Cretomomophron mutilum Rosova, Prokop & Beutel, 2023

Rosova, Katerina, Prokop, Jakub, Hammel, Joerg U. & Beutel, Rolf G., 2023, The earliest evidence of Omophroninae (Coleoptera: Carabidae) from mid-Cretaceous Kachin amber and the description of a larva of a new genus, Arthropod Systematics & amp; Phylogeny 81, pp. 689-704 : 689

publication ID	https://dx.doi.org/10.3897/asp.81.e101374
publication LSID	lsid:zoobank.org:pub:944B0964-DA56-4F9B-926A-940B392C5AC7
persistent identifier	https://treatment.plazi.org/id/53D8F3BA-7280-4FBF-B5E4-BF2ECCD97461
taxon LSID	lsid:zoobank.org:act:53D8F3BA-7280-4FBF-B5E4-BF2ECCD97461
treatment provided by	Arthropod Systematics & Phylogeny by Pensoft
scientific name	Cretomomophron mutilum Rosova, Prokop & Beutel
status	sp. nov.

Treatment

† Cretomomophron mutilum Rosova, Prokop & Beutel sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Material.

Holotype no. PřFUK 46, third(?) instar larva preserved in transparent yellow piece of amber (10.9 × 11.2 × 3.2 mm), deposited in the collection of Department of Zoology collection, Faculty of Science , Charles University in Prague. The specimen embedded in a piece of amber is almost completely intact, but some damage is visible on the anterior head region (e.g., apical tooth of left mandible missing). Parts of the dorsal and lateral surface are covered with bubbles.

Age and occurrence.

Mid-Cretaceous (late Albian-early Cenomanian, 99 million years ago) amber; age based on U-Pb dating of zircon crystals from the volcaniclastic matrix ( Shi et al. 2012).

Locality and horizon.

Hukawng Valley, Kachin State in northern Myanmar.

Measurements.

Length of the inclusion from the tip of the right antenna to the tip of right urogomphus 7.2 mm.

Etymology.

The specific epithet refers to the damaged (mutilated) mandibles.

Description.

Habitus (Figs 1B View Figure 1 , 3 View Figure 3 , 4 View Figure 4 ): Campodeiform larva, with a wedge-shaped head, a large prothorax hexagonal in dorsal view, strongly developed legs with a distinct armature of spines, and a relatively slender abdomen tapering posteriorly.

Coloration.

Sclerotized areas such as thoracic tergites, coxae or parts of the head middle brown to dark brown. Other parts with some degree of sclerotization like legs and abdominal tergites light brown. Membranous or semimembranous regions, e.g., pleural areas, cream-colored.

Setation.

Body surface with a well-developed vestiture of long setae, especially inserted on the dorsal side of the head, on the tergites, and on the pleural areas of the abdominal segments, and urogomphi. Legs with pattern of long chaetae and long, rather thin spike-like setae. Head: Distinctly prognathous, wedge-shaped or shovel-shaped in lateral view, anteriorly strongly flattened (Fig. 3B View Figure 3 ). Strongly sclerotized and dark brown, almost black on dorsal side (Fig. 1B View Figure 1 ). Ventral side less strongly pigmented, brownish (Fig. 2A View Figure 2 ). Dorsally with a set of long setae (Figs 1A, B View Figure 1 ). Coronal suture about 1/3 as long as head capsule and distinct, but frontal sutures only partly visible (obscured by small bubbles) (Fig. 5A View Figure 5 ). Nasale large and roughly triangular, with small, rounded protuberances (Fig. 1A View Figure 1 ; not clearly recognizable in µ-CT data set). Four large stemmata recognizable in dorsal view behind antennae (ventral stemmata not visible; Figs 1A View Figure 1 , 5A View Figure 5 ). Antennae: Four-segmented (Figs 1A View Figure 1 , 5A View Figure 5 ), held upward (Fig. 3B View Figure 3 ); 1st antennomere markedly shorter than others; 2nd antennomere distinctly longer than in Omophron ; apical 4th antennomere narrower than proximal segments, cylindrical, about half as long as 3rd antennomere, and distinctly turned outwards, with three apical setae (broken off) (Figs 2A View Figure 2 , 5A, B View Figure 5 ). Mandibles (Figs 1A View Figure 1 , 2A View Figure 2 , 5A, B View Figure 5 ): Incomplete (apparently damaged, apical tooth broken off), curved inwards, with retinaculum well-developed and bidentate; penicillum not visible, probably absent. Maxillae (Figs 2A View Figure 2 , 5B View Figure 5 ): Maxillary cardo transverse, undivided; stipes elongate, almost twice as long as wide, slightly narrowing distally; with at least two long setae; palpifer not recognizable as a separate element; palp very likely four-segmented but only three palpomeres preserved; 1st palpomere about half as wide as distal edge of stipes, slightly longer than broad; 2nd palpomere cylindrical, elongate, narrower than 1st but more than twice as long; 3rd palpomere slightly narrower than 2nd and shorter than 1st; apical palpomere apparently broken off. Galea two-segmented; proximal galeomere slender, elongate and slightly curved; distal galeomere narrower and less than half as long, apically rounded; lacinia elongate, spine-like, straight or nearly straight, slightly longer than basal galeomere. Labium (Figs 2A View Figure 2 , 5B View Figure 5 ): Labial submentum fully integrated into ventral wall of head capsule, medially divided by ventral ecdysial line; mentum short, trapezoid, membranous; prementum small, roughly quadrangular; distinctly protracted but covered by distal part of enlarged nasale in dorsal view; ligula not clearly visible, possible much shorter than in Omophron ; palps two-segmented; elongate 1st palpomere nearly twice as long as prementum and very slightly curved, slightly narrowing distally; 2nd palpomere distinctly shorter, cylindrical, apically rounded. Thorax: Slightly more than 1/3 of total body length (excl. urogomphi) (Figs 1B View Figure 1 , 4 View Figure 4 ). In lateral view appearing moderately compressed dorsoventrally (Fig. 3B View Figure 3 ). Segments distinctly larger and broader than those of abdomen. Prothorax about half as long as all three segments combined; anteriorly with distinct collar with densely set longitudinal riffles. Pronotum well-sclerotized, with dark brown tergal halves separated by distinct median ecdysial suture; distinctly widening posteriorly, almost twice as wide posteriorly than at anterior edge; lateral edges straight, evenly diverging posteriorly; posterolateral corners not clearly visible. Meso- and metathorax similar except for longer hind legs. Mesonotum slightly wider than metanotum and more distinctly rounded laterally; both sclerotized and divided by median ecdysial suture; both distinctly concave anteriorly and very slightly convex posteriorly. Legs (Figs 2B, C View Figure 2 ): Six-segmented, strongly developed, robust, almost as long as the thorax (Fig. 3B View Figure 3 ). With long chaetae and rather thin spike-like setae, mainly concentrated on distal femur. Hind legs slightly longer than two other pairs. Coxa elongated-conical, almost as long as the pronotum (Fig. 3B View Figure 3 ). Trochanter unusually large, especially on foreleg, with distinct lateral projection on distal apical region (Fig. 2C View Figure 2 ). Femur slightly shorter than trochanter, also distally widened, Tibia cylindrical, about half as long as femur. Tarsus slender, elongated, narrowing towards apex, with apical setae about three times longer than thin paired claws (Fig. 2D View Figure 2 ). Abdomen: Composed of ten segments and narrower than thorax (Figs 1B View Figure 1 , 4 View Figure 4 ). Lateral appendages like gills absent. Segments I-IX with distinctly developed tergites with long setae. Segments III-VI with many setae arranged in transverse rows, in contrast to Omophron where such a pattern is found on segments I-V (K. Makarov, pers. comm.) (Figs 1C View Figure 1 , 4 View Figure 4 , 5C View Figure 5 ). Epipleurites present, forming conspicuous lateral projections with long setae on segments I-VIII (Figs 1C View Figure 1 , 5C View Figure 5 ). Segment IX distinctly narrower than VIII and slightly shorter. Fixed urogomphi present on tergite IX, unsegmented, 0.95 mm long, slightly curved inwards, each with at least eight long outer setae and three shorter inner setae (Figs 1B View Figure 1 , 4 View Figure 4 ). Slender, tube-shaped pygopod formed by segment X, shorter than urogomphi (Fig. 3B View Figure 3 ), covered with short setae.