PHILIPPIDORIPPINAE, Guinot, 2023

Guinot, Danièle, 2023, A new subfamily classification of the highly diversified Dorippidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Dorippoidea), using morphological, molecular and palaeotonlogical data, with special emphasis on its unique female reproductive system, Zoosystema 45 (9), pp. 225-372 : 285-288

Subfamily PHILIPPIDORIPPINAE n. subfam.

TYPE GENUS. — Philippidorippe Chen, 1986 (type species by original designation: P. philippinensis Chen, 1986 ( Chen 1986a: 183, fig. 3a-g, pl. 1, fig 3, pl. 2, fig. 4). Genus monotypic.

DESCRIPTION

Carapace ( Fig. 27A, B )

Carapace wider than long, greatly enlarged and swollen at level of branchial regions. Dorsal surface slightly inflated, finely granular, especially on prominences, without spines. Regions well defined, especially proto-, meso- and urogastric regions. Precervical groove distinct but irregular; cervical groove deep. Branchial lobes low, convex. Gastric pits as two slits just at limit between meso-metagastric and urogastric regions (thus not on cervical groove as indicated by Holthuis & Manning 1990: 132). Front with two pointed submedian teeth separated by narrow, V-shaped median emargination, exposing exhalant channels. Posterior margin of orbit with fissure. Outer orbital tooth triangular, slender, acute, very long and overreaching frontal teeth. Lower orbital margin unarmed, deeply depressed. Inner suborbital tooth large, sharp, not overreaching outer suborbital tooth. Carapace posterior rim thin, rather narrow, not extending sideways along posterolateral margins and lined by weakly developed strip, only thickened laterally, especially in females.

Illustrations: Philippidorippe philippinensis: Chen 1986a : pl. 1, fig. 3, pl. 2, fig. 4; Holthuis & Manning 1990: fig. 57a (reproduced by Sin et al. 2009: fig. 3H); Chen & Xu 1991: fig. 8.1; Chen & Sun 2002: fig. 99.1, pl. 2, fig. 2; Takeda & Manuel-Santos 2006: 96, fig. 6A; Ng et al. 2008: fig. 45.

Cephalic structures ( Figs 27A, B ; 28A, B )

Eyes short and stout, cornea ventrolateral. Antennule obliquely folded and may be completely retracted into fossa; articles short. Antenna entirely directed forward, all along fringed with dense setae: articles 2+3 quadrangular; article 4 short; article 5 slitghly longer; flagellum long.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig. 3a (reproduced by Holthuis & Manning 1990: fig. 58a); Holthuis & Manning 1990: fig. 57b; Chen & Xu 1991: fig. 8.1; Chen & Sun 2002: fig. 99.1.

Oxystomatous disposition ( Fig. 28 A-C)

Opening of exhalant channels visible in dorsal view between rostral teeth. Mxp3 narrow (especially merus) and long, reaching level of eyes.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig. 3a (reproduced by Holthuis & Manning 1990: fig. 58a); Chen & Xu 1991: fig. 8.1; Holthuis & Manning 1990: fig. 57c; Chen & Sun 2002: fig. 99.1.

Pereiopods ( Figs 27A, B ; 28A, B, E )

Chelipeds of females and young males equal in size and shape; marked heterochely in adult males, with smooth outer surface of palm inflated; dorsal margin and outer surface covered with granules and fringed with short hairs.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig. 3b (reproduced by Holthuis & Manning 1990: fig. 58b, c), pl. 1, fig. 3, pl. 2, fig. 4; Chen & Xu 1991: fig. 8.2; Chen & Sun 2002: fig. 99.2, 3.

P2, P3 of males extra-long, P2 longest, slender; meri very long, longer on P2, flattened, with distal spine basally erect; dactyli without fringes of hair. P2, P3 shorter and proportionally stouter in females. P4, P5 very slender; P5 with very long ischio-merus; both ischio-merus and merus of P5 clearly curved, applying on convex sides of carapace.

Illustrations: Philippidorippe philippinensis: Chen 1986a : pl. 1, fig. 3, pl. 2, fig. 4; Holthuis & Manning 1990: fig. 57e.

Thoracic sternum ( Figs. 27C, D ; 28 )

Thoracic sternum wide, granular, tomentose. Sternites 1 and 2 forming a regular triangle (instead of pentagonal shield); very small portion of sternite 1 visible dorsally; sternite 2 separated from sternite 3 by depression; suture 3/4 short, not ending in boutonniere. Sutures 4/5-7/8 interrupted; median longitudinal furrow at level of sternite 4; suture 5/6 moderately curved backwards. Sternal extensions between P2/ P3, P3/P4, shorter betwen P4/P5. Female thoracic sternum only obliquely tilted backwards from middle of sternite 6 ( Fig. 27C, D ).

Illustrations: Philippidorippe philippinensis: Holthuis & Manning 1990 : fig. 57f.

Pleon and telson ( Figs 27 ; 28 )

Male pleon short, not completely filling sterno-pleonal cavity; all somites free, without strong tubercles or spines, only with granules on some somites. Somites 1-3 exposed dorsally; somite 1 rather broad and short, widening slightly posteriorly, posterior margin excavated in middle; somite 2 widening posteriorly; somite 3 with distinctly swollen lateral parts highly visible in dorsal view; somites 4-6 regularly narrowing; telson short, bluntly triangular, slightly exceeding suture 5/6.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig. 3c (reproduced by Holthuis & Manning 1990: fig. 58d); Holthuis & Manning 1990: fig. 57d; Chen & Xu 1991: fig. 8.3; Chen & Sun 2002: fig. 99.4.

Female pleon very wide, with tomentose, granular surface. In adult females somites 1-3 and part of 4 exposed dorsally ( Fig. 27 B-D) (see below, Additional female pleonal-retention mechanism).

Pleonal-locking mechanism by press-button

( Figs 27C, D ; 28D, E )

Press-button located on moderately curved backwards suture 5/6.

Additional female pleonal-retention mechanism ( Fig. 27B )

In females, strong retention by wide, quadrate process of sternite 8 overhanging pleonal somite 2; small telson engaged between slightly raised slopes of sterno-pleonal cavity at level of sternite 5.

Male gonopore and penis

Coxo sternal condition. Sternites 7 and 8 expanded over penis for quite long distance, close together but not completely joined, thus a condition similar to that of Dorippe quadridens , but penial bulb shorter, poorly demarcated from thick, long, sclerotised subsequent portion that is exposed between sternites 7 and 8.

Illustrations: Philippidorippe philippinensis: Guinot et al. 2013: 102 , fig. 17D.

Gonopods ( Figs 28D, E ; 31H )

G1 short, extremely stout, tapering distally; basal half very thick and broad, with rounded basal lobe at outer margin; distal third curved outwards, tip with two auricular processes.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig. 3d, e (reproduced by Holthuis & Manning 1990: fig. 58eh; by Sin et al. 2009: fig. 4H); Chen & Xu 1991: fig. 8.4; Chen & Sun 2002: fig. 99.5, 6.

G2 straight.

Illustrations: Philippidorippe philippinensis: Chen 1986a : fig 3f, g.

Vulvae ( Figs 27D ; 32H )

Vulva rather distant from distal part of sternal ridge, not located on sternal prominence but situated on obliquely directed flank of flared sterno-pleonal cavity; opening not recessed, quite large, elongated, crescent-shaped.

Illustrations: Philippidorippe philippinensis: Holthuis & Manning 1990 : fig. 57f, g; Vehof 2020: fig. 8A.

Female reproductive system

Studied in Philippidorippe philippinensis by Vehof (2020: 51, 57, 70, 73, 86, figs 4, 8, 17, tables 2, 5), unfortunately on a specimen in a very poor state of preservation so that the histological results are fragmentary. See Figure 37 and below, The female reproductive system in Brachyura , its evolution and unique disposition in Dorippidae .

DISTRIBUTION AND HABITAT

Known only from localities in and around the Philippine Islands and from South China Sea ( Chen & Sun 2002). Found at depths betwen 96-107 m and 193-200 m, Philippidorippe philippinensis is the only deep-sea dorippid species ( Chen 1986a; Holthuis & Manning 1990; Chen & Xu 1991; Chen & Sun 2002; Takeda & Manuel-Santos 2006: 96).

CARRYING BEHAVIOUR

Unknown.

REMARKS

The genus Philippidorippe is a deep-water genus and the only dorippid in this case. In a combined analysis using three genes, it has been interpreted as basal in the clade Dorippe - Dorippoides - Medorippe ( Sin et al. 2009) .

Figures

FIG. 27. — Philippidorippinae n. subfam. Philippidorippe philippinensis Chen, 1986, Philippines, Bohol Province, ZRC 2016.0240: A, ♂ 23.0 × 29.3 mm: habitus; B-D, ovigerous ♀ 25.2 × 33.2 mm; B, habitus; C, thoracic sternum with pleon, press-button; D, vulvae.

FIG. 28. — Philippidorippinae n. subfam.Philippidorippe philippinensis Chen,1986:A-D, ♂ 23.0 × 29.3 mm, Philippines,Bohol Province, ZRC 2016.0240:A, ventral view; B, anterior region; C, thoracic sternum with pleon; D, thoracic sternum, G1. E, ♂ 25.0 × 30.0 mm, Philippines, MUSORSTOM 3, MNHN-IU-2018-5201 (= MNHN-B18913): thoracic sternum, G1 and G2.

FIG. 31. — Diversity of G1s in the seven dorippid subfamilies (schematic drawings): A, Dorippinae n. stat. (Dorippe quadridens); B, Dorippoidinae n. subfam. (Dorippoides facchino); C, Medorippinae n. subfam.(Medorippe lanata); D-F, Heikeopsinae n.subfam.:D, Heikeopsis?japonica; E, Neodorippe callida; F, Nobilum histrio; G, Paradorippinae n. subfam. (Paradorippe cathayana); H, Philippidorippinae n. subfam. (Philippidorippe philippinensis); I, Phyllodorippinae n. subfam. (Phyllodorippe armata). (A-H, after Holthuis & Manning 1990; I, after Manning & Holthuis 1981). From Sin et al. (2009: fig. 4). Setae not always figured.

FIG. 32. — Diversity of vulvae in the seven dorippid subfamilies (schematic drawings): A, Dorippinae n. stat. (Dorippe quadridens); B, Dorippoidinae n. subfam. (Dorippoides facchino); C, Medorippinae n.subfam.(Medorippe lanata); D-F, Heikeopsinae n. subfam.;D, Heikeopsis?japonica; E, Neodorippe callida; F, Nobilum histrio; G, Paradorippinae n. subfam. (Paradorippe cathayana); H, Philippidorippinae n. subfam. (Philippidorippe philippinensis); I, Phyllodorippinae n. subfam. (Phyllodorippe armata, ♀ 13.0 × 19.0 mm, Guinean Trawling Survey, MNHN-IU-2021-8731 [= MNHN-B24199]). Setae represented only on B. A-H, modified from Holthuis & Manning (1990).

FIG. 37. — Schematic representation of character mapping of sperm storage organs in the different dorippid subfamilies recognised here (except Phyllodorippinae n.subfam.not studied) and in a typical eubrachyuran:ovary with oocytes; oviduct; cuticular bursae (thin black line), of equal or unequal size; seminal receptacle either bilateral twin- or bilateral single,and either completely cuticular (thin black line) or partially glandular (thick black line). The twin system occurs in Dorippinae n. stat., Dorippoidinae n. subfam., Paradorippinae n. subfam. and Philippidorippinae n. subfam.; the single system occurs in Heikeopsinae n. subfam.,Medorippinae n. subfam.and in the typical Eubrachyura (most, see e.g. Ethusidae). Modified from Vehof 2020: figs 20-22).