Trissolcus siliangae Yan, Chen & Talamas, 2022

Yan, Cheng-Jin, Talamas, Elijah, Lahey, Zachary & Chen, Hua-Yan, 2022, Protelenomus Kieffer is a derived lineage of Trissolcus Ashmead (Hymenoptera, Scelionidae), with comments on the evolution of phoresy in Scelionidae, Journal of Hymenoptera Research 94, pp. 121-137 : 121

Trissolcus siliangae Yan, Chen & Talamas sp. nov.

Figs 1 , 2 , 3 , 4

Description.

Female body length: 1.28 mm (n = 4). Body color: head, mesosoma, and metasoma black, shining. Mandible color: red-brown. Leg color: coxae and tarsi dark brown, rest of legs yellow-brown. Tegulae yellow-brown. Antennal color: radicle and A1-A2 yellow to brown, darker dorsally; A3-A11 dark brown.

Head. Length of radicle: less than width of clypeus. Claval formula: A8-A11:1-1-1-1. Facial striae: present. Number of clypeal setae: 4. Shape of gena in lateral view: moderately wide, bulging. Genal carina: absent. Malar striae: absent. Sculpture of malar sulcus: smooth. Orbital furrow: expanded at intersection with malar sulcus, medial margin of furrow poorly defined. Macrosculpture of frons directly dorsal to the antennal scrobe: absent. Preocellar pit: absent. Setation of lateral frons: sparse. Punctation of lateral frons: absent. Sculpture directly ventral to preocellar pit: coriaceous microsculpture. Rugae on lateral frons: absent. OOL: about one ocellar diameter. Hyperoccipital carina: absent. Macrosculpture of posterior vertex: absent. Microsculpture on posterior vertex along occipital carina: coriaceous. Anterior margin of occipital carina: crenulate. Medial part of occipital carina in dorsal view: rounded.

Mesosoma. Epomial carina: present. Macrosculpture of lateral pronotum directly anterior to netrion: finely rugulose. Netrion sulcus: incomplete, only weakly defined ventrally. Pronotal suprahumeral sulcus in posterior half of pronotum: absent. Number of episternal foveae: 2. Course of episternal foveae ventrally: abutting dorsal apex of acetabular carina. Course of episternal foveae dorsally: distinctly separate from mesopleural pit. Subacropleural sulcus: present. Speculum: transversely strigose. Mesopleural pit: simple. Mesopleural carina: absent. Sculpture of femoral depression: smooth. Patch of striae at posteroventral end of femoral depression: present, striae orthogonal to long axis of femoral depression. Setal patch at posteroventral end of femoral depression: present as a line of setae. Microsculpture of anteroventral mesopleuron: present in anterior portion, smooth posteriorly. Macrosculpture of anteroventral mesopleuron: absent. Postacetabular sulcus: present as a smooth furrow. Mesopleural epicoxal sulcus: indicated by shallow foveae. Setation of posteroventral metapleuron: absent. Sculpture of dorsal metapleural area: rugulose. Posterodorsal metapleural sulcus: undifferentiated. Paracoxal sulcus in ventral half of metapleuron: absent. Length of anteroventral extension of metapleuron: short, not reaching base of mesocoxa. Metapleural epicoxal sulcus: indistinguishable from rugose sculpture. Mesoscutal humeral sulcus: comprised of shallow foveae. Median mesoscutal carina: absent. Microsculpture of mesoscutum: coriaceous. Mesoscutal suprahumeral sulcus: comprised of shallow foveae. Length of mesoscutal suprahumeral sulcus: about two-thirds the length of anterolateral edge of mesoscutum. Parapsidal line: present. Notaulus: absent. Median protuberance on anterior margin of mesoscutellum: absent. Shape of dorsal margin of anterior lobe of axillar crescent: flat. Sculpture of anterior lobe of axillar crescent: dorsoventrally strigose. Area bound by axillar crescent: smooth. Macrosculpture of mesoscutellum: absent. Microsculpture on mesoscutellum: coriaceous. Median mesoscutellar carina: absent. Setation of posterior scutellar sulcus: absent. Form of metascutellum: broad, short, rugose projection. Metanotal trough: foveate, foveae occupying less than half of metanotal height. Metapostnotum: invaginated laterally, propodeum and metanotum directly adjacent. Anteromedial portion of metasomal depression: rugulose.

Wings. Length of postmarginal vein: about twice as long as stigmal vein. Fore wing apex: reaching beyond T6.

Legs. Color: coxae and distal tarsomeres dark brown to black, otherwise yellow to light brown. Anteroventral area of hind femora: not covered by setae. Femur and tibia not enlarged. Basitarsi of fore leg with a row of densely stout bristles at basal half. Claws well developed, curved.

Metasoma. Width of metasoma: about equal to width of mesosoma. Longitudinal striae on T1 posterior to basal costae: present. Number of sublateral setae (on one side): 0. Setation of laterotergite 1: absent. Striation on T2: extending about half the length of the tergite, weakly indicated. Setation of T2: present along lateral margin. Setation of laterotergite 2: present. Striation on S2 striate: present laterally, length of striae extending up to anterior half, remainder smooth. S2 felt fields: present. Sculpture of S3-S6: setigerous punctate.

Male. Unknown.

Diagnosis.

Moniliform antennae in females are rare in Scelionidae , shared in Trissolcus by T. siliangae , T. flavicornis , T. gajadanta , and T. planus ; these species also have a single papillary sensillum on each clavomere. Care should be taken to count the antennomeres (11 in females, 12 in males) so that female specimens are not mistaken for males. Clavomeres that are only slightly wider than the preceding flagellomeres are more common, found in many species of the former Protelenomus and in more typical Trissolcus such as T. sipioides .

Trissolcus siliangae has a laterally invaginated metapostnotum, as in T. hullensis ( Johnson 1985), which is found in a minority of Trissolcus species. In Veenakumari et al. (2019), the metapostnotum in T. flavicornis appears to extend medially, separating the propodeum from the metanotum until it reaches the vicinity of the lateral margin of the metascutellum (see figures 27, 29, and 31 of that publication). We find this to be the case for T. gajadanta as well, based on examination of a specimen from Ivory Coast (Fig. 5 ). Trissolcus siliangae can thus be separated by the combination of the moniliform antennae, claval formula (1-1-1-1), and lateral invagination of the metapostnotum. Additionally, T. siliangae can be separated from the very similar T. gajadanta by the striation on T2: robust in the anterior ⅔ of the tergite in T. gajadanta and only weakly present in T. siliangae ; and by the robust parapsidal lines in T. gajadanta , which are not indicated in T. siliangae . Notably, the posterior head in T. gajadanta has two concavities lateral to a dorsoventral median ridge, with the dorsal part of the occipital carina located low on the posterior head (Fig. 5B ).

Etymology.

This species is named after one of its collectors, Dr. Siliang Wang, for her discovery of this species.

Material examined.

Holotype, female: China: Zhejiang, Wenzhou, corn field, 27.609301°N, 120.508985°E, phoretic on Cletus punctiger Dallas , 10.IX.2021, Cheng-jin Yan, SCAU 3042644 (deposited in SCBG) . Paratypes: (3 females) China: 2 females , same data as holotype, SCAU 3042799, 3041198 (SCBG); 1 female , China: Zhejiang, Wenzhou , corn field, 27.609301°N, 120.508985°E, phoretic on Cletus punctiger Dallas, 10.IX.2021, Siliang Wang, SCAU 3044000 (WVCST) .

Distribution.

China (Zhejiang).

Figures

Figure 1. A female Trissolcus siliangae on Cletus punctiger B closeup of T. siliangae on C. punctiger from Fig. 1 A.

Figure 2. Trissolcus siliangae, paratype, female (SCAU 3042799) A dorsal habitus B lateral habitus C head and mesosoma, dorsal view D head and mesosoma, lateral view E head, anterior view F metasoma, dorsal view G antenna H fore wing.

Figure 3. Trissolcus siliangae, paratype, female (SCAU 3042799) A antenna B apical antennal segments A head, anterior view D head, dorsal view E head, ventral view F mesosoma, lateral view G metasoma, dorsal view H metasoma, ventral view.

Figure 4. Trissolcus siliangae, paratype, female (SCAU 3042799) A mesosoma, dorsal view B dorsal mesopleuron, lateral view.

Figure 5. Trissolcus gajadanta, female (398371) A head, mesosoma, metasoma, dorsolateral view B head and mesosoma, posterolateral view C head, anterior view D head, mesosoma, metasoma, lateral view.