Bembecinus proximus (Handlirsch 1892)

Bembecinus proximus (Handlirsch)

Stizus reversus Smith.—Cameron, 1890:246–247, pl. 10: fig. 1 [misidentification].

Stizus proximus Handlirsch, 1892:45–46 [, ; “species orientalis”]; 1895:977, 1035 [listed].—Bingham, 1897:283 [brief description].—Dalla Torre, 1897:529 [listed].—Turner, 1917:182 [records specimens from Anamalai Hills, South India, and Cocos Islands].

Bembecinus proximus (Handlirsch.)—Vecht, 1949:306 [brief notes].—Bohart and Menke, 1976:532 [listed].

Handlirsch noted in his original description that the species was based on a pair from the Oriental Region identified as Stizus reversus Smith by Cameron. Later, Handlirsch (1895:977) recorded a female from Burma, and noted that S. proximus would become a synonym of S. reversus if Smith's species was actually identical. He noted in his systematic-geographic table (1895:1035) that the type series of S. proximus came from India. Bingham did not see S. proximus and provided only a brief color description taken from Handlirsch (1892). Vecht (1949) in his notes on Indo-Australian species suggested that the male should be selected as lectotype. Cameron (1890:247) had noted variation in the quantity of yellow on the abdomen and legs, so undoubtedly he confused several species under what he misidentified as the Indonesian Stizus reversus.

The syntype series consists of a single pair in the Vienna Museum, each bearing only one label, “proximus/det. Handl.” Inasmuch as the specimens were sent to Handlirsch by Cameron, it is probable that they were captured by Rothney at Barrackpore near Calcutta. Both agree very well in morphological characters with the extensive series of B. proximus that I have assembled from many localities in Sri Lanka and from several localities in South India. The syntypes have the pale markings more of a creamy color than the more intense yellow of Ceylonese specimens, and the paired spots on the first tergum are somewhat larger. Specimens from South India also have creamy markings. I have selected the male syntype as the lectotype.

As noted in the discussion of the previous species, B. pusillus (Handlirsch), these two taxa are distinct from all other Ceylonese Bembecinus except B. knighti in lacking a notch or emargination on the posterolateral angle of the propodeum (cf. Figures 1, 6). Bembecinus proximus and B. pusillus are distinguished readily from each other, as noted in the discussion of the latter species.

Bembecinus proximus and B. pusillus are the most widely distributed species of the genus within Sri Lanka, and the former is more abundant than the latter. The present species occurs in both the Dry Zone and the Wet Zone from sea level to 700 m, and in areas with average annual rainfall ranging from 965 to 3900 mm. I have seen the species also from South India and Bengal.

FEMALE.—Length 6.7–9.4 mm. Black, the following yellow: palpi, labrum, clypeus except occasionally extreme base, supraclypeal area varying from entirely yellow to entirely black, narrow stripe along inner eye margin extending upward halfway between antennae and anterior ocellus and sometimes downward to base of clypeus, band on apical margin of pronotum and lobe, lateral stripe or posterolateral spots on scutum, spot on lateral fourth of scutellum, band on median half or third of postscutellum, stripe of variable length on posterolateral angle of propodeum, apex of fore coxa, stripe beneath on fore and midfemora, stripe on outer surface of fore and midtibiae, spot at base of hind tibia, fore and midtarsi except posterior edge of basitarsi, wide subapical spots on tergum I sometimes very narrowly separated on midline, apical band on tergum II broadly and shallowly biemarginate on anterior margin, narrow apical band on tergum IV on median half or two-thirds, small oval posterolateral spot on tergum V, and triangular posterolateral spots on sterna II-IV diminishing in size on successive sterna, those on II sometimes connected by a narrow apical band. Wings clear, veins brown.

Ocular index 1.8–1.9; distance between antennal scrobe and inner eye margin 1.3 times distance between scrobe and base of clypeus; ocellar area without median groove behind anterior ocellus.

Second submarginal cell strongly narrowed above but not petiolate.

Median triangular area of propodeum narrowly impunctate anteriorly except at sides, mostly subcontiguously punctate elsewhere; posterolateral propodeal margin rounded, not notched (Figure 6).

Tergum VI with narrow median impunctate strip; sterna II and III with larger more scattered punctures than in B. comberi (cf Figures 27, 28).

MALE.—Length 6.7–8.3 mm. Color as in female except as follows: supraclypeal area entirely pale except rarely very narrowly at side, stripe along inner eye orbit extending to base of clypeus, posterolateral spot on scutum rarely lacking, band on postscutellum sometimes reduced to a small median spot, hind tarsus usually pale except apical segment; tergum V sometimes with a median spot and occasionally lateral spots joined by an apical band, and sternum V with a triangular posterolateral spot, which is occasionally tiny.

Ocular index 2.3–2.4; distance between antennal scrobe and base of clypeus 2.0–2.5 times distance between scrobe and inner eye margin.

Second submarginal cell and propodeum as in female.

Apical margin of sternum VI broadly and shallowly emarginate; sternum VII with median ridge on basal half; ventral aspect of genitalia (Figure 20), outer margin of paramere narrowed at middle, its apex more broadly rounded than in B. pusillus, cuspis shorter than in B. knighti.

SPECIMENS EXAMINED (all USNM except where noted).—NORTHERN PROVINCE. District Unknown: 1, Pudavaikaddu, 2 Jul, Keiser (Basel). Jaffna District: 3, 1, Kilinochchi, 24–27 Jan, 80 ft (24 m), Krombein et al. Mannar District: 5, 2, 0.5 mi (0.8 km) NE Kokmotte Bungalow, Wilpattu National Park, 50–100 ft (15–30 m), 22 and 23 Jan (3, 2), 15 and 16 Feb (1), 22–25 May (1 in Malaise trap), Krombein et al.

NORTH CENTRAL PROVINCE. Anuradhapura District: 1, Kalkudiya Pokuna, Mihintale, 11 Mar, P.B. Karunaratne (31176 C); 1, Padaviya Archeological site, 60 m, 11–14 Oct, Krombein et al.; 1, Ritigala Natural Reserve, 24 and 25 Feb, Krombein et al.

EASTERN PROVINCE. Trincomalee District: 14, 26, China Bay Ridge Bungalow, 0–100 ft (0–30 m), 27–31 Jan (2, 7), 25–50 ft (8–15 m), 26 Feb (3, 1), 0–100 ft (0–30 m), 13–17 May (6; 1 in Malaise trap), 0–30 m (0–9 m), 8–11 Oct (3, 18; 3 in Malaise trap), Krombein et al. Amparai District: 8, 7, Ekgal Aru Sanctuary Jungle, 100 m, 19–22 Feb (1, 5), 9–11 Mar (7, 2), Krombein et al.

CENTRAL PROVINCE. Matale District: 1, Sigiriya, 18 Jun, Krombein et al. Kandy District: 1, Ambacotta, 13 Dec, Keiser (Basel); 2, Hasalaka, 17 Feb, P.B. Karunaratne (21777 C and D); 5, Thawalamtenne, 21 Mar (1 in Malaise trap), 740–760 m, 16–18 Sep (4), Krombein et al.; 15, 1, Kandy (includes Udawattakele Sanctuary, Lady Blake's Drive, Lady Horton's Drive, Roseneath, Pitakanda), 8–11 Feb (1); 25 Mar (6 in Malaise trap); 19 June (1); 5–15 (1), 13 (1), and 20–30 Jul (1); 16–31 (1) and 20 Aug (1); 30 Sep (1); 1–3 Oct (1); 16 Dec (1), S. Karunaratne, Keiser, Krombein et al., Spangler et al. (USNM, Basel); 1, Peradeniya Central Agricultural Center, 25 May, Halstead (San Francisco).

NORTH WESTERN PROVINCE. Kurunegala District: 1, Badegamuwa Jungle, 24–27, Krombein et al.

WESTERN PROVINCE. Colombo District: 2, Papiliyana, Nugegoda, 17 May and 24 Nov, P.B. Karunaratne; 1, Kohugala, Nugegoda, 6 Jun, Krombein et al.; 3, Labugama Reservoir Jungle, 2–4 Feb (1), 110 m, 29 Oct (2), Krombein et al.

SABARAGAMUWA PROVINCE. Kegalla District: 1, Kitulgala, Makande Mukalana, 3 and 4 Feb, Krombein et al. Ratnapura District: 1, Uggalkaltota, 23–26 Jun, Krombein et al.; 11, 8, Gilimale, Induruwa Jungle, 2 (1, 2) and 5–7 Feb (4), 7 and 8 (6, 4; 3 in Malaise trap) and 13–15 Mar (2), Krombein et al.; 8, 16, Sinharaja Jungle, 2 mi (3.2 km) S of Weddagala, 8–12 Feb (5, 16; 1 is 21277 B, 1 at black light, 1 at extrafloral nectary of Macaranga digyna), 16–21 Jun (3), Krombein et al.

UVA PROVINCE. Monaragala District: 1, Mau Aru, 10 mi (16 km) E of Uda Walawe, 100 m, 24–26 Sep, Krombein et al.; 9, Angunakolapelessa, 100 m, 21–23 Jan (2 are 12279 B and C, 1 in Malaise trap), 27 and 28 Mar (1 in Malaise trap), Krombein et al.; 1, Okkampitiya, 1–10 Dec, P.B. Karunaratne (Ottawa).

SOUTHERN PROVINCE. Galle District: 1, Kottawa Forest, 23 Oct, Robinson et al.; 19, 4, Sinharaja Jungle, Kanneliya section, 11–16 Jan (12, 2; 7 in Malaise trap), 11 and 12 Mar, 500 ft (152 m) (1, 2), 13–16 Aug (2), 2–5 (1) and 6–12 Oct, 400 ft (122 m) (3), Krombein et al. Hambantota District: 1, Yala, 22 Oct, Keiser (Basel); 2, Palatupana tank, 15–50 ft (4–15 m), in Malaise trap, 18–20 Jan and 3 and 4 Feb, Krombein et al.

Bembecinus proximus (Handlirsch)

We made biological observations on six females of this species, 31176 C at Mihintale, 21277 B at Weddagala, 21777 C and D at Hasalaka, and 12279 B and C at Angunakolapelessa.

The two nests at Hasalaka yielded the most information. They were constructed in a newly cleaned, flat, dirt road with scattered gravel on the surface and finer grains beneath. Both burrows went downward at an angle of 30° to the horizontal for 7.5 cm and terminated in an almost horizontal cell 3.8 cm below the surface. The cells were 1 cm long and less than 1 cm wide. Wasp 21777 C, 7 mm long, flew in carrying a gray prey beneath her, venter to venter, and with the abdomen of the prey extending beyond that of the wasp. While holding her prey, the wasp opened the temporary closure at the burrow entrance and carried it in. She came out head first in 30 seconds, turned around, and went in again. She backed out in a few seconds and then kicked sand in backward to close the entrance, at which time she was captured. The temporary closure was very thin and there was also a thin, loose closure of sand at the entrance to the cell. The cicadellid prey were standing on their heads surrounding the egg, which was on a pedestal about 1 mm high and wide. The egg was slightly curved and 2.6 × 0.6 mm. The prey were identified as follows:

2 Selenocephalus species A, 6.5 and 7.0 mm long

1 Batracomorphus species A, 4.7 mm

2 , 1 Batracomorphus species B, 4.3 and 4.7 mm

The nest of wasp 21777 D, a specimen 8 mm long, was about 15 cm from that of wasp C. She flew in with a very large prey, opened the entrance, and carried in the prey. She came out in a short time and closed the entrance, at which time we captured her. We found a wasp larva 3–4 mm long in the cell and a number of prey which were identified as follows:

6 , 2 Selenocephalus species B, 6.1–7.5 mm long (Cicadellidae)

2 Orthophagus species, 10.2 and 10.5 mm (Dictyopharidae)

At Angunakolapelessa I caught wasp 12279 B, 7.5 mm long, at 1100, as she alighted at her open burrow entrance without prey. The nest was on a sand bank with a slope of 45° and the burrow entrance was 4 mm wide. We lost the burrow and cell but recovered a nymph 4.5 mm long of a species of Cicadellidae and an adult cicadellid, Acostemma prasina Walker, 9 mm long. At 1110 we captured wasp 12279 C, 7 mm long, as she alighted on the same bank. She was carrying her paralyzed tropiduchid prey, which has just been described as Paruzelia salome Fennah.

On 12 February we captured wasp 21277 B, 8.5 mm long, nesting in a flat, sandy loam road. Her burrow went in at an angle of 30° to the horizontal for 3.8 cm, then turned at an angle for 1.3 cm. The horizontal cell was 3.8 cm from this angle and contained a large wasp larva, a number of prey 5–6 mm long, and some dipterous maggots. The prey were identified as follows:

1 Selenocephalus species (Cicadellidae)

2 Batracomorphus species (Cicadellidae)

2 nymphs, Hylicinae species (Cicadellidae)

1 Stacota breviceps Walker (Tropiduchidae)

Six acalyptrate dipterous maggots were 3.2–3.5 mm long, and one was 1.3 mm long; the family to which they belong could not be identified.

P.B. Karunaratne found wasp 31176 C, 7 mm long, nesting in a pile of sand at Mihintale. He excavated the nest but found neither cell, egg, nor prey.

Natural Enemies

Evans (1966:143) commented that no dipterous parasites had been recorded for any species of Bembecinus, that the mutillid wasp Smicromyrme viduata (Pallas) and the chrysidid wasps Hedychrum chalybaeum Dahlbom and Holopyga chrysonota (Förster) parasitized the European B. tridens (Fabricius), and that Nysson dimidiatus Latreille was a cleptoparasite of this same species of Bembecinus.

I collected a female miltogrammine (Diptera, Sarcophagidae), Protomiltogramma seniorwhitei (Verves), following a prey-laden B. comberi (Turner) and another P. seniorwhitei as it perched on a grass stem near another nest of B. comberi. It is quite probable that if maggots of this dipteron gained access to a cell they would act as commensals rather than as parasites, for the mother wasp would supply enough food for her own larva and the maggots also due to her progressive provisioning behavior.

I found seven acalyptrate dipterous maggots, 1.3–3.5 mm long, in a cell of B. proximus (Handlirsch), together with a large wasp larva and six prey specimens. The maggots could not be identified, but it seemed likely that they were commensals inasmuch as the wasp larva was healthy and there was an abundance of prey. We also found a tiny dipterous maggot on a half-grown larva of B. pusillus (Handlirsch) and 14 prey in the cell; this dipteron also may have been a commensal rather than a parasite.

There is strong circumstantial evidence that the small Nysson horni Strand (probably a synonym or subspecies of N. rugosus Cameron) is cleoptoparasitic on most of the Ceylonese Bembecinus. This Nysson is extremely abundant everywhere that the species of Bembecinus occur except B. luteolus, new species. Although I have never seen N. horni investigating Bembecinus nests, there are no other Nyssonidae common enough to serve as hosts for so abundant a cleptoparasite. I have examined carefully all Bembecinus prey and found no Nysson egg secreted beneath the wings as is the habit in the latter genus.