REDESCRIPTIONS OF TWO SPECIES OF SEPIA (CEPHALOPODA: SEPIIDAE) FROM SOUTH AFRICAN WATERS: SEPIA ROBSONI (MASSY, 1927) AND S. FAUREI

Two species of cuttlefish: Sepia robsoni (Massy) and Sepia faurei Roeleveld, are redescribed based on sexually mature males and females of both species. They were previously known only from their holotypes: male and female, respectively. They belong to a distinct group of small-sized sepiids, all nearendemics of southern African waters. The knowledge of the systematics and biology of this group is still limited despite the long time since the first description (1875). This is because, inter alia, of their small size: not larger than 4 cm mantle length at maturity. Twenty-one individuals of S. robsoni described here were scattered from Port Nolloth area to the Tsitsikamma coast (bottom depth <37–449 m). Eight known individuals of S. faurei came from the eastern Agulhas Bank (bottom depth 116–184 m). S. robsoni can be identified by extremely thinly calcified cuttlebone (transparent); smooth skin of dorsal mantle and head; tips of first pair of arms thick, finger-like, devoid of suckers. S. faurei can be distinguished by the following combination of characters: thick, heavily calcified cuttlebone but with flat and fused inner cone; skin of dorsal mantle and head very densely covered by characteristic warts; thin, whip-like tips of first pair of arms devoid of suckers. All described specimens of both species are deposited in the South African Institute of Aquatic Biodiversity (SAIAB) and in Iziko, South African Museum (SAMC). key words: small cuttlefish; redescriptions; South African waters; Sepia; Digitosepia


INTRODUCTION
Previous contributions (Lipiński & LesLie 2018, Lipiński 2020) concerning small-sized Sepiidae from southern Africa have outlined possible directions of research upon systematics of these peculiar cephalopods. In particular, a new subgenus (Digitosepia) was proposed with the following characteristics: sepiids with a substantially modified cuttlebone, combined with tips of I pair of arms devoid of suckers. This work adds thorough descriptions of two species of this subgenus, known before only from their holotypes: Sepia robsoni (Massy, 1927) and Sepia faurei Roeleveld, 1972. The original description of S. robsoni (holotype ML 17 mm, male, maturity stage not mentioned) is brief, but includes most important characters of diagnostic significance. The description (and illustration) of the tips of both arms I, which were devoid of suckers, was most notable. Massy (1927) considered this character as a possible result of an accident and subsequent regeneration. This was impossible to verify until now, as there were no further records of S. robsoni. The same concerns the cuttlebone, as Massy (1927) regarded her specimen as "totally dissolved", therefore she did not illustrate "the membranous part remaining". As pointed out by Lipiński (2020), cuttlebones of small-sized sepiids may provide crucial characters of this group (shared by all eight species known to date). It is therefore important to provide even partial details of their cuttlebone morphology. Massy (1927) provided drawings of the general habitus of the species (dorsal and ventral aspect), club, arm and club suckers, beaks, I pair of arms and radula.
The original description of S. faurei (holotype ML 21 mm, female, maturity stage not mentioned) is fairly thorough, but with obvious limitations. Roeleveld (1972) illustrated the general habitus (dorsal and ventral aspect), tip of arm of I pair, club, and cuttlebone (incomplete). She also provided a comparison of characters between S. robsoni, S. dubia and S. faurei (in a separate table).
The aim of this paper (as the two preceding papers) was two-fold. One was to give detailed morphological descriptions or redescriptions of small cuttlefish, as their systematic status required. The second was to provide as much illustration of intra-specific variation in each species as possible, to facilitate identification in the field. Therefore, many illustrations are provided.

MATERIAL AND METHODS
Methods of this study were already outlined by Lipiński & LesLie (2018) and Lipiński (2020). Some details are repeated here for clarity. Specimens for this study were collected using bottom trawls during demersal research surveys off the west and south coasts of South Africa by the research vessels RS Africana, R/V Dr Fridtjof Nansen, and some commercial trawlers (Fig. 1). Details of bottom trawl gear, trawling, sorting and processing of the catch, and references thereof were given in axeLsen & Johnsen (2014), although it should be noted that they erroneously recorded the codend mesh size of the gear deployed by the RS Africana; the correct mesh sizes are 112 mm codend with 35 mm small mesh lining.
Measurements and counts (see Table 1 for definitions) follow roeLeveLd (1972), roeLeveLd & LiLtved (1985, and Lu & reid (1997) and were taken from preserved specimens. The following changes to the terms and definitions given in Lipiński & LesLie (2018: table 1) are made here. 1. There is a vague difference between CIRC (definition: Table 1) and TrRC (Transverse Row Count; Lu & reid 1997: 279); therefore, TrRC is re-named LORC and defined as the number of suckers counted at midline along the length (Tcl) of the club. 2. CES was imprecisely defined and not easy to follow; it is defined here as the total number of suckers along the border of the whole club (combined total count from both sides of the club). 3. Maximum width of cuttlebone (WL; used in many studies) is added to the measurements of small sepiids, defined as the greatest width of cuttlebone (perpendicular to L). 4. TIP1AL is defined as the length of the suckerless tip of I pair of arms. Dorsal (ML) and ventral (MLv) mantle length were measured to the nearest mm below using slide callipers. Fin length (FL) was measured by placing a thread along the base of the fin from the anterior edge and marking the position of the posterior end of the fin, the length of the thread was then measured on a metal ruler. All other measurements were taken using dividers or a graticule in a stereo dissecting microscope at 10× magnification. Sucker diameters were measured at 40× magnification. Measurements    Roeleveld, 1972. 3. Papillae are prominent, complex protuberances in the following forms: -Turrets (see roeLeveLd & LiLtved 1985) where tubercles and/or warts are on top of each other; sometimes they form elaborate structures. -Clusters where tubercles and/or warts are next to each other, forming a distinct unit. -Patches where various structures (some or all defined above) are combined in one distinct unit (for example by elevated tissue). The term turret-cluster was proposed and defined earlier (Lipiński & LesLie 2018). However, the use of this term was found impractical in the reality of small sepiids. With the varied state of preservation of the material, and the large natural variation the term was difficult to recognise as such. Please note that the term "patch" was already used by Roeleveld (1972: 254, 265). Cuttlebone descriptions use standard terms (e.g. Roeleveld 1972), except striae and septa. The use of "septa" is restricted here to the phragmocone and means not only walls between the chambers (there are hardly any chambers in small sepiids), but also layers of relatively thicker calcification within the phragmocone, which mark growth increments. "Striae" are used more loosely, mainly indicating growth lines of the dorsal shield. The relation of these marks to time is unknown and was not researched. The usage of the term "calcification" (used rather inconsistently in the sepiid literature) is explained in the Discussion.
Most of the photographs were taken using Canon EOS 7D Mk I camera and Canon EOS 650 camera coupled with Nikon stereomicroscope using a specially engineered ring.
Abbreviations for museums holding the material are: SAIAB -South African Institute of Aquatic Biodiversity, Grahamstown South Africa; SAMC -Iziko, South African Museum in Cape Town, South Africa; BMNH -specimens at NHMUK catalogued prior to 1992; NHMUK -Natural History Museum London, UK.    (Table 2). Mantle squat, globose, oval (rounder in smaller animals), dorso-anterior margin more often than not wide Ʌ-shape (Figs 2-5), but may be also straight (Figs 6-9). Ventro-anterior margin either straight (Fig. 11) Table 2), relatively short, strong membrane joining pairs I-IV proximally for about 30-50% of arm length, absent ventrally between arms IV (Figs 19,22) in both sexes. Protective membranes well developed, fleshy, but also variable, tend to be more prominent in large females (Figs 19-22). Suckers globular, bi-serial on all arms; sucker rows closely spaced in males, they may be wider apart in females . Diameters of suckers variable (Table 2); they change rather abruptly along arms III-IV in females (after 6-10th pair of suckers and again after 2-4th pair of suckers). Sucker rings on arms smooth, and on club with tiny teeth (Fig. 24). Tips of arms of I pair devoid of suckers, thick, fleshy, finger-like, with narrow cleft in oral mid-line; sometimes knobby in appearance. Tips may be of different length on each arm (range 29-40% of length on I pair arm) . Tips of arms IV in the large female (SAIAB 209578) also devoid of suckers (Fig. 23) of occurrence of this character has to be assessed on a larger material than currently available. Arms and especially their armature modified in mature males, suckers enlarged on arms I-IV except 2-4 terminal sucker pairs (Figs 19-21). Left ventral arm IV hectocotylised ( Fig. 28): single basal sucker large, subsequent pairs become gradually smaller (on ventral margin much smaller); there are 11 pairs of marginal suckers, each marginal line straight; then five pairs of enlarged suckers (last much smaller than the others of the five pairs; Fig. 29) and one small distal sucker. Hectocotylus tip with tiny bi-serial small suckers (Fig. 29) starts the fold; ventral sucker starts the next fold and so on) (Fig. 28). Right ventral arm also modified (Fig. 30), sucker arrangement from base to tip: single very large sucker, then eight pairs of greatly enlarged bi-serial suckers; seven pairs of much smaller suckers, gradually becoming smaller; 7-8 pairs of tiny bi-serial suckers to tip. Tentacular stalk moderately long (85-150% ML), club large (15-25% ML) (Figs 31-32) with sub-equal small suckers in 12-16 transverse rows of 3-4 suckers each. Protective membranes narrow, well separated. Natatory membrane well developed, continuing along tentacular stalk for about one club length. Club axis is a continuation of tentacular stalk (Figs 31-32).

SYSTEMATIC ACCOUNTS
Beaks small, fragile, of typical sepiid proportions. Upper beak (Figs 33-34): rostrum blunt, relatively short, slightly hooked, somewhat longer than wide, rostrum angle strongly curved; hood high above crest posteriorly; jaw edge straight, jaw angle <90°; posterior edge of lateral wall curved; only rostrum and hood dark. Lower beak (Figs 35-37): rostrum short, blunt, jaw angle rounded, broad, <90°, cutting edge straight; hood low on crest; crest curved; crest and lower edge of lateral wall not parallel; shallow fold on lateral wall; posterior edge of lateral wall oblique and rounded; only rostrum, anterior part of hood and anterior part of shoulders dark. Radula (Fig. 24) simple, homodont, with seven teeth in single row: sharp, pointed, forming high triangle indented at base. Lateral teeth slightly smaller than rhachidian teeth, relatively straight. Marginal teeth long, straight, blunt. Spermatophores (Fig. 24) seem to bear no species-specific characters, but they are illustrated for the record (for more detailed comparative research in the future).
Funnel with valve (Fig. 41). Funnel organ well defined: dorsal part with weak anterior ridge and papilla; arms relatively short, thick and fleshy; ventral part simple, elongated oval (Fig. 41).
Cuttlebone extremely lightly calcified, thin and fragile (Figs 42-47 be dissolved completely in even slightly acid preservative, leaving only faint marks - Fig. 45). Septa thick, straight in middle, convex at margins, first (anterior) one not thickened, with dot calcification (Fig. 47), far from anterior border. Striae strongly convex. Dorsally, along mid-line, elevated strip which broadens anteriorly, forms low but distinct ridge. Growth layers of dorsal shield visible. At base (anteriorly), inner cone is thin and flat, completely fused with phragmocone and dorsal shield. Forked limbs absent, completely reduced. What appears as small "tubercles" marginally and anteriorly, are signs of dot calcification. Outer cone broad, transparent. Posterior cone transparent, ends in distinct yellow knob (no spine). No sexual dimorphism was observed in cuttlebone characters.

Remarks.
In the small size range investigated this small-sized species is sexually mature at 22 mm ML (both sexes). Juveniles have not been recorded. Massy (1927) stated that among the "grooved" arm suckers "none is enlarged in the male". However, since she examined no females, this statement is not correct (compare Figs 19-22). Considering natural variation, I found no other discrepancies between Massy's description and the present one. I have provided a photograph of the holotype (Appendix: Fig.  A1) for comparisons and future reference.
Sepia robsoni differs from all other small sepiids (described so far) in the following characters: absence of ventral pores (present in S. typica); tips of I pair of arms devoid of suckers, which is easily seen despite the small size of the species (normal suckers to the end in S. pulchra Roeleveld et Liltved, 1985 faurei Roeleveld, 1972). There are no dense warts nor large tubercles on the dorsal head (present in S. roeleveldi Lipiński, 2020). Each of these species seems to differ rather profoundly from all others in the cuttlebone characters, although cuttlebones of small-sized sepiids themselves, as a group, may have distinct characters in common. However, this needs to be further examined, described and illustrated by a separate, comparative study. Cuttlebones of all small-sized sepiids are very difficult to dissect without damage because of their great fragility (Lipiński 2020). Distribution. S. robsoni, probably near endemic to South Africa, is known both from western and southern waters of South Africa (Fig. 1). The known depth range is <37-449 m (specimens obtained by bottom trawls), therefore their habitat is probably diverse. Roeleveld, 1972 (Figs 48-87, (Figs 52-55). Fins robust and wide, ending rather close to anterior mantle margin (FIa 11-17% ML; Figs 53, 56, Table 3); small gap posteriorly between fins. Colour of dorsal mantle, head and arms in preserved (10% formalin followed by 70% ethyl alcohol) specimens variable: either reddish brown, dark brown or almost purple (Figs 48-51). Dorsal mantle, head and arms densely covered with small uniform tubercles (Figs 48-51). Ventral mantle with distinct keels (Figs 52-55). Head robust, neck usually only slightly narrower than head (but see Fig. 50; this may be an effect of long preservation in strong ethyl alcohol). Eyes dorso-lateral (Figs  48-51, 56).

Sepia (Digitosepia) faurei
Arms (Figs 57-59; Table 3) II-IV almost subequal in length; arms I longest. However, this was based upon eight individuals only, four of which were measured precisely (other specimens were hardened due to preservation in 96% ethyl alcohol). Arms relatively short, fleshy; keels especially prominent on ventral (IV) arms; on other arms keel prominence variable (Figs 57-59) and depends upon the state of preservation and possibly other factors. Protective membranes thick, fleshy, suckers bi-serial. Arms connected by membrane; it is the same depth and always much less than 1/4 of arm length between arms of I-III pairs, vestigial between arms III-IV, and there is no web between arms IV (Fig. 59). Suckers on arms relatively large; sucker rings with no teeth (Fig. 60). Diameter of suckers in females may change abruptly along III and IV arms (after 8th pair and again after 3rd-4th pair), but the character is variable. Tips of arms of I pair generally devoid of suckers (some may bear uni-serial odd suckers); length and structure of arm I tips quite variable; they may be of different length on each arm (range 7-13% of arm length) (Figs 61-63; Table 3). Left ventral arm hectocotylised (Fig. 64): eight pairs of medium-sized suckers in marginal rows. Suckers of similar size in dorsal and ventral row. Proximally 12 pairs of suckers, decreasing gradually in size towards tip. Low, rather inconspicuous fleshy transverse folds between marginal sucker pairs. Proximal part of hectocotylised arm noticeably widened. Right ventral arm not modified (Fig. 65), similar to right IV arm of the female (Fig.  67). Non-hectocotylised arms of males not modified (compare Figs 57-59). Tentacular stalk of moderate length (106-140% ML). Club small (12-14% ML), uniform with 10-11 rows, each with 3-4 suckers (Figs 68-71). Suckers minute (Fig. 60), chitinous rings mostly smooth but tiny indentation seen on some. Protective membranes narrow. Natatory membrane well developed, extends along tentacular stalk for about ½ of club length.
Upper beak : rostrum blunt, relatively short, not hooked, as long as wide, rostrum angle well defined; hood long, distal tip far from crest, jaw edge straight, jaw angle 90°; lateral wall strongly curved. Only rostrum and hood dark.
Lower beak (Figs 74-76): rostrum short, blunt, lacking distinct rostrum angle; hood low on crest, slightly curved, indented; crest slightly curved, not indented, not parallel to lower edge of lateral wall (proximally further apart than distally); lateral wall with curved and angled posterior margin, with no fold on upper part of lateral wall. Only rostrum and upper parts of shoulders dark. Radula homodont, with seven teeth per row (Fig.  60). Marginal plates not detected. Rhachidian teeth high, narrow, sharp, triangular, with small indentation at base. First and second laterals small, squat, symmetrical, with small indentation at base. Heels small, compact. Marginal teeth fairly uniform, long, blunt, moderately curved, not indented. Spermatophores (Fig. 60) seem to bear no species-specific characters, but they are illustrated for the record (for more detailed comparative research in the future).
Cuttlebone (Figs 82-83) broad, thick, heavily calcified, not transparent (except outer cone), with posterior part of inner cone as thin band, completely fused with outer cone, phragmocone and dorsal shield. Forked limbs absent, completely reduced. Outer cone broad, transparent, surrounds phragmocone and continues to anterior extremity. Septa strong, convex, closely spaced, they extend to anterior margin (as in most sepiids). Striae convex, strong. Dorsal shield simple, with no deposits. Posterior spine absent; inconspicuous knob on dorsal side of inner cone. If the cuttlebone is de-calcified during preservation (Figs 84-87 , 1920. However, in each case these tubercles are different; their detailed morphology and distribution should be examined comparatively, possibly on a worldwide scale. This, as well as the study of the cuttlebone, may prevent many mistakes and misunderstandings when undertaking future descriptions. All mentioned species differ pro-foundly from S. faurei in their size at maturity, their cuttlebones, and in the quadri-serial arrangements of suckers on arms (Roeleveld 1972). Roeleveld (1972: fig. 16a) well illustrated the most common structure of the tip of I pair of arms of S. faurei, but there is, as in other species of the subgenus Digitosepia, considerable intra-specific variation. Tentacular clubs are well compared by Roeleveld (1972 : table 6) among the three species, but not the cuttlebone. In particular, the S. faurei cuttlebone is not "completely chitinous" -on the contrary, it is strongly calcified (Figs 82-83). The cuttlebone of the holotype must have been completely de-calcified, possibly because it was stored in formalin from capture (1902) to the description (early 70s'). I have provided photographs of the holotype of Sepia (D.) faurei for comparisons and future reference (Appendix, Fig. A2). Distribution. Currently known from the small area of eastern Agulhas Bank (Fig. 1), with the depth range of 116-184 m. Therefore, it may be a species of the continental shelf. It is interesting to note that the ranges of S. faurei, S. barosei, S. roeleveldi and S. robsoni strongly overlap in one small area off the Tsitsikamma coast. Three of these uncommon species were taken by a single trawl!

DISCUSSION
With this detailed account of the morphology and systematic status of S. robsoni and S. faurei, the definition of the recently described subgenus Digitosepia (Lipiński 2020) is better founded and the specific characters illustrated. Particularly important was the preparation of a fairly intact and only slightly damaged cuttlebone of S. robsoni (Figs 42-43), the individual of which, after capture, was preserved in 70% ethyl alcohol only. The same applies to the specimens of S. faurei SAMC (stored only in ethyl alcohol; however, since these voucher specimens were intended for molecular analysis and genetic interpretation, the alcohol was 96% which made them hard and therefore difficult to handle and describe). The accumulated collection of cuttlebones of four species of Digitosepia, despite its serious shortcomings (on the whole, poor preservation of the material) allows their characteristics to be summarised as follows: Each species of Digitosepia has a different degree of calcification (understood simply as a build-up of cal-cium carbonate in a structure) -from extremely light (as in S. robsoni) to thick and heavy (as in S. faurei). This is a species-specific, environment-driven adaptation to extremely diverse environments in which these species live (denton & GiLpin-brown 1961). This interpretation, as well as the molecular analysis, led bonnaud et al. (2006: 148-149) to conclude that "the shell [cuttlebone -MRL] shape classically used as diagnostic of a lineage is not phylogenetically informative because of its phenotypic plasticity." Instead, they argued, that the "ventral part of the inner cone, seems robust in establishing the relationships of species in this group" [Sepia -MRL].
The postero-ventral (facing downwards when the animal swims) part of the inner cone has, on the other hand, fairly uniform characters in Digitosepia: it is fully integrated, narrow, flat (i.e. not protruding above the surface) and fused with the surrounding parts of the cuttlebone (Lipiński 2020: figs 33-34, 69-71;this contribution: Figs 42-47, 82-87). The The term "calcification" or "[degree] of calcification" is frequently used in descriptions of cuttlebones. However, various authors may use this term not exactly meaning the chemical process and its result, as most commonly defined accumulation of calcium salts in tissues, or deposition involving CaCO 3 in biological systems (see The Free Dictionary by Farlex [Free dictionary 2003] under "calcification" and weiner & addadi 2011). For example, when describing Sepia pulchra Roeleveld et Liltved, 1985, roeLeveLd & LiLtved (1985 stated that "The shell is not calcified and is broadly oval…", whereas their figs 10-11 show the cuttlebone relatively hard and rigid, full of calcium carbonate (I have examined the cuttlebone of the holotype and can confirm this). In this context, "not calcified" means that a proper, thick, structured phragmocone is not present. Although classifying various degrees of "calcification" of cuttlebones is outside the scope of this paper, there is certainly a need for such a study, following the structural and physiological background provided by denton & GiLpin-brown (1961) and sherrard Lipiński & LesLie (2018: 145) stated that "[small sepiids] are so different from one another that virtually the only trait that they share is their small size, and this trait alone cannot have any systematic significance." However, it has great systematic significance when combined with other characters. For example, individuals of S. joubini Massy, 1927 are also small but they differ from the whole Digitosepia group in the sucker arrangement on the arms. The small size at sexual maturity, bi-serial sucker arrangement on the arms, cuttlebone characters and possibly also modifications of IV arms in males, may be sufficient to grant a separate generic status to the small, near-endemic cuttlefishes of southern Africa. However, to confirm this, a full molecular evaluation will be necessary.