Trissolcus stoicus (Nixon)

Talamas, Elijah J., Buffington, Matthew L. & Hoelmer, Kim, 2017, Revision of Palearctic Trissolcus Ashmead (Hymenoptera, Scelionidae), Journal of Hymenoptera Research 56, pp. 3-185 : 60-62

Trissolcus stoicus (Nixon) Figures 184 , 185-188

Microphanurus stoicus Nixon, 1938: 124, 135 (original description, keyed); Nixon, 1943: 138 (keyed); Risbec, 1950: 569 (keyed).

Trissolcus stoicus (Nixon): Masner, 1965: 128 (type information, generic transfer).

Telenomus stoicus (Nixon): Lê, 1981: 13 (generic transfer, keyed).

Description.

Female body length: 0.93-1.11 mm (n=2). Body color: head, mesosoma, and metasoma black.

Head. Color of radicle: yellow. Length of radicle: less than width of clypeus. Color of A1-A6 in female: yellow. Color of A7-A11 in female: pale brown; yellow, becoming darker distally. Number of basiconic sensilla on A6: 0. Number of basiconic sensilla on A7: 2. Facial striae: absent. Number of clypeal setae: 6. Microsculpture on gena directly above mandibular condyle: absent. Shape of ventral gena in lateral view: narrow. Genal carina: present and extending dorsally to vicinity of lower margin eye. Malar striae: absent. Orbital furrow: expanding in size ventrally, strongly so at intersection with malar sulcus. Macrosculpture of frons between antennal scrobe and anterior ocellus: weakly transversely strigose. Preocellar pit: absent. Setation of lateral frons: moderately dense. Punctation of lateral frons: absent. Macrosculpture of lateral frons: weakly horizontally striate, striae of antennal scrobe extending to lateral frons. OOL: lateral ocellus and eye without continuous scleritic separation. Hyperoccipital carina: complete. Macrosculpture of posterior vertex: absent. Microsculpture on posterior vertex along occipital carina: present medially, absent laterally. Anterior margin of occipital carina: finely crenulate to smooth.

Mesosoma. Epomial carina: present. Netrion sulcus: incomplete. Pronotal suprahumeral sulcus in posterior half of pronotum: clearly indicated by cells. Location of pronotal suprahumeral sulcus: posterior half of pronotum. Number of episternal foveae: 4 or more. Course of episternal foveae ventrally: abutting postacetabular sulcus. Course of episternal foveae dorsally: extending to mesopleural pit. Subacropleural sulcus: present. Speculum: dorsoventrally bisected by deep furrow. Mesopleural pit: extending ventrally into dorsoventral furrow parallel to mesopleural carina. Mesopleural carina: complete. Sculpture of femoral depression: rugulose and pustulate along ventral half of mesopleural carina. Patch of striae at posteroventral end of femoral depression: absent. Setal patch at posteroventral end of femoral depression: absent. Microsculpture of anteroventral mesopleuron: present throughout. Macrosculpture of anteroventral mesopleuron: coarsely rugose. Postacetabular sulcus: formed by open crenulae. Mesopleural epicoxal sulcus: formed by open crenulae. Setation of posteroventral metapleuron: present. Sculpture of dorsal metapleural area: cells of metapleural sulcus extending posteriorly into rugae. Posterodorsal metapleural sulcus: poorly defined to absent. Paracoxal sulcus in ventral half of metapleuron: indicated by a line of elongate cells. Anteroventral extension of metapleuron: not extending to base of mesocoxa. Metapleural epicoxal sulcus: present as coarse rugae. Mesoscutal humeral sulcus: indicated by a line of cells. Median mesoscutal carina: present. Macrosculpture of mesoscutum: coarsely areolate. Pattern of mesoscutal microsculpture: uniform throughout. Mesoscutal suprahumeral sulcus: comprised of cells. Length of mesoscutal suprahumeral sulcus: about half the length of anterolateral edge of mesoscutum. Notaulus: absent; indicated only at posterior margin of mesoscutum. Shape of dorsal margin of anterior lobe of axillar crescent: round. Sculpture of anterior lobe of axillar crescent: dorsoventrally strigose. Area bounded by axillar crescent: smooth. Macrosculpture of mesoscutellum: rugose throughout. Microsculpture on mesoscutellum: present throughout. Median mesoscutellar carina: absent; present. Setation of posterior scutellar sulcus: present. Form of metascutellum: single row of cells. Metanotal trough: mostly smooth, with furrow along ventral margin. Metapostnotum: invaginated near lateral edge of metascutellum. Length of postmarginal vein: about 1.5 times as long as stigmal vein. Color of legs: coxae dark brown to black, trochanters and femora yellow to brown, elsewhere yellow to orange. Anteromedial portion of metasomal depression: antero-posteriorly striate.

Metasoma. Longitudinal striae on T1 posterior to basal costae: present. Number of sublateral setae (on one side): 0. Setation of laterotergite 1: present. Longitudinal striation of T2: present laterally, absent medially. Setation of T2: present at posterior termination of striae. Setation of laterotergite 2: present. Posteriorly directed setae on medial S1: present. Striation of S2: present laterally and in anterior half of median third. Setation of S2: present posteromedially.

Diagnosis.

Trissolcus stoicus can be distinguished from most species treated here by having 6 clypeal setae and a complete hyperoccipital carina, a combination which is otherwise known to us only from T. carinifrons . These are otherwise dissimilar species and can be separated by the sculpture of the gena (coarse in T. carinifrons and smooth in T. stoicus ) and the shape of the foveae that form the mesepimeral sulcus (circular in T. carinifrons and elongate in T. stoicus ). The form of the metanotal trough, in which the cells are present at the bottom of a narrow furrow is shared with T. exerrandus , from which it may separated by the presence of dense setation on the eyes in the latter. The distribution of striae on T2 in T. stoicus , in which striae are present laterally and absent medially, is unusual for Trissolcus , at least in our experience. However, this character is not fully visible in the holotype specimen and we are thus hesitant to use it for identification with a sample size of only three specimens, particularly when a wealth of other characters exists to identify this species.

Link to distribution map.

http://hol.osu.edu/map-large.html?id=3312

Associations.

emerged from egg of Coffea Linnaeus: [ Rubiales : Rubiaceae ]; emerged from egg of Hemiptera : [ Hemiptera ]; emerged from egg of Lepidoptera : [ Lepidoptera ]

Material examined.

Lectotype, female, M. stoicus : MALAYSIA: Pahang St., Malay Peninsula , Pahang, 16.VI.1932, G. H. Corbett, B.M. TYPE HYM. 9.314 (deposited in BMNH). MALAYSIA: 1 female, UCRC ENT 297004 (UCRC). THAILAND: 1 female, OSUC285262 (OSUC).

Lectotype designation.

We here designate specimen B.M. TYPE HYM. 9.314 (deposited in BMNH) to be the lectotype of this species.

Comments.

Trissolcus stoicus exhibits two characters that suggest in may be an intermediate form between the flavipes and thyantae species groups. The hyperoccipital carina and setation of the first laterotergite ally it with the flavipes group. However, the presence of 6 clypeal setae and 2 large setae in the posteroventral metapleuron suggest relation to the thyantae group.

Figures

Figure 184. Trissolcus stoicus, female (OSUC 285262), head, mesosoma, metasoma, dorsal view. Scale bar in millimeters.

Figures 185 - 188. Trissolcus stoicus 185 female holotype (B. M. TYPE HYM. 9.314), head and mesosoma, lateral view 186 female holotype (B. M. TYPE HYM. 9.314), head and mesosoma, dorsolateral view 187 female (OSUC 285262), mesosoma, posterolateral view 188 female (OSUC 285262), head, anterior view. Scale bars in millimeters.