Caradiophyodus saradae, Poinar & Vega, 2023

Poinar, George & Vega, Fernando E., 2023, Caradiophyodidae, a New Family of Micro-Wasps (Hymenoptera: Platygastroidea) Based on the Description of Caradiophyodus saradae gen. et sp. nov. in Mid-Cretaceous Burmese Amber, Life (Basel, Switzerland) 13 (8), pp. 1-13 : 2-6

Type species: Caradiophyodus saradae gen. and sp. nov.

LSID: urn:lsid:zoobank.org:act:C9BD5866-D6E0-4278-B8A3-48C2DAE79CD1 (accessed on 24 July 2023).

The specific epithet is in honor of Dr. Sarada Krishnan for her contributions to coffee genetic resources research. Dr. Krishnan is the Director of Programs at the Global Crop Diversity Trust in Bonn, Germany, and Executive Director of the International Women’s Coffee Alliance.

Holotype: Accession number B-Hy-21 deposited in the Poinar Amber Collection maintained at Oregon State University.

Type locality: Myanmar (Burma), state of Kachin, Noije bum 2001 Summit Site amber mine in the Hukawng Valley , SW of Maingkhwan (26 ◦ 20 0 N, 96 ◦ 36 0 E).

Description: Female. Body (length without antennae 1.3 mm) elongated, black, smooth, non-metallic, and nearly parallel-sided.

Head: Hypognathous; length, 210 µm; width, 277 µm; toruli adjacent; positioned just above oral cavity below level of ventral margin of eyes; much closer to each other than to eyes; length eye, 90 µm; ommatidia stalked; antennae 0.7 mm in length; not elbowed, with 15 segments; ring segments absent; scape short, length 36 µm, pedicel long, length 70 µm, with a ventral flange; first flagellomere fusiform (tapering at both ends), remaining flagellomeres transverse, gradually becoming larger toward apex and terminating in a 7- or 8-segmented clavis; dorsum of head with distinct curved, raised “horseshoe shaped” sclerite along inner margin of eyes, ending just before lateral ocelli, greatest diameter of sclerite, 160 µm; thickness of sclerite, 18 µm; dark subocular sclerite positioned below each eye; length suboptical sclerite, 92 µm; width suboptical sclerite, 53 µm; horizontal cleft extending across head between eyes and subocular sclerites.

Mesosoma: Black, smooth, lacking any metallic colors; length, 625 µm; pronotum extending back to tegulae; length pronotum 280 µm; pronotal carina absent; mesoscutum (length = 107 µm) transversely carinate; with faint ridges possibly incorporating the skaphion; notauli and petiole absent; mesoscutellum (length = 190 µm) squarish; carinate with faint transverse suture, lacking projection or process.

Legs: Femora swollen; similar in size; length, 160 µm; tibia narrow; straight; length metatibia, 140 µm; tibial spur formula 1-1-2; tarsus 5-segmented, basal segment longest, segment lengths (1, 156 µm; 2, 60 µm; 3, 60 µm; 4, 43 µm; 5, 57 µm; pretarsus, 35 µm); tarsal claws paired, pointed; with wide base; aroleum positioned at right angles to the tarsus.

Wings: Forewing long (length, 850 µm; greatest width, 315 µm) extending almost to tip of the abdomen when directed backward; membrane and margins of both wings bearing setae; venation reduced; with no closed cells; distinct submarginal vein in fore wing meets wing margin at small pterostigma, then continues a short distance as a postmarginal vein; a straight stigmal vein extends down from the margin at roughly 45 degrees for a short distance; uncus absent; Rs vein incomplete; hind wing narrow (length, 500 µm, width, 60 µm); membrane covered with setae and bearing a short straight vein originating from near wing base; hamuli absent; anal lobe replaced by extended setae.

Metasoma: Sessile, with six subequal visible segments and partly exposed terminal 7 segment showing the tip of ovipositor and ovipositor sheaths. What appears to be a coil-like housing of the ovipositor is present.

Comments: Since the transition between the claval and funiclular antennomeres is so slight, it is difficult to determine if the club represents the terminal 6 or 7 segments [ 10]. The horizontal cleft extending across the head between eyes and subocular sclerites is considered a unique feature and could not be found in any other members of the Platygastroidea .

The 15-segmented antennae represent a primitive feature of the fossil and eliminate its placement in any of the previous families of the Platygastroidea [ 5] as well as in all species of the extinct Proterosceliopsidae , except for the Burmese amber Proterosceliopsis plurima Talamas, Shih, and Ren that also has 15 antennomeres [ 6]. The larger body size (3.9 mm versus 1.3 mm in Caradiophyodus saradae gen. and sp. nov.), nine clavomeres (versus 6 or 7 in Caradiophyodus saradae gen. and sp. nov.), extended metasoma, long pedicel, and long sixth tergite also separate the latter species from Caradiophyodus saradae gen. and sp. nov.

Aside from the above, members of the Proterosceliopsidae are characterized by a malarsulcus, a mesepimeral sulcus, a transepisternal line on the mesopleuron, and transverse furrows along the anterior margins of the tergites and sternites [ 2, 6], which are not present on Caradiophyodus saradae gen. and sp. nov.

Caradiophyodus saradae gen. and sp. nov. also differ from the members of the Proterosceliopsidae in the following characteristics. The pronotal cervical sulcus of Caradiophyodus saradae gen. and sp. nov. is not furrowed and associated with glandular excretions as in members of the Proterosceliopsidae [ 6]. In addition, the wing of members of the Proterosceliopsidae has a bulla as well as evidence of a short, nebulous 1Rs vein and a 2Rs (=Rs) vein extending to the wing margin. In addition, members possess a nebulous Rs + M vein, nebulous to weakly sclerotized Mand Cu veins, and a tibia spur formula of 1-2-2 [ 6], which differ from that of Caradiophyodus saradae gen. and sp. nov. The pedicel of the Burmese amber Proterosceliopsis plurima [ 6] is as long as the first three flagellomeres combined, while in Caradiophyodus saradae gen. and sp. nov., the pedicel length is slightly less than the first two flagellomeres. The abdomen is slender and petiolate in P. plurima [ 6] but is broad and sessile in Caradiophyodus saradae gen. and sp. nov. It is clear that the fossil does not belong to the Proterosceliopsidae .

Within the superfamily Platygastroidea , only the Burmese amber Proterosceliopsis plurima [ 6] and Caradiophyodus saradae gen. and sp. nov., possess 15 antennomeres, which is emphasized as a pleisomatic character by Talamas et al. [ 6]. Since Caradiophyodus saradae gen. and sp. nov. cannot be reliably assigned to any known extant or extinct family, it is placed in a new family.

The cleft in the head of Caradiophyodus saradae gen. and sp. nov. is considered a natural feature rather than a post-mortem crack. This is because there is no sign of torn or malformed adjacent head structures. The purpose of such a feature remains unknown.