Fragosublatta pectinata Chen, Shih & Ren, 2021

Chen, Guanyu, Xiao, Lifang, Liang, Junhui, Shih, Chungkun & Ren, Dong, 2021, A new cockroach (Blattodea, Corydiidae) with pectinate antennae from mid-Cretaceous Burmese amber, ZooKeys 1060, pp. 155-169 : 155

Fragosublatta pectinata Chen, Shih & Ren sp. nov.

Figs 1 , 2 , 3 , 4

Type material.

Holotype: CNU-BLA-MA2015001, a male specimen. The specimen was preserved in amber at an angle. Most of the insect body parts are preserved, but major parts of the head and all left tibiae and tarsi are missing. The pronotum and the left forewing are fractured.

Locality and horizon.

Hukawng Valley, Kachin State, northern Myanmar; lowermost Cenomanian, mid-Cretaceous.

Diagnosis.

As for the genus due to monotype.

Description.

Medium-sized brown cockroach, body narrow and flattened, overall body length 8.21 mm/width 2.97 mm (Fig. 1A, B ). Major parts of head not preserved. Eyes and labial palps invisible. Mandibles with two sharp teeth preserved (Fig. 3A ). Only four maxillary palps preserved (total length 1.02 mm), with terminal palpomere oval in shape. Sensilla on palps dense and small, <0.01 mm wide. Both antennae detached from head and missing some antennomeres (Fig. 2A, B ); antennae with 19 and 40 antennomeres respectively; length of antennae slightly shorter than forewing length; both antennae with comb-like extensions at end of each flagellomere. Basal flagellomeres simple, thick and short, medial 20 successive flagellomeres pectinate and apical 13 flagellomeres simple (Fig. 3 ). Longest comb-like extension of pectinate flagellomeres 0.19 mm. Antennomeres roundish to cylindrical with widest base of 0.13 mm. Pronotum (length 2.15 mm/width 1.84 mm, as preserved) with dense tubercles, nearly vaulted (Fig. 1C ), partly sclerotized and melanized, anterior margin covered with obvious hairs. Scutellum distinct, long and wide (ca 0.75/ca1.18 mm).

Forewing obovate, overlapping each other and completely covering abdomen. Left forewing overlapping right forewing. Right forewing 7.7 mm long, anterior margin arched, apex rounded (Fig. 2C ). Right forewing costa 2.13 mm long. Sc field narrow, slightly curved, dichotomized with two veins not meeting margin, occupying about one third of forewing length. R regularly branched. M with only two branches. CuA almost straight, posterior-most veins comb-like, up to nine veins preserved. CuP sharply curved. Most of clavus area sclerotized, anal area obviously smallish, with seven veins. Left forewing 7.37 mm long, damaged basally. R with six visible branches. M with only two branches preserved. CuA richly branched with distinct intercalary veins. CuP simple, probably with only two and relatively straight A veins. Hind wing membranous, transparent. R branched, with 6-7 visible veins, reaching wing margin.

From fore legs to hind legs gradually stronger. Fore coxa short and wide (length 0.76 mm/width 0.37 mm). Femur with carination, 1.15 mm long and 0.28 mm wide, antero-ventral margin of fore femur with even spinules (type C1 according to Roth 2003), terminal spine 0.36 mm long, slightly curved (Fig. 4A ). Tibia (length 0.73 mm/width 0.17 mm) typical in Corydiidae , with long spines, most of spines with serrations (Fig. 4B ). Tarsi five-segmented (length 0.76/0.18/0.14/0.13/0.23 mm), with a total of 1.44 mm long and 0.04 mm wide. Claw symmetrical (Fig. 4A ), strong, 0.18 mm long, arolium absent. Mid coxa with carination, 1.04 mm long and 0.2 mm wide. Trochanter comparatively longer (length 0.39 mm). Femur 1.87 mm long and 0.44 mm wide with two rows of spinules. Terminal spine not curved distinctly, 0.48 mm long (Fig. 4C ). Tibia approximately as long as femur, 1.51 mm long and 0.17 mm wide, with seven spines. Tarsi 2.03 mm long and 0.05 mm wide, first tarsomere longest (length 0.68 mm), terminal tarsomere with symmetrical claws (length 0.13 mm). Hind coxa 1.2 mm long with obvious carination, narrowing from top to bottom. Hind trochanter 0.4 mm long and 0.6 mm wide. Femur strong (length 2.03 mm/width 0.60 mm) with terminal spine 0.29 mm long (Fig. 4C ). Tibia longer (length 3.08 mm/width 0.28 mm) with at least 10 spurs. Tarsi five-segmented (tarsomeres 1-5 lengths 0.82-0.39-0.37-0.36-0.41 mm) but narrow (width 0.07 mm). Plantulae present at four proximal tarsomeres in fore and mid tarsi, which also exist in third and fourth tarsomeres of hind leg. First and second hind tarsomeres apparently have spines, but lack plantulae (Fig. 4A, D, E ). Six sternites visible on abdomen, with sparse chaetae. Cercus moniliform, completely preserved with up to 0.23 mm long sensilla chaetica, divided into eight cercomeres on left (ca 1.51 mm) and nine on right (ca 1.73 mm), basally thicker and apically narrower (Fig. 1D ). Hind margin of subgenital plate convex, setose, with a wide concave incision medially. Styli asymmetrical, left stylus longer (length 0.35 mm) than right stylus (0.16 mm long). Both styli unsegmented.

Etymology.

The name Fragosublatta pectinata is derived from the Latin word of pectinatus referring to the pectinate antennae.

Remarks.

The antennae are detached from the head of Fragosublatta pectinata gen. et sp. nov., but the basal antennomeres of both antennae are close to the head (Fig. 3A ). As shown in Figs 1B and 2B , the length of the left antennae, as preserved, is slightly shorter than the forewing length, which is consistent with the length ratios of the antennae/forewing for many documented fossil cockroaches ( Liang et al. 2019). Therefore, we have high confidence that these two antennae belong to Fragosublatta pectinata gen. et sp. nov. based on these observations. Besides, there are two syninclusions in this amber piece, including a Mycetophiloidea Diptera and a Hemiptera ' Homoptera ' (suspected) close to the hind legs of the new species. Due to poor preservation, we cannot identify the detailed taxonomic classification for these two syninclusions.

Figures

Figure 1. Holotype of Fragosublatta pectinata gen. et sp. nov. CNU-BLA-MA 2015001 A photograph of habitus in dorsal view B photograph of habitus in ventral view C photograph of the pronotum, with arrowhead indicating the tubercles D photograph of the moniliform cercus and asymmetrical stylus. Scale bars: 1.0 mm (A, B), 0.2 mm (C, D).

Figure 2. Holotype of Fragosublatta pectinata gen. et sp. nov. CNU-BLA-MA 2015001 A line drawing in dorsal view B line drawing in ventral view C line drawing of the right forewing, with circles indicating the incomplete veins. Scale bars: 1.0 mm (A, B), 0.5 mm, (C).

Figure 3. Holotype of Fragosublatta pectinata gen. et sp. nov. CNU-BLA-MA 2015001 A photograph of the two antennae, with arrowheads indicating the maxillary palp and the mandible B the apical section of the longer antenna C the medial section of the longer antenna D photograph of the shorter antenna. Scale bars: 0.5 mm (A), 0.1 mm (B, C), 0.25 mm (D).

Figure 4. Holotype of Fragosublatta pectinata gen. et sp. nov. CNU-BLA-MA 2015001 A photograph of the foreleg B details of the foretibia spurs, with arrowheads indicating the serration C photograph of the midleg and hind leg, with arrowheads indicating the terminal spines D photograph of the midtarsus E photograph of the hind tarsus. Scale bars: 0.5 mm (A, C), 0.25 mm (B, D, E).