Synopeas ruficoxum Buhl, 2006

von Gries, Sarah C., Awad, Jessica, Talamas, Elijah J., McMechan, Anthony J., Koch, Robert L. & Lindsey, Amelia R. I., 2025, Synopeas ruficoxum Buhl (Hymenoptera, Platygastridae) is a natural enemy of soybean gall midge, Resseliella maxima Gagné (Diptera, Cecidomyiidae), Journal of Hymenoptera Research 98, pp. 721-742 : 721-742

Synopeas ruficoxum Buhl

Figs 4 , 5

Synopeas ruficoxa Buhl, 2006: 203, figs 38–41 (original description).

Synopeas ruficoxum Buhl : von Gries et al. 2025 (mandatory change).

Description.

Females. Body length: 1.7–2.1 mm (n = 10). Body color: black. Color of legs: coxae brown, otherwise yellow to brown. Color of mesoscutellar spine: concolorous with mesoscutellar disc.

Head. Shape of head in anterior view: round to ovoid (Fig. 4 A ). Central keel: absent; present only between toruli. Sculpture on frons: reticulate microsculpture. Epitorular sculpture: reticulate microsculpture; minute rugulae. Number of clypeal setae: 4. Length of median pair of clypeal setae: longer than lateral pair. Arrangement of clypeal setae: median pair closer to each other than to lateral setae. Shape of mandible: bidentate. Distance between lateral ocellus and compound eye (OOL): greater than 1 ocellar diameter. OOL: LOL: 1: 1; 1: 1.2. Lateral ocellar depression: present posterolaterally. Hyperoccipital carina: absent or only faintly suggested medially. Hyperoccipital carina strength: indicated as sharp angle of vertex between lateral ocelli. Distance between lateral ocellus and hyperoccipital carina: greater than 1 ocellar diameter. Claval formula: 1-1 - 1 - 1.

Mesosoma. Epomial carina: present, complete, or nearly so. Pronotal cervical sulcus: smooth, glabrous. Anterior pronotal pit: present. Ventral pronotal pit: setose. Microsculpture of lateral pronotum: present anterodorsally, absent posteroventrally. Lateral pronotal sculpture coverage: 1 / 3–1 / 2. Setation of lateral pronotum: anteroventrally glabrous, otherwise uniformly sparse (Fig. 4 B ). Mesoscutellar spine: short to moderately developed and pointed. Mesoscutellar spine in lateral view: pointing posteriorly, often with slight downcurve at tip. Origin of mesoscutellar spine: slightly below dorsal apex of mesoscutellum. Posterior margin of propodeal carina in lateral view: rounded. Mesosomal dorsum in lateral view: slightly convex. Scuto-scutellar sulcus: shallow, mesoscutum not elevated relative to mesoscutellum. Notauli: percurrent. Parapsidal line: indicated. Setation of mesoscutum: sparse. Mesoscutal lamella: short, truncate. Setation of mesoscutellum: sparse to absent, denser along posterior margin. Setal patch of dorsolateral hind coxa: present, long, extending dorsally to level of felt field.

Metasoma. Sculpture of T 2: faintly sculptured in posterior corners. Length of T 2: conspicuously shorter than mesosoma. Sculpture of T 3 to T 5: reticulate. Sculpture of T 6: entirely reticulate. Shape of T 6: triangular, 2.5 times as long as wide. Microsculpture of S 2: sculptured in posterior 1 / 3. Shape of S 2: slightly expanded ventrally. Sculpture of S 3 to S 5: reticulate. Shape of S 3: trapezoidal, approximately as wide as long. Shape of S 4: more than twice as long as wide. Shape of S 5: approximately twice as long as wide. Sculpture of S 6: entirely reticulate.

Wing. Length of setae on disc of fore wing: much shorter than distance between setal bases. Density of setae on disc of fore wing: sparse. Arrangement of setae on disc of fore wing: uniformly setose distally, proximally sparser. Fore wing marginal setae: uniformly very short.

Males. Unknown.

Diagnosis.

Synopeas ruficoxum and S. craterum have distinctly elongate T 4 and T 5, both at least twice as long as wide (Figs 4 C, D ), as opposed to S. abdominator and S. zaitama , in which T 4 is only slightly longer than wide. In S. ruficoxum , the mesoscutellar spine is well-developed, originating below the dorsal apex of the mesoscutellum, and points posteriorly, often with a downward curve at the tip. This sets it apart from S. craterum , which has a very short spine originating at the dorsal apex of the mesoscutellum, and from S. abdominator , in which the short, straight spine is angled posterodorsally. The posterior half of the lateral pronotum is smooth in S. ruficoxum , whereas it is sculptured in S. zaitama . The sculpture of the ventral metasoma is more extensive in S. ruficoxum than in S. abdominator , which has no sculpture on S 6.

Remarks.

The original description compared S. ruficoxum to S. auripes ( Ashmead, 1893) and S. ashmeadii Dalla Torre, 1898 , neither of which shares its metasomal structure. Such comparisons are of little relevance and demonstrate the importance of examining specimens rather than relying solely on written descriptions. This is particularly relevant for very old descriptions because many authors provided too little detail for accurate diagnosis, and there may even be significant errors in the provided text and illustrations.

The species epithet refers to the color of the coxae, which tend to be much lighter than the rest of the body (Fig. 5 A, B ). However, in some specimens the coxae are dark brown and the appendages are darker overall (Fig. 5 C ). Coloration can be altered by specimen age and preservation history, and also exhibits natural variation in many species. Due to this variability, coloration is not a reliable diagnostic character for most Synopeas species.

Material examined.

Synopeas ruficoxum Buhl , holotype female, NHMD 918361 , Canada, New Brunswick, Carleton Co, Meduxnekeag River (near Belleville) 46.11354 ° N, 67.40556 ° W 10–15. VII. 2005 Malaise trap 2 J. Bonet, M. Forshage, R. Hovmöller ( ZMUC) . Other material: 28 females, USA: Nebraska, FSCA 00033404 –00033407 ( CNCI); FSCA 00033408 –00033411 ( USNM); FSCA 00033412 –00033419 ( UMSP); FSCA 00033420 –00033428, 00034119 ( FSCA); BOLD Vouchers: BIOUG 32277 -G 12, BIOUG 26568 -F 09 . The list of materials examined is also provided in Table 1 .

Figures

Figure 4. Synopeas ruficoxum (FSCA 00033423) A head, anterior view B head and pronotum, lateral view C habitus, dorsolateral view D habitus, dorsal view.

Figures 5. Synopeas ruficoxum, lateral view A holotype, New Brunswick, Canada (NHMD 918361) B Guelph, Ontario, Canada 2017 (BIOUG 26568 - F 09; accession number MG 346361) C Nebraska, USA 2021 (FSCA 00034119).