Jurachresmoda gaskelli, Zhang, Xin-Wen, Ren, Dong, Pang, Hong & Shih, Chung-Kun, 2008

Zhang, Xin-Wen, Ren, Dong, Pang, Hong & Shih, Chung-Kun, 2008, A water-skiing chresmodid from the Middle Jurassic in Daohugou, Inner Mongolia, China (Polyneoptera: Orthopterida), Zootaxa 1762, pp. 53-62 : 54-57

Jurachresmoda gaskelli sp. nov. Zhang, Ren and Shih

Etymology. The specific name is dedicated to Mr. Tony Gaskell for being an excellent business leader and role-model, providing guidance, motivation and encouragement to Dr. Shih.

Material. Holotype: Large body with legs, female, part and counterpart, No. CNU-CH-DHG2007010-1 & -2. Paratype: nymph, smaller size, probably male, only part, No. CNU-CH-DHG2007011; nymph, probably male, only part, No. CNU-CH-DHG2007012.

Horizon and locality: Jiulongshan Formation, Middle Jurassic, Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia (Nei Mongol Autonomous Region), China.

Diagnosis. Fore tibia are long, representing approximately 59% of the femur. Other diagnostic characters are the same as those of generic diagnosis.

Description. Based on holotype specimen, female, CNU-CH-DHG2007010-1 & -2.

Size large, wings exceeding the length of the abdomen ( Figs. 1–2 ). Head small, broadly pressed. Antennae filiform, distinctly segmented, with more than 18 segments, are 15.7mm long, shorter than the length of fore femora. Antennae are covered with short hairs ( Fig. 3 ). Mouthpart is covered; some blurry palpi can be distinguished in the counter part. Compound eyes are impossible to discern. Thorax is longer than width, with clear sides and vertices, the sides with smooth margin. The notum is clear, while sterna of thorax are poorly preserved. Prothorax is short, tightly connected with the head. Mesothorax is slightly elongated, gradually broadened, somewhat trapezoidal, longer than prothorax and metathorax. Lengths of prothorax: mesothorax: metathorax is approximately 3.0mm: 5.6mm: 3.3mm. All legs are of the same shape, long and narrow, covered with dense short hairs. Coxae are somewhat robust. Pairs of coxae are widely separated, all similar; those on the same side of thorax are apart from each other. Parts of the legs are not preserved. Mid femora are long (32.5mm), so are the fore femora (28.8mm). Fore tibiae (17.1mm), elongated and extended, represent approximately 59% of the length of femur. Mid tibiae are 25.1mm long. Mid legs are probably the longest. Hairs and setae along the legs are relatively well preserved. Their arrangement is similar to those of other species. In addition to hairs and setae along the legs, some prominent long fringing hairs are on parts of the mid leg tarsi and tibiae ( Fig. 4 ). They can be observed in the left mid leg of CNU-CH-DHG2007010-1 (part); and probably exist in the right. They can also be seen in the counterpart specimen. These hairs are somewhat similar to those on legs of extant water-strider, Gerris (Hemiptera) ( Fig. 4 D). They are probably associated with effective skiing on water surface by the new species. The ultra-articulated tarsi are clearly preserved, and these numerous “segments” exist not only in the tarsi, but also in some parts of tibiae ( Fig. 4 ). Some of them are probably related to fossilization processes, but cannot be identified as the tarsomeres described by Nel et al. (2004, 2005).

Wings, exceeding the length of the abdomen, are longer than 37.2 mm. Due to folding and overlapping, most venations are indiscernible. Few longitudinal veins can be observed faintly, but they seem to remain parallel to the margin. Cross veins are invisible. Abdomen, with eight visible segments, was pressed apart. Ovipositor is long and strong, sword-like. Since covered by wings, it is impossible to distinguish details of the valvulae. Cerci are invisible in the adult but prominent in nymph.

Nymph. CNU-CH-DHG2007012 is poorly preserved; following descriptions are mainly based on paratype specimen of CNU-CH-DHG2007011 ( Fig. 5 ).

Both nymph specimens are found without ovipositor, probably male. Appearing similar to adult, the nymph is smaller in size. Their wing buds are evident. Eight segments of abdomen are visible. Fore tibia (10.9mm), elongated and extended, represents approximately 59% of the length of the fore femur (18.5mm). Mid femora are longest at 22.5mm long, followed by the hind femora (19.7mm). Ultra-articulated tarsi are also found in nymph. Furthermore, some numerous “segments” exist in femora and tibiae, which may be the fossilization artifacts ( Fig. 6 ).

Specially, cerci of nymph are particularly long (5.1mm in CNU-CH-DHG2007011; 6.8mm in CNU-CH- DHG2007012), with at least 5 segments. These long cerci represent more than 30% of the length of the abdomen (15.1mm in CNU-CH-DHG2007011; 18.7mm in CNU-CH-DHG2007012) ( Fig. 7 ). Such long and segmented cerci have never been found in other species of this family. They are unique in Chresmodidae . Remarks. Jurachresmoda gaskelli gen. et sp. nov. can be distinguished from C. obscura by characters that the former has tibiae in different length, with longer fore tibiae compared to the femora.

C. aquatica is quite different from J. gaskelli . The former has shorter antenna (antenna 17 segments, 11mm long in C. aquatica ; but more than 18 segments with length of 15.7mm in J. gaskelli ), and shorter wings (not exceeding the length of the abdomen in C. aquatica , but the wing length exceeding the length of the abdomen in J. gaskelli ,).

C. libanica was erected based on nymphs; different from nymphs of J. gaskelli by its smaller size, shorter fore tibiae and cerci.

C. orientalis was also found in China, but had a much shorter fore tibiae, compared to the fore femora (35%~36% in C. orientalis after Esaki, 1949: p. 1; and 59% in J. gaskelli ).

Saurophthiroides mongolicus is based on a specimen without wings, probably a nymph ( Ponomarenko, 1986; Rasnitsyn, 2002; Nel et al., 2004). The nymph of J. gaskelli differs from it by the larger body size, longer antennae, and segmented cerci.

Sinochresmoda magnicornia can be distinguished from J. gaskelli by characters that the fore tibia is shorter, approximately 40% of the femur length. Wings are short in S. magnicornia , not exceeding the length of the abdomen; but long in J. gaskelli , exceeding the length of the abdomen. In addition, antenna and fringing hairs along the wings are unique in Sinochresmoda .

Besides, J. gaskelli possesses elongated mesothorax, long and segmented cerci in the nymph, all of which are unique among Chresmodidae .

Figures

FIGURE 1. Jurachresmoda gaskelli n. g. n. sp., holotype, female: A. photograph of CNU-CH-DHG 2007010 - 1, part, scale 20 mm; B. photograph of CNU-CH-DHG 2007010 - 2, counterpart, scale 20 mm.

FIGURE 2. J. gaskelli n. g. n. sp., holotype, line drawing of part, scale 20 mm.

FIGURE 4. Photographs of partial tibia and tarsi of mid legs of J. gaskelli n. g. n. sp., Holotype: A. right mid leg of counterpart, scale 5 mm; B. left mid leg of part, scale 5 mm; Arrows indicating locations of segments or “ wrinkles ” on tarsi and tibia. C. line drawings of tarsus and partial tibia, the upper: left mid leg of part; the lower: right mid leg of counterpart; both scales 5 mm. Arrows indicating locations of segments or “ wrinkles ” on tarsi and tibia; D. Aquarius sp. (Hemiptera: Gerridae), extant species, left mid leg; scale 2 mm.

FIGURE 5. Photographs of J. gaskelli n. g. n. sp., Paratypes, male, nymph: A. CNU-CH-DHG 2007011, scale 10 mm; B. CNU-CH-DHG 2007012, scale 10 mm.

FIGURE 6. Photographs of J. gaskelli n. g. n. sp., paratype, nymph, legs of CNU-CH-DHG 2007011: A. right fore leg; B. right mid leg; C. right hind leg, all scales 5 mm. Arrows indicating locations of segments or “ wrinkles ” on femur and tarsi.

FIGURE 3. J. gaskelli n. g. n. sp., holotype, part: A. line drawing of antennae, scale 3 mm; B. short hairs on antenna, scale 1 mm.

FIGURE 7. J. gaskelli n. g. n. sp., Paratype, nymph, CNU-CH-DHG 2007011, line drawing of cerci, scale 2 mm; B. Photographs of cerci, scale 2 mm.