Meconema thalassinum (De Geer, 1773)

Herhold, Hollister W, Davis, Steven R, Degrey, Samuel P & Grimaldi, David A, 2023, COMPARATIVE ANATOMY OF THE INSECT TRACHEAL SYSTEM PART 1: INTRODUCTION, APTERYGOTES, PALEOPTERA, POLYNEOPTERA, Bulletin of the American Museum of Natural History 459 (1), pp. 1-184 : 1-184

Meconema thalassinum

“Drumming katydid”

Figures 67 (lateral), 68 (dorsal, ventral)

Plates 43 (lateral), 44 (dorsal, ventral)

The female drumming katydid we scanned is likely a late-stage instar due to the reduced wings. T 2-DB-Vi and T 3-DB-Vi each form a trapezoidal set of double dorsal commissures. It is possible that these may be homologous with sausagelike dorsal commissures seen in other taxa that might be for weight relief or could be involved in stridulatory sound dissemination.

DESCRIPTION: HEAD: Three pairs of tracheae into head: H-DCT, H-VCT, and H-VLT. Head with several interconnected dorsoventral and lateral loops; readers are encouraged to review the supplementary 3D digital models. Air space, possibly a preservational artifact, present in right side of head capsule (see fig. 69). H-DCT runs anteriad, curving dorsally along head capsule and curving medially to connect in a loop just dorsal of eyes. H-DC present. Anteriad of cervix, H-DCT-Oc branches ventrad, linking with H-VCT-Oc with Y-shaped junction to H-Oc-Md. Several small, visceralike H-Oc run dorsad from H-Oc-Md; H-Oc-Md anteriad, reconnecting to H-VCT with H-Md branching anteriad, with lateral H-FtC branch linking left and right side. H-VCT runs anteriad with ventral curve; T 1- AL running posteriad prior to H-VCT entry to head capsule. H-VCT with aforementioned H-VCT-Oc branch running anteriad; H-VCT continuing anteriad with ventral branch, linking with H-VLT before continuing into H-Mx and H-Lbm split.

THORAX: T 2- S opening very large, positioned under pronotum; T 2- S with five branches: T 2-DB, T 2-VB, H-DCT, H-VCT, and T 1- PL. Several tracheae behind T 1-DVi; see figure 70 for view rotated to see additional detail. Readers are also directed to 3D models from supplemental digital data. T 2-DB and T 2-VB from short dorsal spiracular branch, extending directly dorsad and ventrad, respectively. T 2-DB with T 2- AWL split, with T 2-DB continuing dorsad, connecting with T 2- DLT extending posteriorly. T 2- AWL runs dorsad with sharp curve directly ventrad toward midleg; T 2-W-c-r positioned posteriad at apex of curve. T 2-VB runs directly ventrad from T 2-DB/ T 2-VB split, arcing posteriad to connect with T 2- VLT; several small visceral branches forming cagelike network along venter. H-DCT runs dorsad from T 2- S, arcing anteriad and continuing through prothorax into head capsule; T 1-DVi branches forming cagelike morphology along inner wall of protergum, around H-DCT. H-VCT runs dorsad, arcing ventrad before turning anteriad into head capsule, arranged along outside of enlarged T 1- PL; T 1- AL with ventral branch anteriad of T 1- PL. T 1- PL greatly enlarged in hornlike arc, reducing in size and extending into proleg. T 1-L-Ty tympanum present on foreleg tibia. T 3- S much smaller than T 2- S, with five branches: T 3-DB, T 2- PWL, T 3- AWL, T 3-VB, and T 2- PL. T 3-DB and T 3-VB split dorsad and ventrad after short dorsal spiracular branch from T 3- S. T 3-DB running directly dorsad, with T 3- AWL branching dorsad and slightly lateral; T 3-DB continuing dorsad to join with T 2- DLT from anterior and smaller T 3- DLT posteriad. T 3- AWL runs dorsad, with sharp curve ventrad and posteriad toward midleg. T 3- AWL with two connections to tracheae leading to A 1- S: T 3-Wbr, branching dorsally at apex of curve, with T 3-W-c-r and T 3-W-cu-a dorsad; and apparent T 3- PWL extension, dorsal and anteriad from A 1- S, connecting with T 3- AWL / T 3- AL. (See Discussion on Orthoptera .) T 3-VB runs mediad and ventrad, connecting with T 3- VLT toward posterior and T 2- VLT anteriad. T 2- PL ventrad with curving T 2-pf branch to T 2- VLT; T 2- PL continues into midleg, joining with T 2- AL.

ABDOMEN: A 1..8- S present. A 1- S modified, positioned slightly dorsad relative to A 2..8- S. A 1- S with four connections: A 1-DB, T 3- PWL, A 1-VB, and T 3- PL. Single A 1-DB runs dorsad and slightly anterior, broad and flat; intersecting with T 3- DLT anteriad and A 1- DLT posteriad. Several small visceral-type tracheae connecting with T 3- PWL and and likely extending into flight musculature. T 3- PWL running dorsad and anteriad, similar to A 1-DB but smaller; T 3- PWL splitting slightly dorsad into T 3-Wbr anteriad connection to T 3- S, and smaller unnamed extension connecting to T 3- AL (see THORAX, above, and Discussion section on Orthoptera ). T 3- PL thick, running directly ventrad from A 1- S, connecting with smaller T 3- AL from metathorax and extending into hind leg. T 3-VL present, extending into hind leg from T 3- VLT. A 1-VB runs ventrad and slightly mediad, connecting with T 3- VLT from anterior and A 1- VLT posteriad. A 2..8- S similar, each with anterior and posterior dorsal branches A n -ADB and A n -PDB, both intersecting with A n - DLT along dorsum. A n -VB short, running ventrad and slightly mediad, connecting directly to A n - VLT along venter. X-shaped commissures positioned ventrad to VLT (see fig. 71). Numerous visceral tracheae present in abdomen, often spanning several segments, but none appearing to connect segments longitudinally.