Timema cf. californicum, S. H. Scudder, 1895

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

Timema cf. californicum

“ California timema (walkingstick)”

Figures 79 , 80 (lateral, anterior, posterior); 81 , 82 (dorsal, anterior, posterior); 83 , 84 (ventral, anterior, posterior)

Plates 49 (lateral), 50 (dorsal), 51 (ventral)

The tracheal morphology of Timema is nota- ble for the proliferation of comparatively thin tracheae that form networks throughout the body. These networks make assessment of homology difficult especially in the thorax, where differentiating similarly networked tracheae from other taxa is unclear. Identifiable homologous tracheae are labeled here, and incorporation of data from some of the 20 or so other Timema species could help to resolve ambiguous structures. Notably, T2,3-DLT are absent in Timema , with the additional absence of the corresponding T2,3-DB; however, the networked nature of tracheae elsewhere likely compensates for the lack of dorsal longitudinal connections. Although distantly related, the Timema thorax is rather reminiscent of termites, with (possibly) dual ventral commissures, which may be convergent.

DESCRIPTION: HEAD: Head tracheae with several networked interconnections dorsoventrally; due to three-dimensional nature of head tracheal architecture, readers are encouraged to refer to models in supplementary digital data. Prominent H-DCT-VCT-Loop at anterior margin of prothorax, with smaller H-DCT and H-VCT branching from dorsal and ventral portions of loop. H-DCT extending anteriad and slightly dorsad, splitting into dorsal branch to H-DX intersection near vertex; and anteriad H-DCT-Ant branch, joining with ventral H-VCT-Ant branch and extending into H-Ant. H-DX with anteriad branches extending laterally and ventrad, reconnecting with H-VCT-Ant as H-DX-VCT-Loop. H-VCT runs anteriad, with H-VCT-Ant branching anterodorsally to join with H-DCT-Ant. H-VCT continues anteriad with H-Mx branching ven- trad; H-Mx with H-VC before branching to H-MxPlp. H-VCT with continued anterodorsal curve, with H-Md branching anteriad; H-VCT joining with H-DCT via H-VCT-Ft-Loop; H-FtLbr branching ventrad near anterior apex of H-VCT-Ft-Loop.

THORAX: T2-S with three branches: H-DCT, H-VCT, and T2-AWL. H-DCT runs directly anteriad toward head; small T1-Cx ventrad in middle of prothorax. H-VCT likewise running anteriad, with T1-AL ventrad at posterior margin of prothorax; T1-PL not present. T1-AL with medial branch to T1-VX. T1-VX branching into three anteriad tracheae, extending toward head as H-VLT, with right side H-VLT fusing with H-VLT-Med anteriad of cervix. T2-AWL runs ventrad and mediad before turning dorsally and posteriad in an S-shaped curve; small T2-DB and T2-VB branching dorsad and ventrally (respectively) from T2-AWL. T2-DB linking with apparent T1-DLT anteriad; T2-DLT not visible. T2-VB runs ventrad at bottom of T2-AWL S-curve, bifurcating into anterior and posterior branches, both leading to network of tracheae forming numerous ventral commissures. Remainder of T2-AWL bifurcating into T2-Wbr and T2-AL; T2-Wbr directly posteriad, linking with T3-S via T2-PWL; T2-AL posteriad and ventrad, linking with T2-PL and extending into midleg. T3 with three branches: T2-PWL, T3-AWL, and T3-VB. T2-PWL runs anteriad, splitting into T2-Wbr dorsally and T2-PL ventrad; T2-PL joining with T2-AL and extending into midleg. T3-AWL runs dorsad, curving posteriorly and splitting into T3-Wbr posteriad and T3-AL ventrad; T3-AL joining with T3-PL and extending into hind leg. T3-VB splitting into four tracheae close to T3-S; at least two of these extending into network of ventral commissures; several X-shaped commissure intersections present.

ABDOMEN: A1..8-S present, short A n -SB spiracular branch present on all A1..8-S. A1-S branching pattern slightly modified from remaining A2..8-S, with T3-PWL running anteriad, splitting into T3-Wbr anteriad and T3-PL ventrad, with T3-PL joining with T3-AL and extending into T3-L. A1..8-MLT present, with A1..5-DB branching dorsad from A n -MLT; A6..8-DB branching directly from A6..8-SB. All A1..6-DB linking with thin, sinuous A1..6-DLT along dorsum; A n -DC not present. A7,8-DLT substantially larger, with fanlike morphology expanding into highly tracheated hind- and midgut “appendices” ( Shelomi et al., 2015). A1..8-VB present, extending to link with sinuous A n -VLT along venter; A2,3,6,7,8-VC present; given distribution, other A n -VC likely present but not visible. Numerous visceral tracheae, most notably forming asymmetric connectives A4-A5-Vi-AsymC and A5-A6-Vi-AsymC; A7-Vi-VC also present.

Figures

FIGURE 79. Timema cf. californicum (Phasmatodea: Timematidae) anterolateral view.

FIGURE 80. Timema cf. californicum (Phasmatodea: Timematidae) posterolateral view.

FIGURE 81. Timema cf. californicum (Phasmatodea: Timematidae) anterodorsal view.

FIGURE 82. Timema cf. californicum (Phasmatodea: Timematidae) posterodorsal view.

FIGURE 83. Timema cf. californicum (Phasmatodea: Timematidae) anteroventral view.

FIGURE 84. Timema cf. californicum (Phasmatodea: Timematidae) posteroventral view.