Sesioctonus^{Viereck, 1912}

^{Viereck 1912}:1. Type species: Sesioctonus parathyridis Viereck. (Monobasic and original designation). Viereck 1914: 133.

Diagnosis. Sesioctonus species may be distinguished from other agathidines using the following combination of characters: Mesoscutum smooth, lacking notauli; tarsal claws simple, lacking a distinctive basal claw; hind coxal cavities open, sharing a common opening with the metasomal foramen.

Distribution. Members of Sesioctonus are restricted to the Neotropical Region.

List of all Sesioctonus species described

Sesioctonus acrolophus^{Briceño, 2003}; S. alvaradae sp. nov; S. amazonensis Briceño, 2003; S. ammosakron Briceño, 2003; S. analogus Briceño, 2003; S. areolatus Briceño, 2003; S. ariasi Briceño, 2003; S. armandoi Briceño, 2003; S. bina^{Sulca & Sharkey, 2012}; S. biospleres Briceño, 2003; S. boliviensis Briceño, 2003; S. brasiliensis Briceño, 2003; S. chaconi Briceño, 2003; S. chrestos Briceño, 2003; S. clavijoi Briceño, 2003; S. diazi Briceño, 2003; S. dichromus Briceño, 2003; S. dominions Briceño, 2003; S. eumenetes Briceño, 2003; S. galeos Briceño, 2003; S. garciai Briceño, 2003; S. grandis Briceño, 2003; S. huggerti Sulca & Sharkey, 2012; S. kompsos Briceño, 2003; S. longinoi Sharkey & Briceño, 2005; S. miyayensis Briceño, 2003; S. parathyridis^{Viereck, 1912}; S. peruviensis Briceño, 2003; S. philipi Sharkey & Briceño, 2005; S. qui Briceño, 2003; S. theskelos Briceño, 2003; S. venezuelensis Briceño, 2003; S. torresi Sharkey & Briceño, 2005; S. stephaniai Sharkey & Briceño, 2005; S. susanai Sharkey & Briceño, 2005 and S. wayquecha Sulca & Sharkey, 2012.

Key to Sesioctonus species of the world modified from ^{Sulca & Sharkey (2012})

1. Occipital tubercles present (Figs. 16B-18B) 2

― Occipital tubercles absent. (Figs. 19B)17

2(1). Epicnemial carina straight medially or absent, not indented at midline, between forecoxae) (Figs. 4B, 23B) 3

― Epicnemial carina bilobed medially, (indented at midline, between forecoxae) (Figs. 3B, 22B)6

3(2) Epicnemial carina complete laterally (Figs. 3B, 22B) 4

― Epicnemial carina incomplete or absent laterally (Fig. 23B) 5

4(3) Interantennal space with longitudinal rounded keel, face without median longitudinal carinae garciai Briceño

― Interantennal space lack of longitudinal keel, face with median longitudinal carinae huggertii Sulca & Sharkey

5(3) Face with median longitudinal carina (Fig. 13B) acrolophus Briceño

― Face without median longitudinal carina (similar to Figs. 12B,14B) analogus Briceño

6(3) Midcoxa not completely melanic, color variable7

― Midcoxa completely melanic10

7(6) Forewing banded from base: yellow, black, yellow, black chaconi Briceño

― Forewing infuscate (melanic)8

8(7) Fore tibias with spines; mid femur yellowish orange 9

― Fore tibia without spines; mid femur melanic longinoi (part) Sharkey & Briceño

9(8) Median longitudinal carinae of propodeum absent, median areola of metanotum and with lateral carinae not meeting posteriorly, subpronope triangular peruviensis Briceño

― Median longitudinal carinae of propodeum present, median areola of metanotum and with lateral carinae meeting posteriorly, subpronope oval bina Sulca & Sharkey

10(6) Longitudinal carina(e) of scutellar depression present and forewing banded from base: yellow, black, yellow, black venezuelensis Briceño

― Longitudinal carina(e) of scutellar depression absent and/or forewing not banded11

11(10) Mesoscutum black; median areola of metanotum with longitudinal rugosities (Fig. 29B); median tergite of first metasomal segment without pair of lateral longitudinal carinae (similar to Fig. 34B); forewing (RS+M)a vein complete (Fig. 10B) kompsos Briceño

― Mesoscutum yellowish orange; or if black then not combining other character12

12(11) Mesoscutum melanic 13

― Mesoscutum yellowish orange14

13(12) Forewing infuscate with large hyaline spot; metasoma reddish brown except last few segments melanic brasiliensis Briceño

― Forewing either infuscate without hyaline spot or hyaline basally, infuscate apically; metasoma yellowish orange dichromus Briceño

14(12) Median longitudinal carina of propodeum present and complete ariasi Briceño

― Median longitudinal carina of propodeum absent or incomplete15

15(14) Subpronope triangular, three sides almost equal (Fig. 1B); forewing 3RSa vein absent (Fig. 10B) boliviensis Briceño

― Subpronope more oval-shaped, weak triangle with vertical sides longer than dorsal side (Fig. 2B); forewing 3RSa vein present (Fig. 9B)16

16(15) Wings banded from base: yellow, black, yellow, black diazi Briceño

― Wings infuscate (melanic) longinoi (part) Sharkey & Briceño

17(1) Occiput excavated (similar to Figs. 16B-18B) 18

― Occiput not excavated (Fig.19B)19

18(17) Propodeum with central areola absent; Epicnemial carina bilobed medially (between forecoxae) (similar to Fig.3B) eumenetes Briceño

― Propodeum with central areola present (Fig.7); Epicnemial carina straight medially (between forecoxae) (Fig.8). alvaradae sp. nov.

19(17) Interantennal space without sharp longitudinal keel 20

― Interantennal space with sharp longitudinal keel (Fig. 11B) 35

20(19) Basal sterna of metasoma chalk-white 21

― Basal sterna of metasoma not chalk-white, rather melanic or yellowish orange 23

21(20) Head orange susanai Sharkey & Briceño

― Head black 22

22(21) Fore and hind coxa pale yellow stephaniai Sharkey & Briceño

― Fore and hind coxa melanic philipi Sharkey & Briceño

23(20) Median areola of metanotum with lateral carinae meeting posteriorly (Figs. 25B, 26B) 24

― Median areola of metanotum with lateral carinae absent or, if present, not meeting posteriorly (Figs. 27B, 28B)33

24(23) Epicnemial carina present (Figs. 3B, 4B) 25

― Epicnemial carina absent 29

25(24) Epicnemial carina complete laterally (Fig. 3B)26

― Epicnemial carina incomplete laterally (Fig. 4B) 31

26(25) Hind tibia melanic amazonensis Briceño

―Hind tibia mostly yellowish orange27

27(26) Propodeum with central areola absent28

― Propodeum with central areola present areolatus Briceño

28(27) Antenna with more than 29 flagellomeres; interantennal space with rounded longitudinal keel (similar to Fig. 12B); hind tibia yellowish orange in basal half, melanic apically miyayensis Briceño

― Antenna with less than 28 flagellomeres; interantennal space without longitudinal keel; hind tibia mostly yellowish orange, melanic apically clavijoi Briceño

29(24) Scutellar depression with longitudinal carinae; body color yellow, white, and black torresi Sharkey & Briceño

― Scutellar depression without longitudinal carinae; body color yellowish orange and black 30

30(29) (RS+M)a vein of forewing complete, median tergite of first metasomal segment with pair of lateral longitudinal carinae ammosakron Briceño

― (RS+M)a vein forewing incomplete, median tergite of first metasomal segment without pair of lateral longitudinal carinae wayquecha Sulca & Sharkey

31(25) Epicnemial carina straight medially (between forecoxae) (Fig. 4B); body length less than 3mm dominicus Briceño

― Epicnemial carina bilobed medially (indented at midline, between forecoxae) (Fig. 3B); body length more than 3mm32

32(31) Forewing (RS+M)a vein complete (Fig. 10B) armandoi Briceño

Forewing (RS+M)a vein incomplete (Fig. 9B) biospleres Briceño

33(23) Epicnemial carina present complete, or incomplete laterally (Figs. 3B, 4B)34

― Epicnemial carina completely absent chrestos Briceño

34(35) Forewing banded, yellow, black, yellow, black; labial palpus 3-segmented galeos Briceño

― Forewing infuscate; labial palpus 4-segmented theskelos Briceño

35(19) Third and fourth labial palpomeres not fused; first metasomal median tergite with depression posterad spiracle (Figs. 36B, 37B) grandis Briceño

― Third and fourth labial palpomeres fused, first metasomal median tergite with or without depression posterad spiracle36

36(35) First metasomal median tergite with depression posterad spiracle (similar to Figs. 3B, 36B) qui Briceño

― First metasomal median tergite without depression posterad spiracle parathyridis Viereck

Sesioctonus alvaradae sp. nov.

(Fig. 1-8)

Holotype. 1♀, PERU: AP [APURIMAC]: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.24’’S/ 72^o18’33’’W, 4265 m, 01.iii.2020, L. Pérez.

Paratype. 3♀, PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.4’’S/ 72^o18’33’’W, 4265 m, 07- 10.xii.2019, L. Pérez; 4♀, PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.4’’S/ 72^o18’33’’W, 4265 m, 20-24. i.2021, R. Angulo; 1♀, PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.4’’S/ 72^o18’33’’W, 4265 m, 03-10.iii.2021, R. Angulo; 2♀, PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.24’’S/ 72^o18’33’’W, 4265 m, 02.x.2020, Y. Nina; 2♀, PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.11’’S/ 72^o18’32.63’’W, 4178 m, 21- 23.ii.2019, L. Pérez; 2♀PERU: AP: Mina Las Bambas, Sector Sagrapeña, 14^o4’37.24’’S/ 72^o18’33’’W, 4265 m, 29.xi-03.xii.2018, L. Pérez; 3♀, PERU: AP: Cotabambas, Challhuahuacho, Pumamarca (Sallahue), 14^o2’56.53’’S/ 72^o19’19’’W, 4291 m, 03-04. iii.2020, N. Zenteno y A. Silva; 1♀, PERU: AP: Cotabambas, Challhuahuacho, Pumamarca (Sallahue), 14^o3’6.1’’S/ 72^o18’39.9’’W, 4201 m, 03-04. iii.2020, N. Zenteno y A. Silva; 1♀, PERU: AP: Cotabambas, CC Antuyo, 14^o4’32.89’’S/ 72^o16’46.25’’W, 4353 m, 6. iii.2020, N. Zenteno y A. Silva; 1 ♀, PERU: AP: Cotabambas, Challhuahuacho, Ferrobamba, 14^o5’18.5’’S/ 72^o20’51.01’’W, 4376 m, N. Zenteno y A. Silva; 1 ♀, PERU: AP: Gran Progreso, 14^o1’30.24’’S/ 72^o26’6.85’’W, 4029 m, 25.vii.2021, N. Zenteno y A. Silva; 1 ♀, PERU: AP: Chalcobamba, 14^o3’38.86’’S/ 72^o20’20.42’’W, 4509 m, 25.viii.2019, L. Perez; 1 ♀, PERU: AP: Cotabambas, Challhuahuacho, Ferrobamba, 14^o3’28.6’’S/ 72^o19’55.72’’W, 4438 m, 17.x.2021, L. Villena; 1 ♀, PERU: AP: Cotabambas, Challhuahuacho, CCPP. Cconchaccota, 14^o11’17.6’’S/ 72^o4’5.4’’W, 4438 m, 12- 13.iii.2015, L. Sulca & I. Medina; 1 ♀, PERU: AP: Cotabambas, Challhuahuacho, CCPP. Ccahuanhuire, 14^o10’34.5’’S/ 72^o23’52.8’’W, 4079m, 13- 14.iii.2015, L. Sulca & I. Medina; 1 ♀, PERU: CU: Paruro, Omacha, 14^o8’26.7’’S/ 71^o53’17.1’’W, 4178m, 1- 5.iii.2022, A. Nuñez; 1 ♀, PERU: CU: Chumbivilca, Uchucarco, 14^o23’29.64’’S/ 71^o47’6.72’’W, 4544m, 16.ix.2022, A. Ayala; 1 ♀, PERU: CU: Espinar, Mina Constancia, 13^o33’54’’S/ 71^o42’41’’W, 4309m, 15-23.ix.2017, L. Huerto.

Diagnosis. Distinguished from all other known species of Sesioctonus by the following combination of characters: occipital tubercles absent, occiput excavated, gena moderately expanded posteroventrally, subpronope elongate-oval, epicnemial carina complete and straight medially, propodeum with a central areola.

Sesioctonus alvaradae sp. nov. is similar to S. eumenetes, as they are the only two species that have an occiput excavated; but the first one has a central areola on the propodeum that is lacking in S. eumenetes.

^{Briceño (2003}) indicates in the S. eumenetes diagnosis the presence of a median longitudinal carina on the propodeum, but contradicts the description indicating absence. I was able to verify the absence of a longitudinal carina by reviewing the photos of the S. eumenetes holotype hosted in the website of the Canadian National Collection ( https://www.cnc.agr.gc.ca/taxonomy/Specimen.php?id=5878).

♀ Length. Length of body, excluding ovipositor, 4.1 mm.

Figures 1 6. Details of Sesioctonus alvaradae sp. nov. Holotype:(1) habitus; (2) head, frontal; (3) head, dorsal; (4), metasomal tergo (5); mesonotum, dorsal; (6) propodeum and metasomal terga 1-2. 

Head. Flagellum with 23 flagellomeres. Interantennal space lacking longitudinal keel. Antennal sockets not excavated. Face without median longitudinal carina. Gena moderately expanded posteroventrally. Occipital tubercles absent. Occiput excavated. Mandible concave, outer tooth of mandible not longer than inner tooth. Maxillary palpus with 4 palpomeres. Third and fourth labial palpomeres not fused. Mesosoma. Subpronope elongate-oval. Longitudinal carinae of scutellar depression absent. Scutellum convex. Median areola of metanotum smooth; without median longitudinal carina; and with lateral carinae meeting posteriorly. Propodeum convex, with a central areola. Epicnemial carina complete, straight medially (between forecoxae). Foretibial spines present. Midtibia with 8 spines. Hind tibia with 8 spines. Hind femur 4 times as long as wide. (RS+M)a vein of forewing incomplete. 3RSa vein of forewing absent. 2-1A vein of hind wing tubular. Cub vein of hind wing absent. Hind wing with 3 hamuli. Metasoma. Median tergite of first metasomal segment with pair of lateral longitudinal carinae. First metasomal median tergite without depression postered spiracle. Length/width ratio of first metasomal median tergite 1.5. Ovipositor 3.7 mm. Color. Head melanic. Antenna melanic. Maxillary palpomeres melanic. Labial palpomeres melanic. Mandible yellowish with melanic teeth. Mesosoma mostly melanic except mesoscutum orangish red with two spots melanic around of tegulae and mesopleuron, anterior scutellum, middle of metapleuron orangish red. Legs mostly melanic except yellowish orange at apical of femur; basal 1/3 melanic and apical 2/3 yellowish orange. Forewing entirely infuscate. Stigma melanic. Hind wing entirely infuscate. First metasomal tergum melanic. Second metasomal tergum yellowish orange. Third metasomal tergum yellowish orange. Fourth metasomal tergum yellowish orange. Fifth and sixth metasomal terga yellowish orange with melanic spot. Seventh and to eighth metasomal terga melanic. Ovipositor yellowish orange.

Figures 7 8. Details of Sesioctonus alvaradae sp. nov. Paratype:(7) Propodeum with central areola present (indicated by arrow); (8) Epicnemial carina straight medially (indicated by arrow). 

Male. As in the female (above) with the color of the metasomal terga slightly different. First metasomal tergum melanic. Second metasomal tergum yellowish orange. Third -to fifth metasomal terga yellowish orange with melanic spot. Sixth and to eighth metasomal terga melanic.

Variation. Legs with variable color, but always melanic to yellow. Sometimes propodeum with a yellow spot medially.

Etymology. Named in honor of Mabel Alvarado, a Peruvian specialist in ichneumonoid wasps, for her support during the author’s entomological studies.

Distribution. Known only from Apurimac and Cusco, in southeastern Peru.