM, NMPC): 6.9 km S of Gamboa, Old Plantation Rd., 9°05'N 79°40'W, 80 m a.s.l., flight intercept trap (#266) 7–22.vi.1995, J. Ashe & R. Brooks lgt.; 1 male, 2 females, 2 unsexed specimens ( KSEM, NMPC): Colón province, 14 km N junction of Escobal & Piña Rds., flight intercept trap (PAN1AB96), 2–11.vi.1996, J. Ashe & R. Brooks lgt.; 2 unsexed specimens ( KSEM): Colón province, Parque Nacional Soberania, Pipeline road, 9°07'N 79°45'W, 17–18.v.1995, J. Jolly & C. Chaboo lgt.; 1 unsexed specimen ( KSEM): Colón province, Parque Nacional Soberania, Pipeline road km 2.0, 9°07'N 79°45'W, flight intercept trap (#1), 17–18.v.1995, J. Jolly & C. Chaboo lgt.; 1 unsexed specimen ( KSEM): Colón province, Parque Nacional Soberania, Pipeline road km 6.1, flight intercept trap (#265), 9°07'N 79°45'W, 40 m a.s.l., 7–21.vi.1995, J. Ashe & B. Brooks lgt.; 13 unsexed specimens ( FMNH, NMPC): Panama province, Canal Zone, Barro Colorado Island, tapir dung 3 days old, 1.ii.1959, CHNM Panama Zoological Expedition, H. S. Dybas lgt.; 7 unsexed specimens ( FMNH, NMPC): same locality, on human faeces, 16.–20.ii.1976, A. Newton lgt.; 1 unsexed specimen ( FMNH): same locality and collector, litter under fungusy logs, 4.ii.1976; 2 unsexed specimens ( FMNH): same locality, carrion trap, 15–26.ii.1968, J. F. Lawrence lgt.; 3 unsexed specimens ( FMNH): same locality, Berlese: rotten flowers of Pseudobombax , 19.ii.–9.iii.1975, Lawrence & Erwin lgt.; 1 unsexed specimen ( FMNH): same locality, 28.i.1959, H. S. Dybas lgt.; 133 unsexed specimens ( FMNH, MACN, NMPC, SRBC): same locality and collector, Berlese: tapir dung 7 days old, 1.ii.1959; 1 male, 1 female, 9 unsexed specimens ( FMNH, NMPC): same locality and collector, debris from abandoned bivouac of Eciton burchelli , 25.i.1959; 1 male, 1 unsexed specimen ( KSEM): same locality, FIT (PAN1C00 101), 9°11'N 79°51'W, 27–31.vii.2000, S. Chatzimanolis lgt.; 1 unsexed specimen ( KSEM): same locality data and collector, FIT (PAN1C00 021), 22.vi.2000; 5 unsexed specimens ( KSEM): same locality data and collector, FIT (PAN1C00 087), 17.–23.vii.2000; 1 unsexed specimen ( KSEM): same locality data and collector, FIT (PAN1C00 054), 9.vii.2000; 1 unsexed specimen ( KSEM): same locality data and collector, FIT (PAN1C00 110), 4.viii.2000; 10 unsexed specimens ( KSEM, NMPC): same locality data and collector, FIT (PAN1C00 024), 40 m a.s.l., 22–25.vi.2000; 1 unsexed specimen ( KSEM): same locality data and collector, FIT (PAN1C00 060), 11–12.vi.2000; 1 unsexed specimen ( KSEM): same locality data, FIT, 8.vii.1994, D. Banks lgt.; 2 unsexed specimens ( KSEM): same locality data and collector, 11.viii.1994; 1 unsexed specimen ( KSEM): same locality data and collector, 1.viii.1994; 2 unsexed specimens ( KSEM): same locality data and collector, 24.viii.1994; 14 unsexed specimens ( KSEM, NMPC): same locality data and collector, 6.viii.1994; 1 unsexed specimen ( FMNH): Panama province, Canal Zone, Piña, Berlese: thin muddy litter in ravine, 25.ii.1959, CNHM Panama Zoological Expedition, H. S. Dybas lgt.; 1 female, 13 unsexed specimens ( FMNH, NMPC): Panama prov., Madden Lake [= Lago Alajuela] env., pocket of damp leaves in dry stream bed, 15.ii.1959, CNHM Panama Zoological Expedition, H. S. Dybas lgt.; 1 male, 12 unsexed specimens ( FMNH, NMPC): Panama province, Las Cumbres, Berlese (B-268) fibrous trunk in compost pile, 15.ii.1959, H. S. Dybas lgt.; 1 male ( FMNH): same locality and collector, Berlese: damp pockets of leaves & debris in stream-bed, 6.ii.1959; 1 male ( KSEM): Darién province, Cana Biological Station, 7°45'18"N, 77°41'06"W, 530 m a.s.l., flight intercept trap (PAN1AB96), 3–7.vi.1996, J. Ashe & R. Brooks lgt.; 1 male, 2 unsexed specimens ( FMNH): Bocas del Toro province, Almirante, berlese #B-639 from decaying cacao pods, 27.iii.1959, H. S. Dybas lgt.; 2 unsexed specimens ( FMNH, NMPC): Panama, Cocle province, El Valle, trail to Las Minas from “La Mera”, horse manure along trail, 2400–2600 feet [= 730–800 m a.s.l.], 21.ii.1959, H. S. Dybas lgt. PERU: 3 females, 4 unsexed specimens ( KSEM, NMPC): Madre de Dios region, Tambopata province, 15 km NE of Puerto Maldonado, Reserva Cuzco Amazónica, 12°33΄S 69°03΄W, 200 m a.s.l., ex: flower fall (#058), 14.vi.1989, S. Ashe & R. Leschen lgt.; 2 males, 1 female, 9 unsexed specimens ( KSEM, NMPC): Loreto region, 1.5 km of Teniente Lopez, 2°35.66΄S 76°06.92΄, 210–240 m a.s.l., ex: palmfruit berlese (#113), 17.vii.1993, R. Leschen lgt.; 1 male, 1 female, 5 unsexed specimens ( KSEM, NMPC): Madre de Díos region, Cocha Cashu Biological Station, Manu National Park, flight intercept trap ( PERU 1B00 042), 350 m a.s.l., 11°53'45"S 71°24'24"W, 7–19.x.2000, R. Brooks lgt.; 1 unsexed specimen ( KSEM): Madre de Dios region, Pantiacolla Lodge, Alto Madre de Dios River, flight intercept trap ( PERU 1B00 099), 400 m a.s.l., 12°39'22"S 71°13'55"W, 23–26.x.2000, R. Brooks lgt.; 1 unsexed specimen ( KSEM): Madre de Dios region, 2–7 km NW of Pantiacolla Lodge, El Mirador Trail, Alto Madre de Dios River, flight intercept trap ( PERU 1B00 101), 450–700 m a.s.l., 12°39'10"S 71°15'28"W, 23–26.x.2000, R. Brooks lgt. VENEZUELA: 1 male, 2 unsexed specimens ( CMN, NMPC): Miranda State, 35 km N of Altagracia [de Orituco], Guatopo National Park, Aqua Blanca, ravine, flight intercept traps (87-2), 31.v.–7.vi.1987, S. & J. Peck lgt.; 2 unsexed specimens ( KSEM): Miranda State, Guatopo National Park, El Lucero, 28 km N of Altagracia [de Orituco], 700 m a.s.l., forest ravine, flight intercept traps (87–19), 7.–14.vi.1976, S. & J. Peck; 1 unsexed specimen, 1 female ( CNC, FMNH): Aragua State, Cuyagua, 10 km E of Ocumare, berlese #195, cacao pod litter, 20.ii.1972, S. Peck lgt.

Lectotype designation. Lectotype and paralectotypes were designated by M. Hansen and all data on the type material are adopted from his original manuscript. Only the paralectotype housed in ZMUC was examined by M. Fikáček.

Differential diagnosis: Body widest at midlength; pronotum weakly convex; pronotal punctation dense, consisting of small, scar-like punctures; pronotal interstices with microsculpture; median carina of prosternum without anterior tooth; preepisternal elevation of mesothorax 1.9× longer than wide; median portion of metaventrite with microsculpture laterally, without microsculpture mesally; eyes large, separated by 5.0× of one eye; parameres with very large inner projections; lateral projections of median lobe wide, developed only in apical 0.35 of median lobe.

The species is easily recognizable according to dull pronotum (i.e. bearing microsculpture), elongate oval body and shiny elytra. Usually, the species is brown to dark brown colored and is very characteristic by the shape of pronotum, which is apparently “bumpy” along posterolateral margins ( Figs. 32 , 56 ). In this aspect, O. aequinoctiale is similar to O. latum , which body is however very wide and widest at junction of pronotum and elytra. Aberrant specimens are very easily recognizable according to male genitalia with very large inner projections of parameres (Fig. 46).

Redescription. HABITUS: Body elongate oval, widest ca at midlength, moderately convex in lateral view, gradually narrowing posteriad; TL/TW ratio = 1.6. Length: 1.15–1.55 mm, length of HT: 1.50 mm; width: 0.70–0.90 mm, width of HT: 0.85 mm.

COLORATION. Coloration of dorsal side brown to dark brown, anterior margin of clypeus and elytral apex slightly paler. Ventral side brown, mentum and median part of prosternum rusty brown. Femora, tibiae and antennal club reddish brown, tarsi, mouthparts and antennomeres 1–6 yellowish.

HEAD. Clypeus with dense punctation consisting of minute, sharply impressed, slightly scar-like punctures, each puncture bearing fine decumbent yellowish seta; interstices with fine microsculpture; anterior margin slightly concave. Frons with moderately dense punctation consisting of minute, sharply impressed, slightly scar-like punctures, punctures of same shape medially and laterally; interstices with fine mesh-like microsculpture. Eyes moderately large, separated by 5.0× of width of one eye. Mentum 2.3× wider than long, anterior margin deeply emarginate; punctation consisting of small, quite unsharply impressed round punctures bearing minute setae; interstices with fine mesh-like microsculpture. Submentum without poriferous disc-like ereas. Maxillary palpus with palpomeres 2 and 4 ca. 1.5× longer than palpomere 3. Scapus ca. as long as antennomeres 2–6 combined; antennal club ca. 2.3× longer than wide.

PROTHORAX. Pronotum slightly more convex than elytra; punctation consisting of small, sharply impressed round to slightly scar-like punctures, slightly sparser laterally than medially; interstices with microsculpture. Median carina of prosternum straight in lateral view. Median portion of prosternum as wide as long, postero-mesal projection with shallow notch, pits laying next to ridges delimiting prosternal plate – Habitus of the species in dorsal (a) and lateral (b) views. 36: O. aequinoctiale ; 37: O. holosericeum ;

38: O. acutheca ; 39: O. attenuatum ; 40: O. gibbicolle ; 41: O. latum .

FIGURES 42–47. Aedeagus. 42: O. acutheca ; 43: O. attenuatum ; 44: O. gibbicolle ; 45: O. latum ; 46: O. aequinoctiale ; 47: O. holosericeum .

FIGURES 48–55. Pronotal punctation and microsculpture. 48–49: O. acutheca ; 50–51: O. attenuatum ; 52–53: O. gibbicolle ; 54–55: O. latum .

MESOTHORAX. Scutellar shield bearing a few minute punctures, interstices with fine mesh-like microsculpture. Elytral series 1–6 arising basally, series 7–8 arising subbasally, series 9 nearly reaching elytral base. Elytral series 7 and 8 markedly closer to each other than to other series. Serial punctures fine and sparse. Elytral intervals moderately convex at suture; intervals 5, 7 and 9 distinctly higher than adjacent intervals; punctation irregular on all intervals, consisting of sparsely arranged minute, scar-like punctures. Elytral interstices shiny, without microsculpture. Epipleuron narrowing posteriad, reaching level of metathorax. Preepisternal plate suboval, 1.9× longer than wide; median part flat, bearing densely arranged, large, shallow setiferous punctures; interstices without microsculpture.

METATHORAX. Punctation of median portion of metaventrite sparse, consisting of small, sharply impressed rasp-like punctures; interstices without microsculpture medially, with weak microsculpture laterally. Anepisternum 6.8× longer than wide.

LEGS. Tarsi with short and sparse pubescence ventrally.

ABDOMEN. Ventrite 1 with additional longitudinal ridges laterally.

MALE GENITALIA. Paramere 1.4× longer than phallobase, with large inner projection, bearing two short setae apically. Phallobase narrow, 1.4× longer than wide. Median lobe slightly narrowing towards apex; lateral projections large, developed in apical 0.3 of median lobe.

Variation: Very variable species in size and coloration, but rather constant in all remaining characters. Some examined specimens from Bolivia are rather dark colored and bear a slight superficial microsculpture on elytra and on lateral parts of the median portion of the metaventrite. By these characters they resemble O. holosericeum , but they still differ from it by smaller body size, finer punctation of the median portion of the metaventrite (compare Figs. 76 and 77). Male genitalia and other external characters of all examined Bolivian specimens correspond well with those of O. aequinoctiale .

Habitat: Examined specimens were mostly collected in various kinds of decaying plant matter (leaf litter, palm fruits, cacao pod litter) or using flight intercept traps in montane to lowland tropical rain forest (ca. up to 1500 m a.s.l.). Occasionally, the specimens were also collected from mammal excrements (human and tapir) and in abandoned bivouac of Eciton burchelli army ant.

Distribution: Widely distributed from southern Mexico through Central America and the northern coast of South America southward along the Andes to central Bolivia.

Figures

FIGURES 32 – 35. Habitus of the representatives of O. aequinoctiale group. 32: O. aequinoctiale; 33: O. gibbicolle; 34: O. holosericeum; 35: O. latum.

FIGURES 56 – 59. Pronotal punctation and microsculpture. 56 – 57: O. aequinoctiale; 58 – 59: O. holosericeum.