Bembidion sp.

Luo, Xiao-Zhu, Wipfler, Benjamin, Ribera, Ignacio, Liang, Hong-Bin, Tian, Ming-Yi, Ge, Si-Qin & Beutel, Rolf Georg, 2018, The cephalic morphology of free-living and cave-dwelling species of trechine ground beetles from China (Coleoptera, Carabidae), Organisms Diversity & Evolution (New York, N. Y.) 18 (1), pp. 125-142 : 135-137

Bembidion sp.

External head structures

The head is similar to that of Trechiotes in its general appearance, markedly wedge-shaped in lateral view and moderately long, with the distance of the anterior labral margin to the postocciput slightly longer than the maximum width of the ocular region. Its coloration is blackish-brown. The rather large, compound eyes (ce; Figs. 1d and 2f ) are very distinctly protruding laterally. The clypeus is slightly longer than the labrum. Paired dorsal furrows (ff; Fig. 1d ) are present, and diverging posterior branches almost reach the posterior supraocular ridge (sor; Fig. 1d ). Short and deep longitudinal furrows are present between the anterior tentorial pits and the antennae. The circular line (cirl; Fig. 1d ) on the caudal fourth of the head obliterates towards the posterior tentorial pits, terminating on the caudal third of the head capsule. About one third of the head is retracted into the thorax. The subparallel gula (gu; Fig. 1f ) is about one half as long as the head capsule, and its maximum width is about one fifth of the distance between the outer margins of the eyes.

Sinaphaenops wangorum Trechiotes perroti Bembidion sp.

M. tentorioscapalis O: entire length of anterior tentorial arm, I: + +

anterior (M1) ventrally on basal scapal margin.

M. tentorioscapalis O: upper region of laminatentorium and + +

posterior (M2) basal part of anterior tentorial arm, I: dorsally on basal margin of scapus.

M. tentorioscapalis O: lateral outer wall of laminatentorium, I: + +

medialis (M4) medially on basal scapal margin.

M. scapopedicellaris O: dorsomesal wall of scapus, I: dorsally + +

lateralis (M5) on pedicellar base.

M. scapopedicellaris O: ventromesal wall of scapus, I: ventrally + +

medialis (M6) on pedicellar base.

M. craniomandibularis Largest cephalic muscle, O: with several O: with several bundles along The same attachments internus (M11) bundles along extensive parts of the extensive parts of the lateral as T. perroti . lateral and dorsal surface of the head and dorsal surface of the head capsule; a separate thin tendon that capsule, I: the same as originates from the main tendon at S. wangorum . the constricted area of the head is posteriorly connected to the postoccipital ridge by a relatively small muscle bundle, I: with a strongly developed tendon on the mesal mandibular base.

M. craniomandibularis O: two bundles along large parts of the + +

externus (M12) lateral margin of the head capsule, dorsal bundle almost reaching foramen occipitale, ventral bundle shorter, I: with a tendon laterally on the mandibular base.

M. craniocardinalis O: anteroventral head capsule, directly + +

externus (M15) below ventral bundle of M.12, I: lateral branch of cardinal process with a tendon.

M. tentoriocardinalis (M17) Two subcomponents, O: (a) anterior part + + of the gular wall, near the basal part of the anterior tentorial arms; (b) several bundles along the entire outer surface of the gular ridge, I: mesal cardinal process.

M. tentoriostipialis (M18) Two bundles, O: one with several fibers + + on outer ventral region of laminatentorium, one with several fibers along the entire ventral inner surface of the gular ridge, I: base of stipes.

M. craniolacinialis (M19) O: ventral head capsule, anterior to + + origin of M15, I: together with M 20 with tendon on lacinial base.

M. stipitolacinialis (M20) O: basal margin of stipes, I: together + + with M19 with tendon on lacinial base.

M. stipitogalealis (M21) O: basistipes, directly laterad M20, I: + + basal margin of galea.

M. stipitopalpalis O: base of dorsal plate of palpifer, I: + +

externus (M22) laterally the base of palpomere 1.

M. palpopalpalis O: lateral inner wall of palpomere 2, + +

tertius (M26) I: mesally on the margin of palpomere 3.

M. palpopalpalis O: lateral inner wall palpomere 3, + +

quartus (M27) I: mesally on basal margin palpomere 4.

M. submentopraementalis A single and thin bundle, O: gular + +

(M28) apodeme, I: membrane connecting mentum and prementum.

M. tentoriopraementalis Two bundles, O: one on ventral head Two bundles, O: one on the The same attachments inferior (M29) capsule, laterally in front of the ventral head capsule, posterior as T. perroti .

Figures

Fig. 1 Head habitus of the studied specimens. a–c Dorsal, lateral, and ventral views of S. wangorum. d–f Dorsal, lateral, and ventral views of B sp. g–i Dorsal, lateral, and ventral views of T.perroti. atp anterior tentorial pit, ce compound eye, cfs clypeofrontal suture, cirl circular line, cl

Fig. 2 3D reconstructions of tentoriums (a, b, c) and nervous + digestive systems (d, e, f). a, d S. wangorum. b, e T. perroti. c, f B. sp. Upper part of each image: dorsal view; lower part of each image: ventral view. ata anterior tentorial arm, cer cerebrum, cn connective, dta dorsal tentorial arm, fg frontal ganglion, gur gular ridge, p pharynx, tb tentorial bridge