Ochterus pseudomarginatus, Polhemus & Polhemus, 2012

Polhemus, Dan A. & Polhemus, John T., 2012, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Ix. Infraorder Nepomorpha, Families Ochteridae And Gelastocoridae, Raffles Bulletin of Zoology 60 (2), pp. 343-359 : 349-351

Ochterus pseudomarginatus , new species

( Figs. 3 , 13–16 , 32 )

Material examined. — Holotype, male, MALAYSIA, Johor, Endau Rompin, Sungai Pantai Burung, off Sungai Endau , 13 Jul.2001, YCM0259 , coll. C. M. Yang ( BPBM) . Paratypes: MALAYSIA, Johor: 1 male, 1 female, same data as holotype ( ZRC); 5 males, 2 females, Lombong [NW of Kota Tinggi], 16 Sep.1975, coll. D. H. Murphy ( ZRC); 1 male, Sungai Rengit, 11 mi. from Pengarang , 9 Dec.1961, coll. K. J. Kucheria ( BPBM); 1 female, Kota Tinggi Waterfall, 16 km. N. of Kota Tinggi , 200 ft., 15 Oct.1986, CL 2217, coll. D. A. & J. T . Polhemus ( JTPC) . Selangor: 1 female, Kepong , FRIM , Sungai Kroh, 15 Jan.2002, coll. H. H. Tan ( ZRC); 2 males, Gombock River , 24 km. E. of Kuala Lumpur on old Kuantan hwy., 16 Aug.1985, CL 2068, coll. D. A. & J. T . Polhemus ( JTPC); 1 male, small stream and waterfalls at Templer Park , N. of Kuala Lumpur, 110 m., 3°18'03"N, 101°37'10"E, 17 Aug.1985, CL 2070, coll. D. A. & J. T . Polhemus ( JTPC) . Pahang: 1 male, Kuala Tahan [4°23'N, 102°24"E], 4 Dec.1958, sweeping air at daytime, coll. T . C. Maa ( BPBM); 1 female, Cheroh River, 6 km. E. of Tapah , 18 Aug.1985, CL 2072, coll. D. A. & J. T . Polhemus ( JTPC) . Perak: 1 female, Kerunai River, 9 km. N. of Grik , 19 Aug.1985, CL 2078, coll. D. A. & J. T . Polhemus ( JTPC); 1 male, wet roadside rock face, 57 km. E. of Grik , 20 Aug.1985, CL 2080, coll. D. A. & J. T . Polhemus ( JTPC) . Kelantan: 1 male, Pergau River at upper bridge, 24 km. W. of Jeli , 560 m., 5°37'37"N, 101°42'31"E, 20 Aug.1985, CL 2082, coll. D. A. & J. T . Polhemus ( JTPC) . SINGAPORE: 1 male, Bukit Timah forest, JFV stream side, 18 Jul.1979, coll. D. H. Murphy ( ZRC); 1 male, Bukit Timah forest, Tabon Valley , 1 Apr.1976, coll. D. H. Murphy ( ZRC); 1 female, Bukit Timah Nature Reserve , Jungle Falls Valley , 100 m., 12 Oct.1986, CL 2212, coll. D. A. & J. T . Polhemus ( JTPC) . INDONESIA, Bengkulu Prov.: 2 males, 2 females, Airgedang River , 23 km. E. of Bengkulu on Curup rd. , 90 m, 3°45'29"S, 102°24'42"E water temp. 31.5°C., 6 Sep.1991, CL 2581, D. A. & J. T . Polhemus ( JTPC, BPBM) .

pronotum dark yellow; scattered pruinose lavender markings as follows: small, transverse patches along posterolateral sections of pronotum immediately behind eyes, 6 small irregular patches arranged transversely across central portion of pronotum; small, longitudinally elongate, semi-triangular patch medially at anterior margin of scutellum; 3 prominent, roughly circular patches equally spaced along central portion of outer forewing margin on each hemelytron with 2 on posterior half of embolium and one on posterior corium, 7–8 small, irregular patches arranged symmetrically on clavus and corium; punctations of head, scutellum and hemelytra marked with grey pruinosity, entire wing membrane also irregularly flecked with such pruinosity. Head shining black; eyes silvery; clypeus, labrum, and rostrum shining, dark blackish-brown, anterior margin of clypeus narrowly dark yellow, terminal segment of rostrum chestnut brown; antennae with segments I and II dull brownish yellow, segments III and IV dark brown; venter dull pruinose black; legs with femora pale yellowish white, hind tibiae pale yellowish brown, bearing very small dark brown spots at bases of spines, apices of femora, tibiae and terminal tarsal segments infuscated.

Head glabrous, length (along midline as measured from directly above)/width (across eyes) = 0.50/1.50, angled downward at greater than 45° when viewed laterally; frons and clypeus with coarse striations, inner margins of eyes bordered by narrow channels, these channels lacking transverse striations except at extreme anterior ends ( Fig. 32 ); eyes large, protruding, projecting posterolaterally beyond vertex; antennae with segments I and II short, globose, segments III and IV slender, filiform, lengths of segments I–IV = 0.10, 0.20, 0.33, 0.40; rostrum long, length = 2.80, exceeding hind coxae and extending onto base of abdominal venter.

Pronotum length (midline)/width = 1.05/2.60, bearing numerous small pruinose punctations; anterior collar prominent, flat; anterolateral margins explanate, well demarcated from disk; calli barely tumescent; posterior margin multisinuate, posteriorly concave centrally above base of scutellum. Scutellum triangular, length/width = 1.02/1.50, weakly tumescent, bearing numerous small punctations centrally plus a row of slightly coarser, more closely spaced punctations along lateral margins. Hemelytra long, attaining tip of abdomen, with corium, clavus and embolium well defined, surfaces set with scattered pruinose punctations; anterolateral embolar margin narrowly explanate; length of clavus along outside margin 1.80; membrane venation evident, defining 6 closed cells.

Ventral surface of thorax smooth and pruinose, lacking patches of long, upright, golden setae; scattered tiny, dark punctations present on pro- and mesoepisterna, a single diagonal line of punctations present on each metepisternum; abdominal venter covered with very short, fine, appressed silvery setae, this setal covering interrupted by ovate glabrous patches surrounding spiracles laterally on paratergites.

Legs with all segments covered by short, fine, recumbent pale setae; all coxae bearing long, pale setae ventrally; fore and middle trochanters and basal halves of fore and middle femora with very long, erect, slender, pale setae ventrally, remainder of ventral margins bearing moderate length, upright, slender, pale setae; hind femur broadly and gently bowed downward when viewed laterally; all tibiae bearing numerous short, bristly golden setae, these setae becoming more numerous distally; hind tibia with 8 long, stout, semi-erect, spine-like golden setae on posterior margin, 5 of these setae occurring on distal third of tibia; claws golden, gently curving, arolia long, exceeding length of claws when viewed laterally. Lengths of leg segments as follows: fore femur/tibia/tarsal 1/tarsal 2 = 1.25/1.15/0.05/0.20; middle femur/tibia/tarsal 1/tarsal 2 = 1.50/1.30/0.03/0.27; hind femur/tibia/tarsal 1/tarsal 2/tarsal 3 = 1.60/2.30/0.01/0.30/0.18.

Genital segment well retracted into abdomen; subgenital plate with V-shaped indentation medially on posterior margin. Pygophore with caudal tip blunt, broadly rounded, lateral lobes well removed from apex ( Fig. 15 ). Right paramere with head of moderate height, domed and convex; appendices of similar size, moderately long, apices multiserrate, one of these processes with apex bearing numerous small serrations, the other with the apex bearing a large tooth plus additional smaller serrations ( Fig. 14 ); paramere shaft stout basally, evenly tapering distally ( Fig. 13 ); phallotheca with distal process bearing lateral flanges, shape as in Fig. 16 .

Female. Similar to male in general structure and colouration, body length 4.80–5.20, maximum width (across hemelytra) 2.70–2.90. Head length (along midline as measured from directly above)/width (across eyes) = 0.30/1.50; lengths of antennal segments I–IV = 0.08, 0.20, 0.40, 0.30; rostrum length = 2.90, exceeding hind coxae and extending onto base of abdominal venter. Pronotum length (midline)/width = 1.25/2.55. Scutellum length/width = 0.90/1.50. Hemelytra with length of clavus along outside margin 1.95. Lengths of leg segments as follows: fore femur/tibia/tarsal 1/tarsal 2 = 1.30/1.20/0.11/0.11; middle femur/tibia/tarsal 1/tarsal 2 = 1.40/1.20/0.14/0.07; hind femur/tibia/tarsal 1/tarsal 2/tarsal 3 = 1.65/2.20/0.07/0.35/0.20.

Etymology. — The name “ pseudomarginatus ” refers to the superficial similarity in appearance of this species to Ochterus marginatus , with which it has been previously confused in various collections.

Distribution. — Peninsular Malaysia, Singapore, and Sumatra

Discussion. — Ochterus pseudomarginatus is, as its name implies, superficially similar in general appearance to O. marginatus , a species widespread in the Paleotropical Region. Externally, the two species may be separated by their colour patterns, with the prominent pale spots along the hemelytral margin being dark yellow in O. marginatus ( Fig. 1 ) and pruinose lavendar in O. pseudomarginatus ( Fig. 3 ). In particular, if O. marginatus specimens are examined while in alcohol one can see the depigmented sections of the lateral hemelytron where the pale marginal patches lie, while by contrast specimens of O. pseudomarginatus examined under similar conditions show no such depigmented patches, with the lateral markings on the hemelytra being the result of surface pruinosity rather than depigmentation. In addition, the violet pruinose markings on the dorsum of O. pseudomarginatus consist of distinct, relatively solid patches and spots, whereas on O. marginatus such markings are more diffusely scattered as many small dots and diffuse patches (compare Figs. 1, 3 ).

Internally, males of O. pseudomarginatus may be easily separated from those of O. marginatus by the structure of the right paramere (compare Figs. 5–7 and 13, 14 ), in particular the superior appendage, which is multidentate and lacks asperities in the former species (Fig, 14), while being unidentate and bearing small asperities in the latter ( Figs. 6, 7 ).

joints black on dorsal surfaces; antennae with all segments pale whitish-yellow; venter of head and thorax dull pruinose black, abdominal venter brown; legs pale yellowish white, extreme apices of femora, tibiae and terminal tarsal segments infuscated. Head length (along midline as measured from directly above)/width (across eyes) = 0.30/1.33, angled downward at nearly 90° when viewed laterally; frons with coarse striations, these striations becoming somewhat finer and more numerous on clypeus, inner margins of eyes bordered by narrow channels, these channels lacking transverse striations ( Fig. 34 ); eyes large, protruding, projecting posterolaterally beyond vertex; antennae with segments I and II short, globose, segments III and IV slender, filiform, lengths of segments I–IV = 0.10, 0.10, 0.20, 0.35;

Ecological notes. — Ochterus pseudomarginatus occurs along rocky streams in hill forest areas, in contrast to O. marginatus which occurs on sand bars and mud flats in the lowlands.

Figures

Figs. 1–4. Ochterus species, colour photographs of dorsum. 1, O. marginatus (Latreille), specimen from Thailand, Chonburi Prov. 2, O. signatus, new species, specimen from Malaysia, Perak, CL 2081. 3, O. pseudomarginatus, new species, specimen from Malaysia, Pahang, CL 2072. 4, O. singaporensis, new species, specimen from Singapore, Bukit Timah.

Figs. 13–16. O. pseudomarginatus, new species, male, structural details, specimen from Malaysia, Perak, CL 2078. 13, Male right paramere. 14, Superior appendage of right paramere. 15, Medial process of pygophore. 16, Endosoma.

Figs. 29–34. Ochterus species, colour photographs of head, anterior view, showing pattern of striations on frons.29, O. marginatus (Latreille), female, specimen from Vietnam, Cao Bang Prov., CL 4368. 30, O. thienemanni Jaczewski, female, specimen from Indonesia, Bali Prov., CL 2170. 31, O. signatus, new species, female, specimen from Vietnam, Lam Dong Prov., CL3085. 32, O. pseudomarginatus, new species, female, specimen from Malaysia, Perak, CL 2078. 33, O. noualhieri Baehr, female, specimen from Indonesia, Sulawesi Utara Prov., CL 2114. 34, O. singaporensis, new species, male, specimen from Singapore, Bukit Timah.

Figs. 5–9. O. marginatus (Latreille), male, structural details. 5, Male right paramere, specimen from Vietnam, CL 4368.6, Superior appendage of right paramere, specimen from Vietnam, CL 4368. 7, Superior appendage of right paramere, specimen from Indonesia, Bali, CL 2170. 8, Medial process of pygophore, specimen from Vietnam, CL 4368. 9, Medial process of pygophore, specimen from Indonesia, Bali, CL 2170.