Carinostigmus congruus (Walker 1860)

Carinostigmus (Carinostigmus) congruus (Walker)

Stigmus congruus Walker, 1860:304, 305 [; Ceylon; syntypes in British Museum (Natural History)].—Walker in Tennent, 1861:454 [listed].—Kohl, 1890:63 [synonymized S. niger Motschulsky].—Dalla Torre, 1897:361 [listed S. niger as a synonym].—Bingham, 1897: 266, figure 74 [; Sikhim, Tenasserim, Ceylon].—Turner, 1917:174 [listed S. niger as a synonym].

Stigmus congruens [sic] Walker.—Motschulsky, 1863:23 [listed].—Bingham, 1896:447 [listed].

Stigmus niger Motschulsky, 1863:23 [sex not stated, but ; “des Montagnes de Nura-Ellia, Ceylan”; type in Zoological Museum, Moscow State University.]

Stigmus (Carinostigmus) congruus Walker.—Tsuneki, 1954:7–8 [; Tenasserim, Sikhim, India; republished Walker's and Bingham's descriptions of S. congruus].

Carinostigmus congruus (Walker).—Bohart and Menke, 1976:191 [Sri Lanka and South India; listed S. niger as a synonym].

Stigmus congruus Walker was one of the first sphecoid wasps to be described from Sri Lanka. I have studied the syntype series consisting of three females and one male. Each bears a small, round, pale blue tag, blank on the upper side, and with “63/52” written on the lower side. C.R. Vardy advised me (in litt.) that 63/52 stands for accession 52 of 1863 (175 Coleoptera and 116 Hymenoptera from Ceylon) and includes type specimens described by Walker from 1858 through 1860. One female also is labeled “congruus” in script, perhaps in Walker's hand. It also has a small round tag with a green border bearing a printed “Type,” and a fourth label, “B.M. TYPE/HYM./21.879.” The four specimens are conspecific and agree with a species that is by far the most abundant at low altitudes in Sri Lanka. I have selected the specimen bearing the “congruus” label as the lectotype and have so labeled it.

Stigmus niger Motschulsky was described from the mountains of the Nuwara Eliya area. The material was collected by Nietner, a coffee planter and amateur coleopterist, whose home was at an altitude of 3880 ft (1183 m) (Nietner, 1859). The specimen labeled type is in deplorable condition, having been mostly destroyed, presumably by a dermestid beetle. Mounted on a card point are part of an antenna, several legs lacking some segments, and some small fragments of the thoracic sternum. Motschulsky did not mention the sex, but it is a female for the antenna does not bear the fringe of long curled setae beneath that are characteristic of the male. The trochanters are testaceous, rather than the coxae, as stated by Motschulsky; the fore tibia and tarsus are also testaceous. He gave the length as 2 lines (4.2 mm), smaller than any Ceylonese females that I have seen (the normal range is 4.5–6.0 mm long). The fore tibia of several female C. congruus is 0.6 mm long and the body length is 4.8–5.1 mm, giving a ratio of 8.0–8.5. Applying this ratio to the fore tibia of the type, which is 0.5 mm long, one obtains a body length of 4.0–4.3 mm as compared to Motschulsky's measurement of 4.2 mm.

Associated with the type, and sent as “an additional specimen,” is a headless female of C. congruus that has been attacked by mold. It bears a small label reading, “Ceyl,” but no identification label. Motschulsky did not mention how many specimens were in his type series. This second female is 4.4 mm long without the head. That would make the entire length 5.0–5.1 mm. The coloration of the legs is like that of the type. I suspect that both specimens may have been collected around Nietner's home, and that the second female lacked a head when it reached Motschulsky. I exclude it as a possible syntype because of its size. Thus I believe that the two specimens are conspecific, and agree with Kohl's (1890) synonymizing of S. niger under S. congruus. Motschulsky (1863) mentioned the range in length when he had a series that showed this variation. For example, he stated that Dolus opacicollis Motschulsky was 1–1¾ lines (3.0–3.7 mm).

If it is maintained that the headless female is a syntype, it should be selected as the lectotype. The species will then be more certainly a synonym of C. congruus. There are only three species of Carinostigmus at higher altitudes in Sri Lanka, C. clypeolus, new species, C. bucheilus, new species, and C. congruus. The former can be eliminated at once; the trochanters are dark and the petiole is shorter and stouter than that of the headless female of C. niger (cf. Figures 48, 50). The female of C. bucheilus has the anterior part of the scutum with transverse to curved rugulae (Figure 42) that are lacking in the headless specimen of C. niger (cf. Figures 38, 39). This headless specimen agrees, moreover, with females of C. congruus that have the propodeum more coarsely sculptured adjacent to the enclosure and short longitudinal ridges posteriorly on the scutum (Figure 39).

The intriguing possibility exists that the type series of both S. congruus and S. niger were collected by Nietner. Walker (1860) did not mention the collector of the 175 specimens of Coleoptera and 116 of Hymenoptera that he described from Sri Lanka. In his catalog of Ceylonese insects Motschulsky (1863) described many small Coleoptera, Hymenoptera, and representatives of other orders, as having been collected by Nietner. Nietner (1859:24) stated that he sent Ceylonese insects to various entomologists in Europe; he specifically mentioned a group of small insects he sent to Motschulsky. Although Nietner did not include Walker's name among the recipients of these collections, it seems almost incredible that there could have been two collectors of small Hymenoptera and Coleoptera in Sri Lanka during the late 1850s.

It is clear from Bingham's descriptive remarks (1897) that he had two species of Carinostigmus. Presumably he used Walker's type in his interpretation of C. congruus, although he recorded material from Sikhim and Tenasserim also. He based his description of C. niger on a specimen from Pundaluoya collected by Green. Pundaluoya is in the hill country near Nuwara Eliya (the type-locality of C. niger), but at a higher altitude of about 1285 m with surrounding hills to 1465 m. I have six females that agree very well, especially in the conformation of the clypeus (Figure 12), with Bingham's description of C. niger. They come from four localities ranging in altitude from 365 to 1770 m, and they are described below as C. clypeolus.

Convinced by the characters used by Bingham to separate C. congruus and C. niger, Kohl later recognized them as discrete species although he never published this conclusion. There are two males of C. congruus in the British Museum (Natural History) that were transferred from the Federated Malay States Museum in 1955. They are glued on a single card and were collected at Peradeniya, Ceylon, 30 Dec 1901 by Uzel. One label on the pin is “St. niger/Motsch./det. Kohl;” the “St. niger Motsch.” is in Kohl's handwriting and the “det. Kohl” is printed.

Carinostigmus congruus exhibits considerable infraspecific variation in the development of body sculpture. For example, the scutum posteriorly may be smooth or may have short longitudinal ridges (Figures 38, 39); the propodeum may be mostly smooth adjacent to the enclosure or rugulose to rugulosoreticulate (Figures 38, 39); and the abdominal petiole may be smooth or may have one or two weak lateral carinae (Figures 49, 50). These and other variations, such as in coloration, are noted in the descriptions that follow.

The species is extremely close to, if not identical with, C. iwatai (Tsuneki) from Hong Kong, China, and Taiwan, and C. thailandinus (Tsuneki) from Thailand. Additional associated males of those populations must be obtained before a decision may be made as to possible synonymy.

Carinostigmus congruus is more similar to C. griphus than to any of the other Ceylonese species. The male of C. congruus usually has the median clypeal lobe glossy rather than strongly shagreened as in C. griphus, in having the head less strongly narrowed behind the eyes (cf. Figures 16, 17) (occipital width 0.5 rather than 0.4 times head width), in having a narrower, less strongly crenulate occipital groove, and in having weaker lateral rugae on the venter of the head (cf. Figures 24, 25). The female is separated from that of C. griphus with considerable difficulty. The median lobe of the clypeus (cf. Figures 9, 10) is more convex, glossy rather than usually delicately shagreened at the base, and has a narrower apical margin. The declivous surface of the pronotum anterior to the transverse ridge is smooth or has evanescent irregular rugulae rather than vertical rugae, and the ratio of the interocular distance at the anterior ocellus to that at antennal insertions is slightly greater.

The female of C. congruus is distinguished at once from those of C. clypeolus and C. bucheilus by having a stronger frontal ridge with a projection near the middle (cf. Figures 18, 19). The female also has a narrower labrum and clypeal lobe than in those species. Both sexes of C. congruus differ from those of C. costatus, new species, in having the venter of the head with a larger median delicately punctured area with only a few rugae laterally (Figures 20, 24), rather than having a smaller lineolate or rugulose area medially and many strong parallel costae adjacent to the punctate area (Figure 21). The trochanters are always testaceous in C. congruus, as well as additional parts of the legs, whereas the trochanters in C. costatus are dark and the rest of the legs have fewer parts testaceous. The pronotal crest is weaker than in C. costatus and does not have a median emargination. Finally, the male has short filiform maxillary palpi rather than elongate, flattened and broadened palpi fringed on the inner side by long curled setae as in C. costatus.

The present species is widely distributed in both the Wet Zone and the Dry Zone, but it has not been collected in a number of the most xeric areas of the Dry Zone, and is most common in areas with an average annual rainfall of 1100–3900 mm. We collected only one specimen at Palatupana Tank, an area we visited on nine trips, where the average annual rainfall is only 860 mm. Carinostigmus congruus occurs from near sea level to an altitude of at least 1830 m. It is found also in India and Nepal and may range more widely.

This is an extremely abundant species at lower altitudes in all but the more marginal xeric habitats. We collected nearly 450 specimens of Carinostigmus during the active years in the field of the Smithsonian Ceylon Insect Project (1970–1981), and only 37 of them belonged to the other four species known to occur in Sri Lanka. Dates of capture at such localities as Kandy, Labugama, Weddagala and Gilimale, suggest that C. congruus breeds throughout the year under favorable conditions.

FEMALE.—Length 4.5–6.0 mm. Black, glossy, vertical aspect of face dull from delicate shagreening, pronotal lobe white to ivory, mandible except base and apex, and labrum light red, the following testaceous: palpi, scape usually entirely but sometimes infuscated above, part or most of underside of flagellum, tegula, trochanters, at least underside of fore and mid tibiae, and also tarsi usually; fore and mid tibiae rarely dark brown, and apices of tarsi, fore femur beneath rarely, and hind tarsi rarely infuscated. Wings clear, stigma black, veins dark brown.

Head in frontal view (Figure 3); eyes diverging above, interocular distance at anterior ocellus 1.4 times that at antennal insertions; viewed from above head moderately narrowed behind eyes, width at occiput half the greatest width (Figure 15); clypeus (Figure 9) more convex in middle than in C. griphus, median lobe narrower, strongly produced, apex slightly emarginate, margin laterad of lobe gently incurved; labrum narrow, pentagonal, sides straight near apex; frontal ridge strong (Figure 18), present only on vertical surface of front, near middle with a T-shaped projection; ocular groove crenulate and moderately broad along vertical section of inner eye margin; vertical surface of face delicately shagreened, occasionally more roughened or with very short oblique rugulae adjacent to ocular groove; horizontal surface of front and vertex with sparse, tiny punctures, shallow groove before anterior ocellus evanescent or absent; occipital groove narrow, smooth, not crenulate; underside of head with a few weak rugae laterally which are occasionally evanescent, a large median area with small, moderately close punctures.

Thorax in dorsal (Figures 38, 39) and lateral (Figures 44, 45) views; anterior pronotal ridge weaker than in C. costatus, not emarginate in middle, lateral angles not so strong, declivous slope before ridge smooth or with irregular evanescent rugulae; notauli strongly impressed, crenulate, parapsidal lines weakly impressed; scutum with punctures stronger and denser than on head, posteriorly with short, well-developed ridges varying to almost without ridges; scutellum anteriorly with narrow crenulate groove, discally with a few scattered small punctures and occasionally a faint impressed median line; metanotum smooth in middle, irregularly rugulose laterally; stigmal fovea small, circular; propodeal enclosure with radiating rugae on basal section, elsewhere rugosoreticulate; area adjacent to enclosure varying from mostly obliquely rugose with a small smooth area posteriorly to obliquely rugose only anterolaterally and with a larger smooth area posteriorly (Figures 38, 39); posterior surface below enclosure irregularly rugosoreticulate; lateral surface obliquely rugulose.

Abdominal petiole (Figures 48, 49) slender, 7.5–8.0 times as long as median width, laterally ecarinate or with a few weak carinae; pygidium depressed, oval, delicately shagreened.

MALE.—Length 4.3–5.3 mm. Black, glossy except vertical surface of face, and clypeus rarely slightly dull from shagreening on base, pronotal lobe white or ivory; specimens with the fewest testaceous areas have the following so colored: palpi, mandible except base and apex, underside of scape and pedicel, tegula, underside of coxae beneath, trochanters, underside of fore femur at base, fore and mid tibiae, and tarsi; specimens with the most testaceous areas have the following so colored: palpi, mandible except base and apex, scape and pedicel entirely, underside of flagellum, tegula, underside of coxae, trochanters, fore and mid femora, tibiae and tarsi, and base of hind tibia; some of apical abdominal sterna light brown in a few specimens. Wings clear, stigma black, veins dark brown.

Head from above (Figure 16) more strongly narrowed behind eyes than in female, width at occiput half greatest width; eyes diverging above more strongly than in female (cf. Figures 3, 26), interocular distance at anterior ocellus 1.8 times that at antennal insertions; clypeus usually glossy, sometimes delicately shagreened on base, clypeal lobe shaped as in female except surface flatter, not so convex; labrum variable in shape, sometimes subpentagonal, sometimes with apical margin subtruncate and broader; frontal ridge strong, present only on vertical surface, projection near middle weaker than in female; ocular groove as in female; vertical surface of face shagreened, weakly, obliquely to transversely wrinkled in part; upper horizontal section of front and vertex sculptured as in female; first four flagellar segments subequal in length; occipital groove narrower and more weakly crenulate than in C. griphus; underside of head as in female, the lateral rugae well developed or evanescent (Figure 24).

Thorax similar in sculpture to that of female and similarly variable in comparative strength and extent of ridges and rugosoreticulations.

Abdominal petiole 6.9–8.3 times as long as median width, similar to that of female in presence or absence of weak carinae laterally; seventh tergum with lateral brush of hairs shorter than in C. costatus.

SPECIMENS EXAMINED (all collected by Krombein et al., USNM, except when specified otherwise).—NORTH CENTRAL PROVINCE. Anuradhapura District: 1, 2 , Padaviya (including archeological site), 180 ft (55 m), 16–19 May (2) and 11–14 Oct (); 5, 8, Ritigala Natural Reserve, 24–25 Feb (5, 7) and 19 Sep (); 1, Mihintale, scrub forest, 20 Sep, Chandler (London).

EASTERN PROVINCE. Trincomalee District: 4, 1, China Bay Ridge Bungalow, 25–50 ft (8–15 m) and 0–100 ft (0–31 m), 26 Feb (4) and 13–17 May (). Amparai District: 1, 1, Lahugala Sanctuary, 13–15 Jun; 2, Ekgal Aru Sanctuary Jungle, 100 m, 19–22 Feb and 12 Jun; 1, Inginiyagala, 10 Jun.

CENTRAL PROVINCE. Matale District: 1, 2, Kibissa jungle, 0.5 mi (805 m) W Sigiriya, 1–3 Mar () in Malaise trap and 28 Jun–4 Jul (, ) in Malaise trap. Kandy District: 1, Teldeniya, Bambaragala Rock, 10 May (P.B. Karunaratne et al.); 1, Woodside, Urugala, 16 Sep (Henry, Colombo); 28, 8, Thawalamtenne, 2200 ft or 740–760 m, 12–13 Mar (4, 3), 21 Mar (, ) 25 Mar (), 4 Sep (4, ), 7–8 Sep (10, 3), 16–18 Sep (8); 109, 18, Kandy (includes Udawattakele Sanctuary, 1800–2100 ft (549–640 m), Reservoir Jungle, Roseneath), 10 Jan (4, 4), 18–21 Jan (), 8–11 Feb (28), 9–13 Feb (12, 2), 10 Feb (2), 4 Mar (), 25 Mar (, Spangler et al.), 26–30 Mar (3), Mar (, Krauss), 25–27 Apr (4), 8–11 May (3), 29–30 May (5), 3–5 Jun (), 5–15 Jul (6, S. Karunaratne), 20–30 Jul (9, 2, S. Karunaratne), 26–30 Jul (5, 5), 16–31 Aug (, S. Karunaratne), Aug (, Krauss), 1–3 Sep (14, 2), 8–10 Sep (2), 21–22 Sep (3), 1–3 Oct ( in black light trap), 27–28 Oct (, S. Karunaratne), Oct (, Krauss), 29 Nov (, Henry, Colombo); 3, 4, Peradeniya, Mahaweli River, 5 mi (8 km) SW Kandy, 22–24 Feb (2, , Stubbs et al., London), 15 Mar (, , Brinck et al., Lund), 30 Dec (2, Uzel, London); 3, 10 km W Kandy, 25 Feb (Sedlacek et al., Honolulu). Nuwara Eliya District: 1, Hakgala Botanical Gardens, 6000 ft (1829 m), 6–8 Oct (Hevel et al.); 2, 1, Diyagama West, 8 mi (12.9 km) S Nuwara Eliya, at 4800 ft (1463 m), 19 Mar (Brinck et al., Lund).

NORTH WESTERN PROVINCE. Kurunegala District: 8, 8, Kurunegala, Badagamuwa Jungle, 24–27 Jan (4), 25 Jan (, 12575A), 20 Sep (3, 8); 1, 1, Kurunegala, 25–26 Jan.

WESTERN PROVINCE. Colombo District: 9, 2, Labugama Reservoir Jungle, 24 mi (39 km) ESE Colombo, 400 ft (122 m), 21 Jan (2, 2, Brinck et al., Lund), 2–4 Feb (3), 16 Feb (), 9 May (), 2–3 Oct (1, Hevel et al.), 13–14 Oct (); 2, Godagama, 25 Oct (Robinson et al.); 1, Padukka, Arakawila Jungle, 26 Nov (P. B. Karunaratne); 6, 3, Colombo (includes Museum Gardens), 11–12 Feb (, Stubbs et al., London), 24 Mar (, Henry, Colombo), 16 Apr (, Halstead, San Francisco), 24–28 Apr (, P.B. Karunaratne), 2 Jul (, P.B. Karunaratne, Ottawa), 7 Jul (, Wijesinhe), 14 Aug (, Colombo), 5 Sep (, P.B. Karunaratne, Ottawa), 22 Sep (, Henry, Colombo); 3, Mirigama Scout Camp, primary jungle, 8–9 Jul; 6, 10, Gampaha Botanical Garden, 14 Jan (, 6), 28 Jan (2), 4 Mar (2), 8 Sep (4), 27 Sep (); 1, Kohuwala, 4 Oct (P.B. Karunaratne, Ottawa); 1, Narahenpitiya District Agricultural Extension Office, 22 Jul (Halstead, San Francisco); 1, Boralesgomuwa, 17 Feb (Stubbs et al., London). Kalutara District: 5, Alutgama, 16 Feb (4, Stubbs et al., London), 3 Mar (, in mangrove swamp, Chandler, London).

SABARAGAMUWA PROVINCE. Kegalla District: 5, Kitulgala, Bandarakele, 180–210 m, 3–4 Feb (3), 25–26 Oct (2). Ratnapura District: 2, Uggalkaltota, 23–26 Jun; 1, 3, Ratnapura, Pompakele, 25 Mar (2), 10 Oct (, ); 1, Panamure, 500 ft (154 m), 15–21 Oct (Flint et al.); 2, Belihuloya Resthouse, 10–11 Apr (Hubbard et al.); 1, 4, Kuruwita, Eratne, Adams Peak Trail, 1 in Malaise trap, 1 Feb; 3, 6, Sinharaja Jungle, 1 in Malaise trap, 8–9 Sep (P.B. Karunaratne et al.); 22, 36, 2–3 mi (3–5 km) S Weddagala, Sinharaja Jungle, 250–490 m, 10, 20 on foliage of Macaranga digyna, 8–12 Feb (11, 17), 13–15 Mar (), 18–21 Jun (5, 13), 22–23 Sep (5, 6); 17, 8, Gilimale, Induruwa Jungle, 6 mi (10 km) NE Raptnapura, 115–300 ft (35–91 m), 3 in Malaise trap, 2 Feb (3, 2), 5–7 Feb (), 20 Feb (, Brinck et al., Lund), 7–8 Mar (6, 2), 13–15 Mar (, ), 26 Mar (2), 3 Apr (, ), 16–19 Apr (), 17 Jun (), 10 Oct (), 22–24 Oct (); 2, 1, Bulutota Pass, 2 mi (3 km) SE Rakwana, 28 Feb (Brinck et al., Lund).

UVA PROVINCE. Badulla District: 1, Beauvais, 5 mi (8 km) WNW Haputale, 4500 ft (1372 m), 3 Mar (Brinck et al., Lund); 1, Heda Oya, 29 mi (47 km) SE Bibile, 7 Mar (Brinck et al., Lund); 1, Egodapitiya Nilgala, 1–13 Jul (P.B. Karunaratne et al., San Francisco); 1, Bibile, Agricultural Research Station, 21 Aug, among aphids on orange tree, Winney (London). Monaragala District: 1, Wellawaya, 10 Aug; 1, 6, Mau Aru, 12 mi (19 km) E Uda Walawe, 17–19 Jun (, 5), 24–26 Sep (); 13, 21, Angunakolapelessa, 100 m, 4, in Malaise trap, 21–23 Jan (7, 9), 27–28 Mar (2), 17–19 Jun (2, 6) 30 Sep–1 Oct (6), 8–9 Oct (2).

SOUTHERN PROVINCE. Galle District: 8, 6, Sinharaja Jungle, Kanneliya section, 400 ft (122 m), 11–16 Jan (2, ), 13–16 Jul (), 2–5 Oct (3, 2), 6–13 Oct (2, 3); 1, Udugama, 14 Feb (Stubbs et al., London). Matara District: 1, Enselwatte, ca. 1500 ft (457 m), 19–20 Oct (Hevel et al.). Hambantota District: 1, Palatupana Tank, 21–22 Jun, in Malaise trap.

MISCELLANEOUS. 3, 1, no locality label (London; syntype series of S. congruus Walker); 2, Ceylon (Moscow; syntype series of S. niger Motshulsky); 6 (London); Ceylon, Thwaites, accession 1867–25 (London); 1, no label (Colombo).