Araneagryllus dylani, Heads, 2010

Heads, Sam W., 2010, The first fossil spider cricket (Orthoptera: Gryllidae: Phalangopsinae): 20 million years of troglobiomorphosis or exaptation in the dark?, Zoological Journal of the Linnean Society 158 (1), pp. 56-65 : 58

ARANEAGRYLLUS DYLANI SP. NOV. ( FIGS 1–3 )

Etymology: The specific epithet is a noun in the genitive case, and is named in honour of my son, Dylan L. Heads. The gender is masculine.

Type: Holotype female: Dominican Republic, Early Miocene (Burdigalian, 18–20 Mya) Dominican amber; AMNH specimen number DR-12-32. Syninclusions: this piece of amber is particularly rich in biotic inclusions, including an isopod, a thysanuran, a collembolan, an auchenorrhynchan, two chalcidoid wasps, and numerous Diptera. The specimen is notable for the development of a white emulsion, particularly around the abdomen and mouthparts.

Diagnosis: As for the genus (vide supra).

Description: Female: body form robust ( Figs 1 , 2A ); 12.11-mm long, measured from head to abdominal apex (excluding ovipositor). Head hypognathous ( Fig. 2B ); vertex broad, with numerous dark spots extending towards the fastigium, which protrudes between the antennal fossae and is covered with a patch of short setae; frons gently sloping; frontal costa shallow, indistinct; subocular furrow distinct, curved medially towards the frontoclypeal suture; genae almost triangular in shape, covered in minute pits, with two dark spots beneath the compound eyes and a much smaller dark spot towards its ventral margin; compound eyes well developed, globose, situated high on the head, and protuding laterally; ocelli absent; antennal fossae situated directly anterior of the compound eyes; scape large, longer than wide and pedicel markedly smaller, only slightly longer than wide; first, second, and third flagellomeres small, as long as wide; subsequent flagellomeres markedly longer than wide; clypeus, labrum, and other mouthparts largely obscured by white emulsion; mandible apparently strong; maxillary palp long, terminal palpomere markedly inflated apically; labial palp smaller, largely obscured by emulsion. Pronotum shield-like, wider than long, with prominent median and marginal carinae and irregularly spaced short setae; pleural margin with prominent dark band and pale ‘lip’ on anterior pleural lobe; median carina with dark stripe, bordered laterally by several dark spots; anterior and posterior margins of pronotum with prominent rows of long setae. Meso- and metanotae and abdominal tergites broad, decreasing in size posteriorly and of largely uniform dark coloration; posterior margins of abdominal tergites with rows of setae. Abdomen largely obscured by emulsion; cerci incomplete (truncated by surface of amber), broad basally, narrowing apically, with a dense covering of setae; epiproct triangular, covered with emulsion; ovipositor incomplete (truncated by surface of amber), strong basally, narrowing apically; subgenital plate broad basally, narrowing slightly posteriorly, with a small median posterior notch. Pro- and mesothoracic legs long, robust ( Fig. 3A, B ). Procoxa large, broadly articulated with prosternum; protrochanter much smaller, largely obscured by a large bubble; profemur broad basally, narrowing very slightly towards apex, covered in fine setae and numerous irregular dark patches; numerous longer setae on the dorsal surface, particularly distally; genicular lobes prominent, inflected; protibia a little over half the length of profemur, with three dark bands and two apical spurs of equal length; tympana absent; probasitarsus three-quarters as long as protibia, with prominent apical spine; second tarsomere small; third tarsomere long, gracile. Mesocoxa approximately half the size of procoxa; mesotrochanter small, triangular; mesofemur similar to profemur, with irregular dark patches, prominent genicular lobes, but with more numerous long setae; mesotibia a little over half the length of mesofemur, with three dark bands and two apical spurs of equal length; tarsus as in the prothoracic leg. Metathoracic leg long, robust, saltatorial ( Fig. 3C ); metafemur strongly inflated basally, with numerous dark patches along the outer facets and dark bands distally; metatibia equal in length to metafemur, with four dark bands; denticulate with two parallel rows of between ten and 12 short spines and four long subapical spurs; three apical spurs, with the median spur markedly longer; metabasitarsus long, with a single dark band, and one long apical spur; second tarsomere much reduced; third tarsomere long, gracile, slightly curved.

Figures

Figure 1. Araneagryllus dylani gen. et sp. nov., photomicrograph of holotype AMNH DR-12-32. Scale bar: 3 mm.

Figure 2. Araneagryllus dylani gen. et sp. nov., camera lucida drawings of holotype AMNH DR-12-32. A, general habitus of specimen. Scale bar: 3 mm. B, left lateral view of head. Scale bar: 1 mm.

Figure 3. Schematic reconstructions of the legs of Araneagryllus dylani gen. et sp. nov. showing the tibial armature and the distribution of the colour pattern. A, prothoracic leg. B, mesothoracic leg. C, metathoracic leg. Scale bar: 3 mm.